From c1fb339bbc4ef3c26c01a7528e8cbdbd6c5671d3 Mon Sep 17 00:00:00 2001
From: camperbot <dev@freecodecamp.org>
Date: Wed, 27 Oct 2021 15:10:57 +0000
Subject: [PATCH] chore(i18n,curriculum): update translations

---
 .../access-array-data-with-indexes.md         |  10 +-
 ...s-multi-dimensional-arrays-with-indexes.md |  24 ++--
 .../accessing-nested-arrays.md                |  11 +-
 .../accessing-nested-objects.md               |  11 +-
 ...object-properties-with-bracket-notation.md |  16 +--
 ...ing-object-properties-with-dot-notation.md |  21 ++--
 ...essing-object-properties-with-variables.md |  32 ++---
 ...d-new-properties-to-a-javascript-object.md |   6 +-
 .../add-two-numbers-with-javascript.md        |   6 +-
 ...g-a-default-option-in-switch-statements.md |   4 +-
 .../appending-variables-to-strings.md         |  13 +-
 .../build-javascript-objects.md               |  12 +-
 .../comparison-with-the-equality-operator.md  |   2 +-
 ...ound-assignment-with-augmented-addition.md |  20 +--
 ...ound-assignment-with-augmented-division.md |  18 +--
 ...ssignment-with-augmented-multiplication.md |  18 +--
 ...d-assignment-with-augmented-subtraction.md |  14 +--
 ...g-strings-with-the-plus-equals-operator.md |   8 +-
 .../constructing-strings-with-variables.md    |  12 +-
 .../basic-javascript/counting-cards.md        |   4 +-
 .../create-decimal-numbers-with-javascript.md |   5 +-
 .../decrement-a-number-with-javascript.md     |   8 +-
 ...ete-properties-from-a-javascript-object.md |   7 +-
 ...-one-decimal-by-another-with-javascript.md |   4 +-
 ...e-one-number-by-another-with-javascript.md |   6 +-
 .../escape-sequences-in-strings.md            |   4 +-
 .../escaping-literal-quotes-in-strings.md     |   6 +-
 .../finding-a-remainder-in-javascript.md      |   8 +-
 .../global-vs.-local-scope-in-functions.md    |  13 +-
 .../basic-javascript/golf-code.md             |   3 +-
 .../increment-a-number-with-javascript.md     |   8 +-
 .../introducing-else-statements.md            |   6 +-
 ...terate-through-an-array-with-a-for-loop.md |  14 ++-
 ...terate-with-javascript-do...while-loops.md |  23 ++--
 .../local-scope-and-functions.md              |   8 +-
 .../manipulate-arrays-with-push.md            |   9 +-
 .../manipulating-complex-objects.md           |   6 +-
 ...-identical-options-in-switch-statements.md |   6 +-
 .../multiply-two-decimals-with-javascript.md  |   4 +-
 .../multiply-two-numbers-with-javascript.md   |   6 +-
 .../nest-one-array-within-another-array.md    |   6 +-
 .../basic-javascript/profile-lookup.md        | 119 +++++++++---------
 .../quoting-strings-with-single-quotes.md     |  14 +--
 .../basic-javascript/record-collection.md     |   4 +-
 .../replace-loops-using-recursion.md          |   6 +-
 .../replacing-if-else-chains-with-switch.md   |   4 +-
 ...urn-a-value-from-a-function-with-return.md |   3 +-
 ...rom-many-options-with-switch-statements.md |   4 +-
 .../basic-javascript/shopping-list.md         |   4 +-
 .../basic-javascript/stand-in-line.md         |   6 +-
 ...in-one-variable-using-javascript-arrays.md |   6 +-
 ...one-number-from-another-with-javascript.md |   6 +-
 .../testing-objects-for-properties.md         |   3 +-
 .../understand-string-immutability.md         |   8 +-
 .../understanding-boolean-values.md           |   1 -
 ...ndefined-value-returned-from-a-function.md |   8 +-
 .../updating-object-properties.md             |   7 +-
 ...n-to-find-the-nth-character-in-a-string.md |  12 +-
 ...-recursion-to-create-a-range-of-numbers.md |   2 +-
 .../use-the-parseint-function-with-a-radix.md |   2 +-
 .../use-the-parseint-function.md              |   2 +-
 .../using-objects-for-lookups.md              |  11 +-
 .../basic-javascript/word-blanks.md           |  22 ++--
 ...f-an-array-using-concat-instead-of-push.md |  12 +-
 ...ramming-to-convert-strings-to-url-slugs.md |   1 -
 ...de-effects-using-functional-programming.md |   6 +-
 ...ray-into-a-string-using-the-join-method.md |   7 +-
 ...bine-two-arrays-using-the-concat-method.md |  12 +-
 .../implement-map-on-a-prototype.md           |  17 ++-
 ...lement-the-filter-method-on-a-prototype.md |  15 +--
 ...ion-to-currying-and-partial-application.md |   6 +-
 ...avoid-external-dependence-in-a-function.md |  14 +--
 ...-an-array-using-slice-instead-of-splice.md |  10 +-
 ...ray-without-changing-the-original-array.md |   9 +-
 ...part-of-an-array-using-the-slice-method.md |  14 +--
 ...ay-alphabetically-using-the-sort-method.md |   6 +-
 ...ng-into-an-array-using-the-split-method.md |  11 +-
 ...nd-the-hazards-of-using-imperative-code.md |  56 ++++-----
 ...ry-element-in-an-array-meets-a-criteria.md |   7 +-
 .../use-the-reduce-method-to-analyze-data.md  |  14 +--
 ...ny-elements-in-an-array-meet-a-criteria.md |   7 +-
 .../diff-two-arrays.md                        |   9 +-
 .../make-a-person.md                          |  10 +-
 .../map-the-debris.md                         |  12 +-
 .../smallest-common-multiple.md               |   1 -
 .../wherefore-art-thou.md                     |   6 +-
 .../caesars-cipher.md                         |   1 -
 .../cash-register.md                          |  97 +++++++-------
 .../palindrome-checker.md                     |   2 -
 .../access-array-data-with-indexes.md         |  10 +-
 ...s-multi-dimensional-arrays-with-indexes.md |  24 ++--
 .../accessing-nested-arrays.md                |  11 +-
 .../accessing-nested-objects.md               |  11 +-
 ...object-properties-with-bracket-notation.md |  16 +--
 ...ing-object-properties-with-dot-notation.md |  21 ++--
 ...essing-object-properties-with-variables.md |  32 ++---
 ...d-new-properties-to-a-javascript-object.md |   6 +-
 .../add-two-numbers-with-javascript.md        |   6 +-
 ...g-a-default-option-in-switch-statements.md |   4 +-
 .../appending-variables-to-strings.md         |  13 +-
 .../build-javascript-objects.md               |  12 +-
 .../comparison-with-the-equality-operator.md  |   2 +-
 ...ound-assignment-with-augmented-addition.md |  20 +--
 ...ound-assignment-with-augmented-division.md |  18 +--
 ...ssignment-with-augmented-multiplication.md |  18 +--
 ...d-assignment-with-augmented-subtraction.md |  14 +--
 ...g-strings-with-the-plus-equals-operator.md |   8 +-
 .../constructing-strings-with-variables.md    |  12 +-
 .../basic-javascript/counting-cards.md        |   4 +-
 .../create-decimal-numbers-with-javascript.md |   5 +-
 .../decrement-a-number-with-javascript.md     |   8 +-
 ...ete-properties-from-a-javascript-object.md |   7 +-
 ...-one-decimal-by-another-with-javascript.md |   4 +-
 ...e-one-number-by-another-with-javascript.md |   6 +-
 .../escape-sequences-in-strings.md            |   4 +-
 .../escaping-literal-quotes-in-strings.md     |   6 +-
 .../finding-a-remainder-in-javascript.md      |   8 +-
 .../global-vs.-local-scope-in-functions.md    |  13 +-
 .../basic-javascript/golf-code.md             |   3 +-
 .../increment-a-number-with-javascript.md     |   8 +-
 .../introducing-else-statements.md            |   6 +-
 ...terate-through-an-array-with-a-for-loop.md |  14 ++-
 ...terate-with-javascript-do...while-loops.md |  23 ++--
 .../local-scope-and-functions.md              |   8 +-
 .../manipulate-arrays-with-push.md            |   9 +-
 .../manipulating-complex-objects.md           |   6 +-
 ...-identical-options-in-switch-statements.md |   6 +-
 .../multiply-two-decimals-with-javascript.md  |   4 +-
 .../multiply-two-numbers-with-javascript.md   |   6 +-
 .../nest-one-array-within-another-array.md    |   6 +-
 .../basic-javascript/profile-lookup.md        | 119 +++++++++---------
 .../quoting-strings-with-single-quotes.md     |  14 +--
 .../basic-javascript/record-collection.md     |   4 +-
 .../replace-loops-using-recursion.md          |   6 +-
 .../replacing-if-else-chains-with-switch.md   |   4 +-
 ...urn-a-value-from-a-function-with-return.md |   3 +-
 ...rom-many-options-with-switch-statements.md |   4 +-
 .../basic-javascript/shopping-list.md         |   4 +-
 .../basic-javascript/stand-in-line.md         |   6 +-
 ...in-one-variable-using-javascript-arrays.md |   6 +-
 ...one-number-from-another-with-javascript.md |   6 +-
 .../testing-objects-for-properties.md         |   3 +-
 .../understand-string-immutability.md         |   8 +-
 .../understanding-boolean-values.md           |   1 -
 ...ndefined-value-returned-from-a-function.md |   8 +-
 .../updating-object-properties.md             |   7 +-
 ...n-to-find-the-nth-character-in-a-string.md |  12 +-
 ...-recursion-to-create-a-range-of-numbers.md |   2 +-
 .../use-the-parseint-function-with-a-radix.md |   2 +-
 .../use-the-parseint-function.md              |   2 +-
 .../using-objects-for-lookups.md              |  11 +-
 .../basic-javascript/word-blanks.md           |  22 ++--
 ...f-an-array-using-concat-instead-of-push.md |  12 +-
 ...ramming-to-convert-strings-to-url-slugs.md |   1 -
 ...de-effects-using-functional-programming.md |   6 +-
 ...ray-into-a-string-using-the-join-method.md |   7 +-
 ...bine-two-arrays-using-the-concat-method.md |  12 +-
 .../implement-map-on-a-prototype.md           |  17 ++-
 ...lement-the-filter-method-on-a-prototype.md |  15 +--
 ...ion-to-currying-and-partial-application.md |   6 +-
 ...avoid-external-dependence-in-a-function.md |  14 +--
 ...-an-array-using-slice-instead-of-splice.md |  10 +-
 ...ray-without-changing-the-original-array.md |   9 +-
 ...part-of-an-array-using-the-slice-method.md |  14 +--
 ...ay-alphabetically-using-the-sort-method.md |   6 +-
 ...ng-into-an-array-using-the-split-method.md |  11 +-
 ...nd-the-hazards-of-using-imperative-code.md |  56 ++++-----
 ...ry-element-in-an-array-meets-a-criteria.md |   7 +-
 .../use-the-reduce-method-to-analyze-data.md  |  14 +--
 ...ny-elements-in-an-array-meet-a-criteria.md |   7 +-
 .../diff-two-arrays.md                        |   9 +-
 .../make-a-person.md                          |  10 +-
 .../map-the-debris.md                         |  12 +-
 .../smallest-common-multiple.md               |   1 -
 .../wherefore-art-thou.md                     |   6 +-
 .../caesars-cipher.md                         |   1 -
 .../cash-register.md                          |  97 +++++++-------
 .../palindrome-checker.md                     |   2 -
 ...w-hierarchical-relationships-of-content.md |   6 +-
 .../access-array-data-with-indexes.md         |  10 +-
 ...s-multi-dimensional-arrays-with-indexes.md |  24 ++--
 .../accessing-nested-arrays.md                |  11 +-
 .../accessing-nested-objects.md               |  11 +-
 ...object-properties-with-bracket-notation.md |  16 +--
 ...ing-object-properties-with-dot-notation.md |  21 ++--
 ...essing-object-properties-with-variables.md |  32 ++---
 ...d-new-properties-to-a-javascript-object.md |   6 +-
 .../add-two-numbers-with-javascript.md        |   6 +-
 ...g-a-default-option-in-switch-statements.md |   4 +-
 .../appending-variables-to-strings.md         |  13 +-
 .../build-javascript-objects.md               |  12 +-
 .../comparison-with-the-equality-operator.md  |   2 +-
 ...ound-assignment-with-augmented-addition.md |  20 +--
 ...ound-assignment-with-augmented-division.md |  18 +--
 ...ssignment-with-augmented-multiplication.md |  18 +--
 ...d-assignment-with-augmented-subtraction.md |  14 +--
 ...g-strings-with-the-plus-equals-operator.md |   8 +-
 .../constructing-strings-with-variables.md    |  12 +-
 .../basic-javascript/counting-cards.md        |   4 +-
 .../create-decimal-numbers-with-javascript.md |   5 +-
 .../decrement-a-number-with-javascript.md     |   8 +-
 ...ete-properties-from-a-javascript-object.md |   7 +-
 ...-one-decimal-by-another-with-javascript.md |   4 +-
 ...e-one-number-by-another-with-javascript.md |   6 +-
 .../escape-sequences-in-strings.md            |   4 +-
 .../escaping-literal-quotes-in-strings.md     |   6 +-
 .../finding-a-remainder-in-javascript.md      |   8 +-
 .../global-vs.-local-scope-in-functions.md    |  13 +-
 .../basic-javascript/golf-code.md             |   3 +-
 .../increment-a-number-with-javascript.md     |   8 +-
 .../introducing-else-statements.md            |   6 +-
 ...terate-through-an-array-with-a-for-loop.md |  14 ++-
 ...terate-with-javascript-do...while-loops.md |  23 ++--
 .../local-scope-and-functions.md              |   8 +-
 .../manipulate-arrays-with-push.md            |   9 +-
 .../manipulating-complex-objects.md           |   6 +-
 ...-identical-options-in-switch-statements.md |   6 +-
 .../multiply-two-decimals-with-javascript.md  |   4 +-
 .../multiply-two-numbers-with-javascript.md   |   6 +-
 .../nest-one-array-within-another-array.md    |   6 +-
 .../basic-javascript/profile-lookup.md        | 119 +++++++++---------
 .../quoting-strings-with-single-quotes.md     |  14 +--
 .../basic-javascript/record-collection.md     |   4 +-
 .../replace-loops-using-recursion.md          |   6 +-
 .../replacing-if-else-chains-with-switch.md   |   4 +-
 ...urn-a-value-from-a-function-with-return.md |   3 +-
 ...rom-many-options-with-switch-statements.md |   4 +-
 .../basic-javascript/shopping-list.md         |   4 +-
 .../basic-javascript/stand-in-line.md         |   6 +-
 ...in-one-variable-using-javascript-arrays.md |   6 +-
 ...one-number-from-another-with-javascript.md |   6 +-
 .../testing-objects-for-properties.md         |   3 +-
 .../understand-string-immutability.md         |   8 +-
 .../understanding-boolean-values.md           |   1 -
 ...ndefined-value-returned-from-a-function.md |   8 +-
 .../updating-object-properties.md             |   7 +-
 ...n-to-find-the-nth-character-in-a-string.md |  12 +-
 ...-recursion-to-create-a-range-of-numbers.md |   2 +-
 .../use-the-parseint-function-with-a-radix.md |   2 +-
 .../use-the-parseint-function.md              |   2 +-
 .../using-objects-for-lookups.md              |  11 +-
 .../basic-javascript/word-blanks.md           |  22 ++--
 ...f-an-array-using-concat-instead-of-push.md |  12 +-
 ...ramming-to-convert-strings-to-url-slugs.md |   1 -
 ...de-effects-using-functional-programming.md |   6 +-
 ...ray-into-a-string-using-the-join-method.md |   7 +-
 ...bine-two-arrays-using-the-concat-method.md |  12 +-
 .../implement-map-on-a-prototype.md           |  17 ++-
 ...lement-the-filter-method-on-a-prototype.md |  15 +--
 ...ion-to-currying-and-partial-application.md |   6 +-
 ...avoid-external-dependence-in-a-function.md |  14 +--
 ...-an-array-using-slice-instead-of-splice.md |  10 +-
 ...ray-without-changing-the-original-array.md |   9 +-
 ...part-of-an-array-using-the-slice-method.md |  14 +--
 ...ay-alphabetically-using-the-sort-method.md |   6 +-
 ...ng-into-an-array-using-the-split-method.md |  11 +-
 ...nd-the-hazards-of-using-imperative-code.md |  56 ++++-----
 ...ry-element-in-an-array-meets-a-criteria.md |   7 +-
 .../use-the-reduce-method-to-analyze-data.md  |  14 +--
 ...ny-elements-in-an-array-meet-a-criteria.md |   7 +-
 .../diff-two-arrays.md                        |   9 +-
 .../make-a-person.md                          |  10 +-
 .../map-the-debris.md                         |  12 +-
 .../smallest-common-multiple.md               |   1 -
 .../wherefore-art-thou.md                     |   6 +-
 .../caesars-cipher.md                         |   1 -
 .../cash-register.md                          |  97 +++++++-------
 .../palindrome-checker.md                     |   2 -
 ...hain-middleware-to-create-a-time-server.md |  16 +--
 .../get-data-from-post-requests.md            |  22 ++--
 ...t-query-parameter-input-from-the-client.md |  12 +-
 ...t-route-parameter-input-from-the-client.md |  10 +-
 ...-a-root-level-request-logger-middleware.md |  14 +--
 .../serve-an-html-file.md                     |  10 +-
 .../serve-json-on-a-specific-route.md         |  10 +-
 .../serve-static-assets.md                    |  14 +--
 .../start-a-working-express-server.md         |  14 +--
 .../use-body-parser-to-parse-post-requests.md |  16 +--
 .../use-the-.env-file.md                      |  18 +--
 ...w-hierarchical-relationships-of-content.md |   6 +-
 ...ding-element-versus-a-paragraph-element.md |   7 +-
 ...l-balance-using-the-text-align-property.md |   2 +-
 .../use-the-s-tag-to-strikethrough-text.md    |   2 +-
 .../use-the-strong-tag-to-make-text-bold.md   |   2 +-
 ...radio-buttons-and-checkboxes-by-default.md |  12 ++
 .../access-array-data-with-indexes.md         |  10 +-
 ...s-multi-dimensional-arrays-with-indexes.md |  24 ++--
 .../accessing-nested-arrays.md                |  11 +-
 .../accessing-nested-objects.md               |  11 +-
 ...object-properties-with-bracket-notation.md |  16 +--
 ...ing-object-properties-with-dot-notation.md |  21 ++--
 ...essing-object-properties-with-variables.md |  32 ++---
 ...d-new-properties-to-a-javascript-object.md |   6 +-
 .../add-two-numbers-with-javascript.md        |   6 +-
 ...g-a-default-option-in-switch-statements.md |   4 +-
 .../appending-variables-to-strings.md         |  13 +-
 .../assignment-with-a-returned-value.md       |   3 +-
 .../build-javascript-objects.md               |  12 +-
 .../comparison-with-the-equality-operator.md  |   2 +-
 ...comparison-with-the-inequality-operator.md |   2 +-
 ...rison-with-the-strict-equality-operator.md |   2 +-
 ...ound-assignment-with-augmented-addition.md |  20 +--
 ...ound-assignment-with-augmented-division.md |  18 +--
 ...ssignment-with-augmented-multiplication.md |  18 +--
 ...d-assignment-with-augmented-subtraction.md |  14 +--
 ...oncatenating-strings-with-plus-operator.md |  10 +-
 ...g-strings-with-the-plus-equals-operator.md |   8 +-
 .../constructing-strings-with-variables.md    |  12 +-
 .../count-backwards-with-a-for-loop.md        |  16 +--
 .../basic-javascript/counting-cards.md        |   4 +-
 .../create-decimal-numbers-with-javascript.md |   5 +-
 ...ad-only-variable-with-the-const-keyword.md |  60 ++++-----
 .../declare-string-variables.md               |  10 +-
 .../decrement-a-number-with-javascript.md     |   8 +-
 ...ete-properties-from-a-javascript-object.md |   7 +-
 ...-one-decimal-by-another-with-javascript.md |   4 +-
 ...e-one-number-by-another-with-javascript.md |   6 +-
 .../escape-sequences-in-strings.md            |   4 +-
 .../escaping-literal-quotes-in-strings.md     |   6 +-
 ...rences-between-the-var-and-let-keywords.md |  55 +++-----
 .../find-the-length-of-a-string.md            |  15 ++-
 .../finding-a-remainder-in-javascript.md      |   8 +-
 .../global-scope-and-functions.md             |  12 +-
 .../global-vs.-local-scope-in-functions.md    |  13 +-
 .../basic-javascript/golf-code.md             |   3 +-
 .../increment-a-number-with-javascript.md     |   8 +-
 .../introducing-else-statements.md            |   6 +-
 .../iterate-odd-numbers-with-a-for-loop.md    |  16 +--
 ...terate-through-an-array-with-a-for-loop.md |  14 ++-
 ...terate-with-javascript-do...while-loops.md |  23 ++--
 .../iterate-with-javascript-for-loops.md      |  16 +--
 .../iterate-with-javascript-while-loops.md    |  18 +--
 .../local-scope-and-functions.md              |   8 +-
 .../manipulate-arrays-with-pop.md             |  16 +--
 .../manipulate-arrays-with-push.md            |   9 +-
 .../manipulate-arrays-with-shift.md           |  16 +--
 .../manipulate-arrays-with-unshift.md         |   9 +-
 .../manipulating-complex-objects.md           |   6 +-
 .../modify-array-data-with-indexes.md         |  11 +-
 ...-identical-options-in-switch-statements.md |   6 +-
 .../multiply-two-decimals-with-javascript.md  |   4 +-
 .../multiply-two-numbers-with-javascript.md   |   6 +-
 .../nest-one-array-within-another-array.md    |   6 +-
 .../basic-javascript/nesting-for-loops.md     |  27 ++--
 .../basic-javascript/profile-lookup.md        | 119 +++++++++---------
 .../quoting-strings-with-single-quotes.md     |  14 +--
 .../basic-javascript/record-collection.md     |   4 +-
 .../replace-loops-using-recursion.md          |   6 +-
 .../replacing-if-else-chains-with-switch.md   |   4 +-
 ...urn-a-value-from-a-function-with-return.md |   3 +-
 .../return-early-pattern-for-functions.md     |  14 +--
 ...returning-boolean-values-from-functions.md |   8 +-
 ...rom-many-options-with-switch-statements.md |   4 +-
 .../basic-javascript/shopping-list.md         |   4 +-
 .../basic-javascript/stand-in-line.md         |   6 +-
 ...in-one-variable-using-javascript-arrays.md |   6 +-
 ...one-number-from-another-with-javascript.md |   6 +-
 .../testing-objects-for-properties.md         |   3 +-
 .../understand-string-immutability.md         |   8 +-
 .../understanding-boolean-values.md           |   1 -
 ...ndefined-value-returned-from-a-function.md |   8 +-
 .../updating-object-properties.md             |   7 +-
 ...to-find-the-first-character-in-a-string.md |  14 +--
 ...-to-find-the-last-character-in-a-string.md |  14 +--
 ...n-to-find-the-nth-character-in-a-string.md |  12 +-
 ...d-the-nth-to-last-character-in-a-string.md |  14 +--
 ...se-conditional-logic-with-if-statements.md |   5 +-
 ...-recursion-to-create-a-range-of-numbers.md |   2 +-
 .../use-the-parseint-function-with-a-radix.md |   2 +-
 .../use-the-parseint-function.md              |   2 +-
 .../using-objects-for-lookups.md              |  11 +-
 .../basic-javascript/word-blanks.md           |  22 ++--
 ...pare-scopes-of-the-var-and-let-keywords.md |   4 +-
 .../mutate-an-array-declared-with-const.md    |   2 +
 ...f-an-array-using-concat-instead-of-push.md |  12 +-
 ...ramming-to-convert-strings-to-url-slugs.md |   1 -
 ...de-effects-using-functional-programming.md |   6 +-
 ...ray-into-a-string-using-the-join-method.md |   7 +-
 ...bine-two-arrays-using-the-concat-method.md |  12 +-
 .../implement-map-on-a-prototype.md           |  17 ++-
 ...lement-the-filter-method-on-a-prototype.md |  15 +--
 ...ion-to-currying-and-partial-application.md |   6 +-
 ...avoid-external-dependence-in-a-function.md |  14 +--
 ...actor-global-variables-out-of-functions.md |  24 ++--
 ...-an-array-using-slice-instead-of-splice.md |  10 +-
 ...ray-without-changing-the-original-array.md |   9 +-
 ...part-of-an-array-using-the-slice-method.md |  14 +--
 ...ay-alphabetically-using-the-sort-method.md |   6 +-
 ...ng-into-an-array-using-the-split-method.md |  11 +-
 ...nd-the-hazards-of-using-imperative-code.md |  56 ++++-----
 ...ry-element-in-an-array-meets-a-criteria.md |   7 +-
 ...er-method-to-extract-data-from-an-array.md |  13 +-
 ...ap-method-to-extract-data-from-an-array.md |  15 ++-
 .../use-the-reduce-method-to-analyze-data.md  |  14 +--
 ...ny-elements-in-an-array-meet-a-criteria.md |   7 +-
 .../diff-two-arrays.md                        |   9 +-
 .../make-a-person.md                          |  23 ++--
 .../map-the-debris.md                         |  12 +-
 .../smallest-common-multiple.md               |   1 -
 .../wherefore-art-thou.md                     |   6 +-
 .../caesars-cipher.md                         |   1 -
 .../cash-register.md                          |  97 +++++++-------
 .../palindrome-checker.md                     |   2 -
 .../build-a-markdown-previewer.md             |   2 +-
 .../react/access-props-using-this.props.md    |  87 ++++++-------
 .../react/create-a-controlled-form.md         |   2 +-
 .../react/create-a-react-component.md         |   2 +-
 ...state-in-the-user-interface-another-way.md |   2 +-
 .../render-state-in-the-user-interface.md     |   2 +-
 .../use-the-.env-file.md                      |   2 +
 .../stock-price-checker.md                    |   6 +-
 .../data-structures/breadth-first-search.md   |  28 ++---
 .../create-a-circular-queue.md                |  32 ++---
 .../data-structures/create-a-hash-table.md    |  32 ++---
 .../data-structures/create-a-queue-class.md   |   2 +-
 .../create-a-trie-search-tree.md              |  16 +--
 .../create-an-es6-javascript-map.md           |  14 ++-
 .../create-and-add-to-sets-in-es6.md          |  18 +--
 ...ete-a-leaf-node-in-a-binary-search-tree.md |  21 ++++
 ...-maximum-height-of-a-binary-search-tree.md |  28 ++---
 ...d-maximum-value-in-a-binary-search-tree.md |  16 +--
 .../implement-heap-sort-with-a-min-heap.md    |  18 +--
 .../insert-an-element-into-a-max-heap.md      |  70 ++++++-----
 .../data-structures/invert-a-binary-tree.md   |  12 +-
 .../remove-an-element-from-a-max-heap.md      |  54 ++++----
 ...ve-elements-from-a-linked-list-by-index.md |  28 ++---
 .../remove-elements-from-a-linked-list.md     |  24 ++--
 .../search-within-a-linked-list.md            |  28 ++---
 .../data-structures/typed-arrays.md           |  32 ++---
 .../use-.has-and-.size-on-an-es6-set.md       |  14 +--
 ...th-first-search-in-a-binary-search-tree.md |  22 ++--
 ...th-first-search-in-a-binary-search-tree.md |  26 ++--
 ...pread-and-notes-for-es5-set-integration.md |  14 +--
 .../work-with-nodes-in-a-linked-list.md       |  14 +--
 ...w-hierarchical-relationships-of-content.md |   6 +-
 ...ding-element-versus-a-paragraph-element.md |   7 +-
 ...l-balance-using-the-text-align-property.md |   2 +-
 .../use-the-s-tag-to-strikethrough-text.md    |   2 +-
 ...sections-of-a-page-with-anchor-elements.md |   2 +-
 .../access-array-data-with-indexes.md         |  10 +-
 ...s-multi-dimensional-arrays-with-indexes.md |  24 ++--
 .../accessing-nested-arrays.md                |  11 +-
 .../accessing-nested-objects.md               |  11 +-
 ...object-properties-with-bracket-notation.md |  16 +--
 ...ing-object-properties-with-dot-notation.md |  21 ++--
 ...essing-object-properties-with-variables.md |  32 ++---
 ...d-new-properties-to-a-javascript-object.md |   6 +-
 .../add-two-numbers-with-javascript.md        |   6 +-
 ...g-a-default-option-in-switch-statements.md |   4 +-
 .../appending-variables-to-strings.md         |  13 +-
 .../build-javascript-objects.md               |  12 +-
 .../comparison-with-the-equality-operator.md  |   2 +-
 ...ound-assignment-with-augmented-addition.md |  20 +--
 ...ound-assignment-with-augmented-division.md |  18 +--
 ...ssignment-with-augmented-multiplication.md |  18 +--
 ...d-assignment-with-augmented-subtraction.md |  14 +--
 ...g-strings-with-the-plus-equals-operator.md |   8 +-
 .../constructing-strings-with-variables.md    |  12 +-
 .../basic-javascript/counting-cards.md        |   4 +-
 .../create-decimal-numbers-with-javascript.md |   5 +-
 .../decrement-a-number-with-javascript.md     |   8 +-
 ...ete-properties-from-a-javascript-object.md |   7 +-
 ...-one-decimal-by-another-with-javascript.md |   4 +-
 ...e-one-number-by-another-with-javascript.md |   6 +-
 .../escape-sequences-in-strings.md            |   4 +-
 .../escaping-literal-quotes-in-strings.md     |   6 +-
 .../finding-a-remainder-in-javascript.md      |   8 +-
 .../global-vs.-local-scope-in-functions.md    |  13 +-
 .../basic-javascript/golf-code.md             |   3 +-
 .../increment-a-number-with-javascript.md     |   8 +-
 .../introducing-else-statements.md            |   6 +-
 ...terate-through-an-array-with-a-for-loop.md |  14 ++-
 ...terate-with-javascript-do...while-loops.md |  23 ++--
 .../local-scope-and-functions.md              |   8 +-
 .../manipulate-arrays-with-push.md            |   9 +-
 .../manipulating-complex-objects.md           |   6 +-
 ...-identical-options-in-switch-statements.md |   6 +-
 .../multiply-two-decimals-with-javascript.md  |   4 +-
 .../multiply-two-numbers-with-javascript.md   |   6 +-
 .../nest-one-array-within-another-array.md    |   6 +-
 .../basic-javascript/profile-lookup.md        | 119 +++++++++---------
 .../quoting-strings-with-single-quotes.md     |  14 +--
 .../basic-javascript/record-collection.md     |   4 +-
 .../replace-loops-using-recursion.md          |   6 +-
 .../replacing-if-else-chains-with-switch.md   |   4 +-
 ...urn-a-value-from-a-function-with-return.md |   3 +-
 ...rom-many-options-with-switch-statements.md |   4 +-
 .../basic-javascript/shopping-list.md         |   4 +-
 .../basic-javascript/stand-in-line.md         |   6 +-
 ...in-one-variable-using-javascript-arrays.md |   6 +-
 ...one-number-from-another-with-javascript.md |   6 +-
 .../testing-objects-for-properties.md         |   3 +-
 .../understand-string-immutability.md         |   8 +-
 .../understanding-boolean-values.md           |   1 -
 ...ndefined-value-returned-from-a-function.md |   8 +-
 .../updating-object-properties.md             |   7 +-
 ...n-to-find-the-nth-character-in-a-string.md |  12 +-
 ...-recursion-to-create-a-range-of-numbers.md |   2 +-
 .../use-the-parseint-function-with-a-radix.md |   2 +-
 .../use-the-parseint-function.md              |   2 +-
 .../using-objects-for-lookups.md              |  11 +-
 .../basic-javascript/word-blanks.md           |  22 ++--
 ...f-an-array-using-concat-instead-of-push.md |  12 +-
 ...ramming-to-convert-strings-to-url-slugs.md |   1 -
 ...de-effects-using-functional-programming.md |   6 +-
 ...ray-into-a-string-using-the-join-method.md |   7 +-
 ...bine-two-arrays-using-the-concat-method.md |  12 +-
 .../implement-map-on-a-prototype.md           |  17 ++-
 ...lement-the-filter-method-on-a-prototype.md |  15 +--
 ...ion-to-currying-and-partial-application.md |   6 +-
 ...avoid-external-dependence-in-a-function.md |  14 +--
 ...-an-array-using-slice-instead-of-splice.md |  10 +-
 ...ray-without-changing-the-original-array.md |   9 +-
 ...part-of-an-array-using-the-slice-method.md |  14 +--
 ...ay-alphabetically-using-the-sort-method.md |   6 +-
 ...ng-into-an-array-using-the-split-method.md |  11 +-
 ...nd-the-hazards-of-using-imperative-code.md |  56 ++++-----
 ...ry-element-in-an-array-meets-a-criteria.md |   7 +-
 .../use-the-reduce-method-to-analyze-data.md  |  14 +--
 ...ny-elements-in-an-array-meet-a-criteria.md |   7 +-
 .../diff-two-arrays.md                        |   9 +-
 .../make-a-person.md                          |  23 ++--
 .../map-the-debris.md                         |  12 +-
 .../smallest-common-multiple.md               |   1 -
 .../wherefore-art-thou.md                     |   6 +-
 .../caesars-cipher.md                         |   1 -
 .../cash-register.md                          |  97 +++++++-------
 .../palindrome-checker.md                     |   2 -
 .../build-a-markdown-previewer.md             |   2 +-
 .../react/access-props-using-this.props.md    |  87 ++++++-------
 .../react/compose-react-components.md         |   2 +-
 .../react/create-a-controlled-form.md         |   2 +-
 .../react/create-a-react-component.md         |   4 +-
 ...state-in-the-user-interface-another-way.md |   4 +-
 .../render-state-in-the-user-interface.md     |   4 +-
 .../react/set-state-with-this.setstate.md     |   4 +-
 .../use-the-.env-file.md                      |   2 +
 ...ete-a-leaf-node-in-a-binary-search-tree.md |  21 ++++
 .../problem-14-longest-collatz-sequence.md    |   2 +-
 539 files changed, 3319 insertions(+), 3352 deletions(-)

diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md
index 3bc677b78c6..f71b808172f 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md
@@ -18,9 +18,9 @@ dashedName: access-array-data-with-indexes
 **示例**
 
 ```js
-var array = [50,60,70];
+const array = [50, 60, 70];
 array[0];
-var data = array[1];
+const data = array[1];
 ```
 
 現在 `array[0]` 的值是 `50`， `data` 的值爲 `60`.
@@ -76,7 +76,7 @@ if(typeof myArray !== "undefined" && typeof myData !== "undefined"){(function(y,
 ## --seed-contents--
 
 ```js
-var myArray = [50,60,70];
+const myArray = [50, 60, 70];
 
 
 ```
@@ -84,6 +84,6 @@ var myArray = [50,60,70];
 # --solutions--
 
 ```js
-var myArray = [50,60,70];
-var myData = myArray[0];
+const myArray = [50, 60, 70];
+const myData = myArray[0];
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md
index f3a008e9b21..9378814a423 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md
@@ -14,12 +14,13 @@ dashedName: access-multi-dimensional-arrays-with-indexes
 **例如：**
 
 ```js
-var arr = [
-  [1,2,3],
-  [4,5,6],
-  [7,8,9],
-  [[10,11,12], 13, 14]
+const arr = [
+  [1, 2, 3],
+  [4, 5, 6],
+  [7, 8, 9],
+  [[10, 11, 12], 13, 14]
 ];
+
 arr[3];
 arr[3][0];
 arr[3][0][1];
@@ -58,14 +59,19 @@ if(typeof myArray !== "undefined"){(function(){return "myData: " + myData + " my
 ## --seed-contents--
 
 ```js
-var myArray = [[1,2,3], [4,5,6], [7,8,9], [[10,11,12], 13, 14]];
+const myArray = [
+  [1, 2, 3],
+  [4, 5, 6],
+  [7, 8, 9],
+  [[10, 11, 12], 13, 14],
+];
 
-var myData = myArray[0][0];
+const myData = myArray[0][0];
 ```
 
 # --solutions--
 
 ```js
-var myArray = [[1,2,3],[4,5,6], [7,8,9], [[10,11,12], 13, 14]];
-var myData = myArray[2][1];
+const myArray = [[1, 2, 3], [4, 5, 6], [7, 8, 9], [[10, 11, 12], 13, 14]];
+const myData = myArray[2][1];
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md
index 710204a32d0..f6d97b04c5f 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md
@@ -14,7 +14,7 @@ dashedName: accessing-nested-arrays
 下面是訪問嵌套數組的例子：
 
 ```js
-var ourPets = [
+const ourPets = [
   {
     animalType: "cat",
     names: [
@@ -32,6 +32,7 @@ var ourPets = [
     ]
   }
 ];
+
 ourPets[0].names[1];
 ourPets[1].names[0];
 ```
@@ -72,7 +73,7 @@ assert(/=\s*myPlants\[1\].list\[1\]/.test(code));
 ## --seed-contents--
 
 ```js
-var myPlants = [
+const myPlants = [
   {
     type: "flowers",
     list: [
@@ -91,13 +92,13 @@ var myPlants = [
   }
 ];
 
-var secondTree = "";
+const secondTree = "";
 ```
 
 # --solutions--
 
 ```js
-var myPlants = [
+const myPlants = [
   {
     type: "flowers",
     list: [
@@ -116,5 +117,5 @@ var myPlants = [
   }
 ];
 
-var secondTree = myPlants[1].list[1];
+const secondTree = myPlants[1].list[1];
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md
index 5f02f3269c0..c170f0179cc 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md
@@ -14,7 +14,7 @@ dashedName: accessing-nested-objects
 這是一個嵌套對象：
 
 ```js
-var ourStorage = {
+const ourStorage = {
   "desk": {
     "drawer": "stapler"
   },
@@ -26,6 +26,7 @@ var ourStorage = {
     "bottom drawer": "soda"
   }
 };
+
 ourStorage.cabinet["top drawer"].folder2;
 ourStorage.desk.drawer;
 ```
@@ -66,7 +67,7 @@ assert(/=\s*myStorage\.car\.inside\[\s*("|')glove box\1\s*\]/g.test(code));
 ## --seed-contents--
 
 ```js
-var myStorage = {
+const myStorage = {
   "car": {
     "inside": {
       "glove box": "maps",
@@ -78,13 +79,13 @@ var myStorage = {
   }
 };
 
-var gloveBoxContents = undefined;
+const gloveBoxContents = undefined;
 ```
 
 # --solutions--
 
 ```js
-var myStorage = {
+const myStorage = {
   "car":{
     "inside":{
       "glove box":"maps",
@@ -95,5 +96,5 @@ var myStorage = {
     }
   }
 };
-var gloveBoxContents = myStorage.car.inside["glove box"];
+const gloveBoxContents = myStorage.car.inside["glove box"];
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md
index 9e95bc1935c..fae451f97bc 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md
@@ -16,11 +16,12 @@ dashedName: accessing-object-properties-with-bracket-notation
 這是一個使用方括號表示法讀取對象屬性的例子：
 
 ```js
-var myObj = {
+const myObj = {
   "Space Name": "Kirk",
   "More Space": "Spock",
   "NoSpace": "USS Enterprise"
 };
+
 myObj["Space Name"];
 myObj['More Space'];
 myObj["NoSpace"];
@@ -78,26 +79,25 @@ assert(code.match(/testObj\s*?\[('|")[^'"]+\1\]/g).length > 1);
 
 ```js
 // Setup
-var testObj = {
+const testObj = {
   "an entree": "hamburger",
   "my side": "veggies",
   "the drink": "water"
 };
 
 // Only change code below this line
-
-var entreeValue = testObj;   // Change this line
-var drinkValue = testObj;    // Change this line
+const entreeValue = testObj;   // Change this line
+const drinkValue = testObj;    // Change this line
 ```
 
 # --solutions--
 
 ```js
-var testObj = {
+const testObj = {
   "an entree": "hamburger",
   "my side": "veggies",
   "the drink": "water"
 };
-var entreeValue = testObj["an entree"];
-var drinkValue = testObj['the drink'];
+const entreeValue = testObj["an entree"];
+const drinkValue = testObj['the drink'];
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md
index e7e0008a159..961e84417b9 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md
@@ -16,15 +16,17 @@ dashedName: accessing-object-properties-with-dot-notation
 這裏是一個用點符號（`.`）讀取對象屬性的示例：
 
 ```js
-var myObj = {
+const myObj = {
   prop1: "val1",
   prop2: "val2"
 };
-var prop1val = myObj.prop1;
-var prop2val = myObj.prop2;
+
+const prop1val = myObj.prop1;
+const prop2val = myObj.prop2;
 ```
 
 `prop1val` 的值將爲字符串 `val1`，並且`prop2val` 的值將爲字符串 `val2`。
+
 # --instructions--
 
 使用點號讀取 `testObj` 的屬性值。 將變量 `hatValue` 的值設置爲該對象的 `hat` 屬性的值，並將變量 `shirtValue` 的值設置爲該對象的 `shirt` 屬性的值。
@@ -73,27 +75,26 @@ assert(code.match(/testObj\.\w+/g).length > 1);
 
 ```js
 // Setup
-var testObj = {
+const testObj = {
   "hat": "ballcap",
   "shirt": "jersey",
   "shoes": "cleats"
 };
 
 // Only change code below this line
-
-var hatValue = testObj;      // Change this line
-var shirtValue = testObj;    // Change this line
+const hatValue = testObj;      // Change this line
+const shirtValue = testObj;    // Change this line
 ```
 
 # --solutions--
 
 ```js
-var testObj = {
+const testObj = {
   "hat": "ballcap",
   "shirt": "jersey",
   "shoes": "cleats"
 };
 
-var hatValue = testObj.hat;
-var shirtValue = testObj.shirt;
+const hatValue = testObj.hat;
+const shirtValue = testObj.shirt;
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md
index 4209de1bec7..fb59c32bfd8 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md
@@ -14,11 +14,14 @@ dashedName: accessing-object-properties-with-variables
 以下是一個使用變量來訪問屬性的例子：
 
 ```js
-var dogs = {
-  Fido: "Mutt",  Hunter: "Doberman",  Snoopie: "Beagle"
+const dogs = {
+  Fido: "Mutt",
+  Hunter: "Doberman",
+  Snoopie: "Beagle"
 };
-var myDog = "Hunter";
-var myBreed = dogs[myDog];
+
+const myDog = "Hunter";
+const myBreed = dogs[myDog];
 console.log(myBreed);
 ```
 
@@ -27,14 +30,16 @@ console.log(myBreed);
 使用這一概念的另一種情況是：屬性的名字是在程序運行期間動態收集得到的。如下所示：
 
 ```js
-var someObj = {
+const someObj = {
   propName: "John"
 };
+
 function propPrefix(str) {
-  var s = "prop";
+  const s = "prop";
   return s + str;
 }
-var someProp = propPrefix("Name");
+
+const someProp = propPrefix("Name");
 console.log(someObj[someProp]);
 ```
 
@@ -96,26 +101,25 @@ if(typeof player !== "undefined"){(function(v){return v;})(player);}
 
 ```js
 // Setup
-var testObj = {
+const testObj = {
   12: "Namath",
   16: "Montana",
   19: "Unitas"
 };
 
 // Only change code below this line
-
-var playerNumber;       // Change this line
-var player = testObj;   // Change this line
+const playerNumber = 42;  // Change this line
+const player = testObj;   // Change this line
 ```
 
 # --solutions--
 
 ```js
-var testObj = {
+const testObj = {
   12: "Namath",
   16: "Montana",
   19: "Unitas"
 };
-var playerNumber = 16;
-var player = testObj[playerNumber];
+const playerNumber = 16;
+const player = testObj[playerNumber];
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md
index 8019c13315b..b99d7e1d724 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md
@@ -28,7 +28,7 @@ ourDog["bark"] = "bow-wow";
 例如：
 
 ```js
-var ourDog = {
+const ourDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
@@ -67,7 +67,7 @@ assert(!/bark[^\n]:/.test(code));
 ## --seed-contents--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
@@ -80,7 +80,7 @@ var myDog = {
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md
index 233f3fd80cf..12a23a3a84e 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md
@@ -18,7 +18,7 @@ JavaScript 中，我們通過符號 `+` 來進行加法運算。
 **代碼示例:**
 
 ```js
-myVar = 5 + 10;
+const myVar = 5 + 10;
 ```
 
 現在，變量 `myVar` 的值爲 `15`。
@@ -52,11 +52,11 @@ assert(/\+/.test(code));
 ## --seed-contents--
 
 ```js
-var sum = 10 + 0;
+const sum = 10 + 0;
 ```
 
 # --solutions--
 
 ```js
-var sum = 10 + 10;
+const sum = 10 + 10;
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md
index 433b0df9a6d..b6f5dae2fe5 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md
@@ -92,7 +92,7 @@ assert(code.match(/break/g).length > 2);
 
 ```js
 function switchOfStuff(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
 
@@ -108,7 +108,7 @@ switchOfStuff(1);
 
 ```js
 function switchOfStuff(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case "a":
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md
index d23fb4ecf15..44569682541 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md
@@ -14,8 +14,8 @@ dashedName: appending-variables-to-strings
 示例：
 
 ```js
-var anAdjective = "awesome!";
-var ourStr = "freeCodeCamp is ";
+const anAdjective = "awesome!";
+let ourStr = "freeCodeCamp is ";
 ourStr += anAdjective;
 ```
 
@@ -64,15 +64,14 @@ assert(code.match(/myStr\s*\+=\s*someAdjective\s*/).length > 0);
 
 ```js
 // Change code below this line
-
-var someAdjective;
-var myStr = "Learning to code is ";
+const someAdjective = "";
+let myStr = "Learning to code is ";
 ```
 
 # --solutions--
 
 ```js
-var someAdjective = "neat";
-var myStr = "Learning to code is ";
+const someAdjective = "neat";
+let myStr = "Learning to code is ";
 myStr += someAdjective;
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md
index 408956d1ddb..6e1cb8200ad 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md
@@ -18,7 +18,7 @@ dashedName: build-javascript-objects
 這裏是一個貓對象的樣本：
 
 ```js
-var cat = {
+const cat = {
   "name": "Whiskers",
   "legs": 4,
   "tails": 1,
@@ -29,7 +29,7 @@ var cat = {
 在此示例中，所有屬性都存儲爲字符串，例如 `name`、`legs` 和 `tails`。 然而，你也可以使用數字作爲屬性。 你甚至可以省略單字字符串屬性中的引號，如下所示：
 
 ```js
-var anotherObject = {
+const anotherObject = {
   make: "Ford",
   5: "five",
   "model": "focus"
@@ -139,18 +139,18 @@ assert(
 ## --seed-contents--
 
 ```js
-var myDog = {
-// Only change code below this line
+const myDog = {
+  // Only change code below this line
 
 
-// Only change code above this line
+  // Only change code above this line
 };
 ```
 
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md
index 1a4b2e96a84..76ad74cb44d 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md
@@ -16,7 +16,7 @@ dashedName: comparison-with-the-equality-operator
 ```js
 function equalityTest(myVal) {
   if (myVal == 10) {
-     return "Equal";
+    return "Equal";
   }
   return "Not Equal";
 }
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md
index c571ebc638f..03ea0eed421 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md
@@ -20,7 +20,7 @@ myVar = myVar + 5;
 其中一種就是 `+=` 運算符。
 
 ```js
-var myVar = 1;
+let myVar = 1;
 myVar += 5;
 console.log(myVar);
 ```
@@ -61,9 +61,9 @@ assert(code.match(/\+=/g).length === 3);
 
 ```js
 assert(
-  /var a = 3;/.test(code) &&
-    /var b = 17;/.test(code) &&
-    /var c = 12;/.test(code)
+  /let a = 3;/.test(code) &&
+    /let b = 17;/.test(code) &&
+    /let c = 12;/.test(code)
 );
 ```
 
@@ -78,9 +78,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 3;
-var b = 17;
-var c = 12;
+let a = 3;
+let b = 17;
+let c = 12;
 
 // Only change code below this line
 a = a + 12;
@@ -91,9 +91,9 @@ c = c + 7;
 # --solutions--
 
 ```js
-var a = 3;
-var b = 17;
-var c = 12;
+let a = 3;
+let b = 17;
+let c = 12;
 
 a += 12;
 b += 9;
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md
index ce826e70845..8f72ef59378 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md
@@ -55,9 +55,9 @@ assert(code.match(/\/=/g).length === 3);
 
 ```js
 assert(
-  /var a = 48;/.test(code) &&
-    /var b = 108;/.test(code) &&
-    /var c = 33;/.test(code)
+  /let a = 48;/.test(code) &&
+    /let b = 108;/.test(code) &&
+    /let c = 33;/.test(code)
 );
 ```
 
@@ -72,9 +72,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 48;
-var b = 108;
-var c = 33;
+let a = 48;
+let b = 108;
+let c = 33;
 
 // Only change code below this line
 a = a / 12;
@@ -85,9 +85,9 @@ c = c / 11;
 # --solutions--
 
 ```js
-var a = 48;
-var b = 108;
-var c = 33;
+let a = 48;
+let b = 108;
+let c = 33;
 
 a /= 12;
 b /= 4;
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md
index d416d51a241..e7af1297212 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md
@@ -55,9 +55,9 @@ assert(code.match(/\*=/g).length === 3);
 
 ```js
 assert(
-  /var a = 5;/.test(code) &&
-    /var b = 12;/.test(code) &&
-    /var c = 4\.6;/.test(code)
+  /let a = 5;/.test(code) &&
+    /let b = 12;/.test(code) &&
+    /let c = 4\.6;/.test(code)
 );
 ```
 
@@ -72,9 +72,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 5;
-var b = 12;
-var c = 4.6;
+let a = 5;
+let b = 12;
+let c = 4.6;
 
 // Only change code below this line
 a = a * 5;
@@ -85,9 +85,9 @@ c = c * 10;
 # --solutions--
 
 ```js
-var a = 5;
-var b = 12;
-var c = 4.6;
+let a = 5;
+let b = 12;
+let c = 4.6;
 
 a *= 5;
 b *= 3;
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md
index 0f5b4749aea..1bf3a6d2d26 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md
@@ -55,7 +55,7 @@ assert(code.match(/-=/g).length === 3);
 
 ```js
 assert(
-  /var a = 11;/.test(code) && /var b = 9;/.test(code) && /var c = 3;/.test(code)
+  /let a = 11;/.test(code) && /let b = 9;/.test(code) && /let c = 3;/.test(code)
 );
 ```
 
@@ -70,9 +70,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 11;
-var b = 9;
-var c = 3;
+let a = 11;
+let b = 9;
+let c = 3;
 
 // Only change code below this line
 a = a - 6;
@@ -83,9 +83,9 @@ c = c - 1;
 # --solutions--
 
 ```js
-var a = 11;
-var b = 9;
-var c = 3;
+let a = 11;
+let b = 9;
+let c = 3;
 
 a -= 6;
 b -= 15;
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md
index f983cd7eb6f..6c93e3a8913 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md
@@ -16,7 +16,7 @@ dashedName: concatenating-strings-with-the-plus-equals-operator
 例如：
 
 ```js
-var ourStr = "I come first. ";
+let ourStr = "I come first. ";
 ourStr += "I come second.";
 ```
 
@@ -57,14 +57,12 @@ assert(code.match(/myStr\s*\+=\s*(["']).*\1/g));
 ## --seed-contents--
 
 ```js
-// Only change code below this line
-
-var myStr;
+let myStr;
 ```
 
 # --solutions--
 
 ```js
-var myStr = "This is the first sentence. ";
+let myStr = "This is the first sentence. ";
 myStr += "This is the second sentence.";
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md
index 496537114d6..61655e5ba6b 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md
@@ -14,8 +14,8 @@ dashedName: constructing-strings-with-variables
 例如：
 
 ```js
-var ourName = "freeCodeCamp";
-var ourStr = "Hello, our name is " + ourName + ", how are you?";
+const ourName = "freeCodeCamp";
+const ourStr = "Hello, our name is " + ourName + ", how are you?";
 ```
 
 `ourStr` 值爲 `Hello, our name is freeCodeCamp, how are you?`
@@ -63,13 +63,13 @@ assert(code.match(/["']\s*\+\s*myName\s*\+\s*["']/g).length > 0);
 
 ```js
 // Only change code below this line
-var myName;
-var myStr;
+const myName = "";
+const myStr = "";
 ```
 
 # --solutions--
 
 ```js
-var myName = "Bob";
-var myStr = "My name is " + myName + " and I am well!";
+const myName = "Bob";
+const myStr = "My name is " + myName + " and I am well!";
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md
index 5a75fe2de2c..fe9c860c585 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md
@@ -159,7 +159,7 @@ assert(
 ## --seed-contents--
 
 ```js
-var count = 0;
+let count = 0;
 
 function cc(card) {
   // Only change code below this line
@@ -175,7 +175,7 @@ cc(2); cc(3); cc(7); cc('K'); cc('A');
 # --solutions--
 
 ```js
-var count = 0;
+let count = 0;
 function cc(card) {
   switch(card) {
     case 2:
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md
index df7e68bc578..b29629c7882 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md
@@ -42,13 +42,14 @@ assert(myDecimal % 1 != 0);
 ## --seed-contents--
 
 ```js
-var ourDecimal = 5.7;
+const ourDecimal = 5.7;
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myDecimal = 9.9;
+const myDecimal = 9.9;
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md
index e573f61d882..936ad97e8e7 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md
@@ -39,7 +39,7 @@ assert(myVar === 10);
 
 ```js
 assert(
-  /var\s*myVar\s*=\s*11;\s*\/*.*\s*([-]{2}\s*myVar|myVar\s*[-]{2});/.test(code)
+  /let\s*myVar\s*=\s*11;\s*\/*.*\s*([-]{2}\s*myVar|myVar\s*[-]{2});/.test(code)
 );
 ```
 
@@ -52,7 +52,7 @@ assert(/[-]{2}\s*myVar|myVar\s*[-]{2}/.test(code));
 不應修改註釋上方的代碼。
 
 ```js
-assert(/var myVar = 11;/.test(code));
+assert(/let myVar = 11;/.test(code));
 ```
 
 # --seed--
@@ -66,7 +66,7 @@ assert(/var myVar = 11;/.test(code));
 ## --seed-contents--
 
 ```js
-var myVar = 11;
+let myVar = 11;
 
 // Only change code below this line
 myVar = myVar - 1;
@@ -75,6 +75,6 @@ myVar = myVar - 1;
 # --solutions--
 
 ```js
-var myVar = 11;
+let myVar = 11;
 myVar--;
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md
index 639da323151..358361c0dc4 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md
@@ -18,7 +18,7 @@ delete ourDog.bark;
 例如：
 
 ```js
-var ourDog = {
+const ourDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
@@ -70,7 +70,7 @@ assert(code.match(/"tails": 1/g).length > 0);
 
 ```js
 // Setup
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
@@ -79,12 +79,13 @@ var myDog = {
 };
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md
index 13331312e73..25b0e991643 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md
@@ -46,11 +46,11 @@ assert(code.match(/quotient/g).length === 1);
 ## --seed-contents--
 
 ```js
-var quotient = 0.0 / 2.0; // Change this line
+const quotient = 0.0 / 2.0; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var quotient = 4.4 / 2.0;
+const quotient = 4.4 / 2.0;
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md
index 4852f262ed2..8b0e9eef966 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md
@@ -16,7 +16,7 @@ JavaScript 中使用 `/` 符號做除法運算。
 **示例**
 
 ```js
-myVar = 16 / 2;
+const myVar = 16 / 2;
 ```
 
 現在，變量 `myVar` 的值爲 `8`。
@@ -49,11 +49,11 @@ assert(/\d+\s*\/\s*\d+/.test(code));
 ## --seed-contents--
 
 ```js
-var quotient = 66 / 0;
+const quotient = 66 / 0;
 ```
 
 # --solutions--
 
 ```js
-var quotient = 66 / 33;
+const quotient = 66 / 33;
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md
index f96a754cb25..bccac3a3929 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md
@@ -89,11 +89,11 @@ console.log('myStr:\n' + myStr);}})();
 ## --seed-contents--
 
 ```js
-var myStr; // Change this line
+const myStr = ""; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var myStr = "FirstLine\n\t\\SecondLine\nThirdLine";
+const myStr = "FirstLine\n\t\\SecondLine\nThirdLine";
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md
index 45942bb07b2..54e3c539f7d 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md
@@ -14,7 +14,7 @@ dashedName: escaping-literal-quotes-in-strings
 在 JavaScript 中，可以通過在引號前面使用<dfn>反斜槓</dfn>（`\`）來<dfn>轉義</dfn>引號。
 
 ```js
-var sampleStr = "Alan said, \"Peter is learning JavaScript\".";
+const sampleStr = "Alan said, \"Peter is learning JavaScript\".";
 ```
 
 有了轉義符號，JavaScript 就知道這個單引號或雙引號並不是字符串的結尾，而是字符串內的字符。 所以，上面的字符串打印到控制檯的結果爲：
@@ -62,11 +62,11 @@ assert(/I am a "double quoted" string inside "double quotes(\."|"\.)$/.test(mySt
 ## --seed-contents--
 
 ```js
-var myStr = ""; // Change this line
+const myStr = ""; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var myStr = "I am a \"double quoted\" string inside \"double quotes\".";
+const myStr = "I am a \"double quoted\" string inside \"double quotes\".";
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md
index b00b736b669..46232cd76d9 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md
@@ -31,7 +31,7 @@ dashedName: finding-a-remainder-in-javascript
 變量 `remainder` 應該被初始化。
 
 ```js
-assert(/var\s+?remainder/.test(code));
+assert(/(const|let|var)\s+?remainder/.test(code));
 ```
 
 `remainder` 的值應該等於 `2`。
@@ -57,13 +57,11 @@ assert(/\s+?remainder\s*?=\s*?.*%.*;?/.test(code));
 ## --seed-contents--
 
 ```js
-// Only change code below this line
-
-var remainder;
+const remainder = 0;
 ```
 
 # --solutions--
 
 ```js
-var remainder =  11 % 3;
+const remainder = 11 % 3;
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md
index 9499047290a..70d72bd9777 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md
@@ -14,9 +14,10 @@ dashedName: global-vs--local-scope-in-functions
 下面爲例：
 
 ```js
-var someVar = "Hat";
+const someVar = "Hat";
+
 function myFun() {
-  var someVar = "Head";
+  const someVar = "Head";
   return someVar;
 }
 ```
@@ -53,13 +54,11 @@ assert(/return outerWear/.test(code));
 
 ```js
 // Setup
-var outerWear = "T-Shirt";
+const outerWear = "T-Shirt";
 
 function myOutfit() {
   // Only change code below this line
 
-
-
   // Only change code above this line
   return outerWear;
 }
@@ -70,9 +69,9 @@ myOutfit();
 # --solutions--
 
 ```js
-var outerWear = "T-Shirt";
+const outerWear = "T-Shirt";
 function myOutfit() {
-  var outerWear = "sweater";
+  const outerWear = "sweater";
   return outerWear;
 }
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md
index 8dade6734c6..da6e34d887c 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md
@@ -90,7 +90,8 @@ assert(golfScore(5, 9) === 'Go Home!');
 ## --seed-contents--
 
 ```js
-var names = ["Hole-in-one!", "Eagle", "Birdie", "Par", "Bogey", "Double Bogey", "Go Home!"];
+const names = ["Hole-in-one!", "Eagle", "Birdie", "Par", "Bogey", "Double Bogey", "Go Home!"];
+
 function golfScore(par, strokes) {
   // Only change code below this line
 
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md
index 777a1bc649b..ca78824c500 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md
@@ -39,7 +39,7 @@ assert(myVar === 88);
 
 ```js
 assert(
-  /var\s*myVar\s*=\s*87;\s*\/*.*\s*([+]{2}\s*myVar|myVar\s*[+]{2});/.test(code)
+  /let\s*myVar\s*=\s*87;\s*\/*.*\s*([+]{2}\s*myVar|myVar\s*[+]{2});/.test(code)
 );
 ```
 
@@ -52,7 +52,7 @@ assert(/[+]{2}\s*myVar|myVar\s*[+]{2}/.test(code));
 不應該修改註釋上面的代碼。
 
 ```js
-assert(/var myVar = 87;/.test(code));
+assert(/let myVar = 87;/.test(code));
 ```
 
 # --seed--
@@ -66,7 +66,7 @@ assert(/var myVar = 87;/.test(code));
 ## --seed-contents--
 
 ```js
-var myVar = 87;
+let myVar = 87;
 
 // Only change code below this line
 myVar = myVar + 1;
@@ -75,6 +75,6 @@ myVar = myVar + 1;
 # --solutions--
 
 ```js
-var myVar = 87;
+let myVar = 87;
 myVar++;
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md
index 9e3ff3c710b..37f119c5936 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md
@@ -64,7 +64,7 @@ assert(testElse(10) === 'Bigger than 5');
 不要修改相應註釋的上面或下面的代碼。
 
 ```js
-assert(/var result = "";/.test(code) && /return result;/.test(code));
+assert(/let result = "";/.test(code) && /return result;/.test(code));
 ```
 
 # --seed--
@@ -73,7 +73,7 @@ assert(/var result = "";/.test(code) && /return result;/.test(code));
 
 ```js
 function testElse(val) {
-  var result = "";
+  let result = "";
   // Only change code below this line
 
   if (val > 5) {
@@ -95,7 +95,7 @@ testElse(4);
 
 ```js
 function testElse(val) {
-  var result = "";
+  let result = "";
   if(val > 5) {
     result = "Bigger than 5";
   } else {
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md
index 677aea61e9b..95eebdca777 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md
@@ -12,8 +12,9 @@ dashedName: iterate-through-an-array-with-a-for-loop
 JavaScript 中的一個常見任務是遍歷數組的內容。 一種方法是使用 `for` 循環。 下面的代碼將輸出數組 `arr` 的每個元素到控制檯：
 
 ```js
-var arr = [10, 9, 8, 7, 6];
-for (var i = 0; i < arr.length; i++) {
+const arr = [10, 9, 8, 7, 6];
+
+for (let i = 0; i < arr.length; i++) {
    console.log(arr[i]);
 }
 ```
@@ -62,18 +63,19 @@ assert(!__helpers.removeWhiteSpace(code).match(/total[=+-]0*[1-9]+/gm));
 
 ```js
 // Setup
-var myArr = [ 2, 3, 4, 5, 6];
+const myArr = [2, 3, 4, 5, 6];
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myArr = [ 2, 3, 4, 5, 6];
-var total = 0;
+const myArr = [2, 3, 4, 5, 6];
+let total = 0;
 
-for (var i = 0; i < myArr.length; i++) {
+for (let i = 0; i < myArr.length; i++) {
   total += myArr[i];
 }
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md
index b64f2bac08a..9eb71f2857f 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md
@@ -12,8 +12,9 @@ dashedName: iterate-with-javascript-do---while-loops
 下一種循環叫作 `do...while` 循環。 它被稱爲 `do...while` 循環，是因爲不論什麼情況，它都會首先 `do`（運行）循環裏的第一部分代碼，然後 `while`（當）規定的條件被評估爲 `true`（真）的時候，它會繼續運行循環。
 
 ```js
-var ourArray = [];
-var i = 0;
+const ourArray = [];
+let i = 0;
+
 do {
   ourArray.push(i);
   i++;
@@ -23,8 +24,9 @@ do {
 上面的示例行爲類似於其他類型的循環，由此產生的數組將看起來像 `[0, 1, 2, 3, 4]`。 然而，`do...while` 不同於其他循環的地方，是第一次循環檢查失敗時的行爲。 讓我們看看代碼中的區別：這裏是一個常規的 `while` 循環，只要 `i < 5`，就會在循環中運行代碼：
 
 ```js
-var ourArray = []; 
-var i = 5;
+const ourArray = []; 
+let i = 5;
+
 while (i < 5) {
   ourArray.push(i);
   i++;
@@ -34,8 +36,9 @@ while (i < 5) {
 這個例子中，定義了一個空數組 `ourArray` 以及一個值爲 5 的 `i` 。 當執行 `while` 循環時，因爲 `i` 不小於 5，所以循環條件爲 `false`，循環內的代碼將不會執行。 `ourArray` 最終沒有添加任何內容，因此示例中的所有代碼執行完時，ourArray 仍然是`[]`。 現在，看一下 `do...while` 循環。
 
 ```js
-var ourArray = []; 
-var i = 5;
+const ourArray = []; 
+let i = 5;
+
 do {
   ourArray.push(i);
   i++;
@@ -80,8 +83,8 @@ if(typeof myArray !== "undefined"){(function(){return myArray;})();}
 
 ```js
 // Setup
-var myArray = [];
-var i = 10;
+const myArray = [];
+let i = 10;
 
 // Only change code below this line
 while (i < 5) {
@@ -93,8 +96,8 @@ while (i < 5) {
 # --solutions--
 
 ```js
-var myArray = [];
-var i = 10;
+const myArray = [];
+let i = 10;
 do {
   myArray.push(i);
   i++;
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md
index a288458974d..a3af68c7678 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md
@@ -15,9 +15,10 @@ dashedName: local-scope-and-functions
 
 ```js
 function myTest() {
-  var loc = "foo";
+  const loc = "foo";
   console.log(loc);
 }
+
 myTest();
 console.log(loc);
 ```
@@ -38,6 +39,7 @@ console.log(loc);
 function declared() {
   myVar;
 }
+
 assert.throws(declared, ReferenceError);
 ```
 
@@ -57,7 +59,6 @@ assert(
 
 ```js
 function myLocalScope() {
-
   // Only change code below this line
 
   console.log('inside myLocalScope', myVar);
@@ -73,9 +74,8 @@ console.log('outside myLocalScope', myVar);
 
 ```js
 function myLocalScope() {
-
   // Only change code below this line
-  var myVar;
+  let myVar;
   console.log('inside myLocalScope', myVar);
 }
 myLocalScope();
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md
index 777ce483d85..b8eef3075ff 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md
@@ -16,10 +16,10 @@ dashedName: manipulate-arrays-with-push
 示例：
 
 ```js
-var arr1 = [1,2,3];
+const arr1 = [1, 2, 3];
 arr1.push(4);
 
-var arr2 = ["Stimpson", "J", "cat"];
+const arr2 = ["Stimpson", "J", "cat"];
 arr2.push(["happy", "joy"]);
 ```
 
@@ -64,14 +64,15 @@ assert(
 
 ```js
 // Setup
-var myArray = [["John", 23], ["cat", 2]];
+const myArray = [["John", 23], ["cat", 2]];
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myArray = [["John", 23], ["cat", 2]];
+const myArray = [["John", 23], ["cat", 2]];
 myArray.push(["dog",3]);
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md
index a011884850f..f303012dad8 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md
@@ -14,7 +14,7 @@ dashedName: manipulating-complex-objects
 這是一個複雜數據結構的示例：
 
 ```js
-var ourMusic = [
+const ourMusic = [
   {
     "artist": "Daft Punk",
     "title": "Homework",
@@ -135,7 +135,7 @@ myMusic.forEach(object => {
 ## --seed-contents--
 
 ```js
-var myMusic = [
+const myMusic = [
   {
     "artist": "Billy Joel",
     "title": "Piano Man",
@@ -153,7 +153,7 @@ var myMusic = [
 # --solutions--
 
 ```js
-var myMusic = [
+const myMusic = [
   {
     "artist": "Billy Joel",
     "title": "Piano Man",
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md
index fbe5f63ad56..b94f5c079de 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md
@@ -12,7 +12,7 @@ dashedName: multiple-identical-options-in-switch-statements
 如果你忘了給 `switch` 的每一條 `case` 添加 `break`，那麼後續的 `case` 會一直執行，直到遇見 `break` 爲止。 如果你想爲 `switch` 中的多個不同的輸入設置相同的結果，可以這樣寫：
 
 ```js
-var result = "";
+let result = "";
 switch(val) {
   case 1:
   case 2:
@@ -109,7 +109,7 @@ assert(code.match(/case/g).length === 9);
 
 ```js
 function sequentialSizes(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
 
@@ -125,7 +125,7 @@ sequentialSizes(1);
 
 ```js
 function sequentialSizes(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case 1:
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md
index c3cfa697263..b3696fed5ce 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md
@@ -42,11 +42,11 @@ assert(/\*/.test(code));
 ## --seed-contents--
 
 ```js
-var product = 2.0 * 0.0;
+const product = 2.0 * 0.0;
 ```
 
 # --solutions--
 
 ```js
-var product = 2.0 * 2.5;
+const product = 2.0 * 2.5;
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md
index b94896fa86a..68345e124f2 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md
@@ -16,7 +16,7 @@ JavaScript 使用 `*` 符號表示兩數相乘。
 **示例**
 
 ```js
-myVar = 13 * 13;
+const myVar = 13 * 13;
 ```
 
 現在，變量 `myVar` 的值爲 `169`。
@@ -50,11 +50,11 @@ assert(/\*/.test(code));
 ## --seed-contents--
 
 ```js
-var product = 8 * 0;
+const product = 8 * 0;
 ```
 
 # --solutions--
 
 ```js
-var product = 8 * 10;
+const product = 8 * 10;
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md
index 1d1a824772e..80950a3b85a 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md
@@ -12,7 +12,7 @@ dashedName: nest-one-array-within-another-array
 您也可以在其他數組中嵌套數組，如：
 
 ```js
-[["Bulls", 23], ["White Sox", 45]]
+const teams = [["Bulls", 23], ["White Sox", 45]];
 ```
 
 這也叫做多維數組（<dfn>multi-dimensional array</dfn>）。
@@ -41,11 +41,11 @@ if(typeof myArray !== "undefined"){(function(){return myArray;})();}
 
 ```js
 // Only change code below this line
-var myArray = [];
+const myArray = [];
 ```
 
 # --solutions--
 
 ```js
-var myArray = [[1,2,3]];
+const myArray = [[1, 2, 3]];
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md
index 69aef8d3888..0d35c8f304d 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md
@@ -68,34 +68,33 @@ assert(lookUpProfile('Akira', 'address') === 'No such property');
 
 ```js
 // Setup
-var contacts = [
-    {
-        "firstName": "Akira",
-        "lastName": "Laine",
-        "number": "0543236543",
-        "likes": ["Pizza", "Coding", "Brownie Points"]
-    },
-    {
-        "firstName": "Harry",
-        "lastName": "Potter",
-        "number": "0994372684",
-        "likes": ["Hogwarts", "Magic", "Hagrid"]
-    },
-    {
-        "firstName": "Sherlock",
-        "lastName": "Holmes",
-        "number": "0487345643",
-        "likes": ["Intriguing Cases", "Violin"]
-    },
-    {
-        "firstName": "Kristian",
-        "lastName": "Vos",
-        "number": "unknown",
-        "likes": ["JavaScript", "Gaming", "Foxes"]
-    }
+const contacts = [
+  {
+    firstName: "Akira",
+    lastName: "Laine",
+    number: "0543236543",
+    likes: ["Pizza", "Coding", "Brownie Points"],
+  },
+  {
+    firstName: "Harry",
+    lastName: "Potter",
+    number: "0994372684",
+    likes: ["Hogwarts", "Magic", "Hagrid"],
+  },
+  {
+    firstName: "Sherlock",
+    lastName: "Holmes",
+    number: "0487345643",
+    likes: ["Intriguing Cases", "Violin"],
+  },
+  {
+    firstName: "Kristian",
+    lastName: "Vos",
+    number: "unknown",
+    likes: ["JavaScript", "Gaming", "Foxes"],
+  },
 ];
 
-
 function lookUpProfile(name, prop) {
   // Only change code below this line
 
@@ -108,44 +107,38 @@ lookUpProfile("Akira", "likes");
 # --solutions--
 
 ```js
-var contacts = [
-    {
-        "firstName": "Akira",
-        "lastName": "Laine",
-        "number": "0543236543",
-        "likes": ["Pizza", "Coding", "Brownie Points"]
-    },
-    {
-        "firstName": "Harry",
-        "lastName": "Potter",
-        "number": "0994372684",
-        "likes": ["Hogwarts", "Magic", "Hagrid"]
-    },
-    {
-        "firstName": "Sherlock",
-        "lastName": "Holmes",
-        "number": "0487345643",
-        "likes": ["Intriguing Cases", "Violin"]
-    },
-    {
-        "firstName": "Kristian",
-        "lastName": "Vos",
-        "number": "unknown",
-        "likes": ["JavaScript", "Gaming", "Foxes"]
-    },
+const contacts = [
+  {
+    firstName: "Akira",
+    lastName: "Laine",
+    number: "0543236543",
+    likes: ["Pizza", "Coding", "Brownie Points"],
+  },
+  {
+    firstName: "Harry",
+    lastName: "Potter",
+    number: "0994372684",
+    likes: ["Hogwarts", "Magic", "Hagrid"],
+  },
+  {
+    firstName: "Sherlock",
+    lastName: "Holmes",
+    number: "0487345643",
+    likes: ["Intriguing Cases", "Violin"],
+  },
+  {
+    firstName: "Kristian",
+    lastName: "Vos",
+    number: "unknown",
+    likes: ["JavaScript", "Gaming", "Foxes"],
+  },
 ];
-
-
-//Write your function in between these comments
-function lookUpProfile(name, prop){
-    for(var i in contacts){
-      if(contacts[i].firstName === name) {
-        return contacts[i][prop] || "No such property";
-      }
+function lookUpProfile(name, prop) {
+  for (let i in contacts) {
+    if (contacts[i].firstName === name) {
+      return contacts[i][prop] || "No such property";
     }
-   return "No such contact";
+  }
+  return "No such contact";
 }
-//Write your function in between these comments
-
-lookUpProfile("Akira", "likes");
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md
index 3474275e9c6..d80d8fb1a58 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md
@@ -12,21 +12,21 @@ dashedName: quoting-strings-with-single-quotes
 JavaScript 中的<dfn>字符串</dfn>可以使用開始和結束都是同類型的單引號或雙引號表示。 與其他一些編程語言不同的是，單引號和雙引號的功能在 JavaScript 中是相同的。
 
 ```js
-doubleQuoteStr = "This is a string"; 
-singleQuoteStr = 'This is also a string';
+const doubleQuoteStr = "This is a string"; 
+const singleQuoteStr = 'This is also a string';
 ```
 
 當你需要在一個字符串中使用多個引號的時候，你可以使用單引號包裹雙引號或者相反。 常見的場景比如在字符串中包含對話的句子需要用引號包裹。 另外比如在一個包含有 `<a>` 標籤的字符串中，標籤的屬性值需要用引號包裹。
 
 ```js
-conversation = 'Finn exclaims to Jake, "Algebraic!"';
+const conversation = 'Finn exclaims to Jake, "Algebraic!"';
 ```
 
 然而，如果你需要在其中使用外面的引號，這就成爲一個問題。 記住，一個字符串在開頭和結尾處有相同的引號。 要知道，字符串在開頭和結尾都有相同的引號，如果在中間使用了相同的引號，字符串會提前中止並拋出錯誤。
 
 ```js
-goodStr = 'Jake asks Finn, "Hey, let\'s go on an adventure?"'; 
-badStr = 'Finn responds, "Let's go!"';
+const goodStr = 'Jake asks Finn, "Hey, let\'s go on an adventure?"'; 
+const badStr = 'Finn responds, "Let's go!"';
 ```
 
 在這裏 `badStr` 會產生一個錯誤。
@@ -71,11 +71,11 @@ assert(code.match(/"/g).length === 4 && code.match(/'/g).length === 2);
 ## --seed-contents--
 
 ```js
-var myStr = "<a href=\"http://www.example.com\" target=\"_blank\">Link</a>";
+const myStr = "<a href=\"http://www.example.com\" target=\"_blank\">Link</a>";
 ```
 
 # --solutions--
 
 ```js
-var myStr = '<a href="http://www.example.com" target="_blank">Link</a>';
+const myStr = '<a href="http://www.example.com" target="_blank">Link</a>';
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md
index e361219904c..2c700ef03f1 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md
@@ -115,7 +115,7 @@ const _recordCollection = {
 
 ```js
 // Setup
-var recordCollection = {
+const recordCollection = {
   2548: {
     albumTitle: 'Slippery When Wet',
     artist: 'Bon Jovi',
@@ -146,7 +146,7 @@ updateRecords(recordCollection, 5439, 'artist', 'ABBA');
 # --solutions--
 
 ```js
-var recordCollection = {
+const recordCollection = {
   2548: {
     albumTitle: 'Slippery When Wet',
     artist: 'Bon Jovi',
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md
index b0f92e916b7..6a73a9abbb6 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md
@@ -14,9 +14,9 @@ dashedName: replace-loops-using-recursion
 
 ```js
   function multiply(arr, n) {
-    var product = 1;
-    for (var i = 0; i < n; i++) {
-        product *= arr[i];
+    let product = 1;
+    for (let i = 0; i < n; i++) {
+      product *= arr[i];
     }
     return product;
   }
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md
index 3ef0e72f7e4..8ebaddff5bb 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md
@@ -108,7 +108,7 @@ assert(chainToSwitch(156) === '');
 
 ```js
 function chainToSwitch(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
   if (val === "bob") {
@@ -134,7 +134,7 @@ chainToSwitch(7);
 
 ```js
 function chainToSwitch(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case "bob":
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md
index 4416139da43..f7948934189 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md
@@ -17,7 +17,8 @@ dashedName: return-a-value-from-a-function-with-return
 function plusThree(num) {
   return num + 3;
 }
-var answer = plusThree(5);
+
+const answer = plusThree(5);
 ```
 
 `answer` 的值爲 `8`。
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md
index fe19b809337..e1058894151 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md
@@ -78,7 +78,7 @@ assert(code.match(/break/g).length > 2);
 
 ```js
 function caseInSwitch(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
 
@@ -94,7 +94,7 @@ caseInSwitch(1);
 
 ```js
 function caseInSwitch(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case 1:
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md
index 3712d37fd39..821da4e8ed0 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md
@@ -81,13 +81,13 @@ var hasNumber = false;
 ## --seed-contents--
 
 ```js
-var myList = [];
+const myList = [];
 ```
 
 # --solutions--
 
 ```js
-var myList = [
+const myList = [
   ["Candy", 10],
   ["Potatoes", 12],
   ["Eggs", 12],
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md
index 5c4ea46a83b..25a8a539ef0 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md
@@ -93,12 +93,10 @@ function nextInLine(arr, item) {
 
   return item;
   // Only change code above this line
-
-
 }
 
 // Setup
-var testArr = [1,2,3,4,5];
+const testArr = [1, 2, 3, 4, 5];
 
 // Display code
 console.log("Before: " + JSON.stringify(testArr));
@@ -109,7 +107,7 @@ console.log("After: " + JSON.stringify(testArr));
 # --solutions--
 
 ```js
-var testArr = [ 1,2,3,4,5];
+const testArr = [1, 2, 3, 4, 5];
 
 function nextInLine(arr, item) {
     arr.push(item);
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md
index 4b1cab278e7..20adb9f4aea 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md
@@ -14,7 +14,7 @@ dashedName: store-multiple-values-in-one-variable-using-javascript-arrays
 以左方括號開始定義一個數組，以右方括號結束，裏面每個元素之間用逗號隔開，例如：
 
 ```js
-var sandwich = ["peanut butter", "jelly", "bread"]
+const sandwich = ["peanut butter", "jelly", "bread"];
 ```
 
 # --instructions--
@@ -53,11 +53,11 @@ assert(typeof myArray[1] !== 'undefined' && typeof myArray[1] == 'number');
 
 ```js
 // Only change code below this line
-var myArray = [];
+const myArray = [];
 ```
 
 # --solutions--
 
 ```js
-var myArray = ["The Answer", 42];
+const myArray = ["The Answer", 42];
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md
index 21f07ef062b..bf077920297 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md
@@ -16,7 +16,7 @@ JavaScript 中使用 `-` 來做減法運算。
 **示例**
 
 ```js
-myVar = 12 - 6;
+const myVar = 12 - 6;
 ```
 
 現在，變量 `myVar` 的值爲 `6`。
@@ -49,11 +49,11 @@ assert(/difference=45-33;?/.test(__helpers.removeWhiteSpace(code)));
 ## --seed-contents--
 
 ```js
-var difference = 45 - 0;
+const difference = 45 - 0;
 ```
 
 # --solutions--
 
 ```js
-var difference = 45 - 33;
+const difference = 45 - 33;
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md
index 30d0d643976..33d21dcdec6 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md
@@ -13,10 +13,11 @@ dashedName: testing-objects-for-properties
 **示例**
 
 ```js
-var myObj = {
+const myObj = {
   top: "hat",
   bottom: "pants"
 };
+
 myObj.hasOwnProperty("top");
 myObj.hasOwnProperty("middle");
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md
index fa573f673e2..bb5ae04a5f0 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md
@@ -14,14 +14,14 @@ dashedName: understand-string-immutability
 例如，下面的代碼：
 
 ```js
-var myStr = "Bob";
+let myStr = "Bob";
 myStr[0] = "J";
 ```
 
 是不會把變量 `myStr` 的值改變成 `Job` 的，因爲變量 `myStr` 是不可變的。 注意，這*並不*意味着 `myStr` 永遠不能被改變，只是字符串字面量 <dfn>string literal</dfn> 的各個字符不能被改變。 改變 `myStr` 的唯一方法是重新給它賦一個值，例如：
 
 ```js
-var myStr = "Bob";
+let myStr = "Bob";
 myStr = "Job";
 ```
 
@@ -55,7 +55,7 @@ assert(/myStr = "Jello World"/.test(code));
 
 ```js
 // Setup
-var myStr = "Jello World";
+let myStr = "Jello World";
 
 // Only change code below this line
 myStr[0] = "H"; // Change this line
@@ -65,6 +65,6 @@ myStr[0] = "H"; // Change this line
 # --solutions--
 
 ```js
-var myStr = "Jello World";
+let myStr = "Jello World";
 myStr = "Hello World";
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md
index ef14a2c5e6b..1576a1570dd 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md
@@ -43,7 +43,6 @@ welcomeToBooleans();
 
 ```js
 function welcomeToBooleans() {
-
   // Only change code below this line
 
   return false; // Change this line
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md
index 269618c331c..994779472a6 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md
@@ -14,10 +14,12 @@ dashedName: understanding-undefined-value-returned-from-a-function
 **示例**
 
 ```js
-var sum = 0;
+let sum = 0;
+
 function addSum(num) {
   sum = sum + num;
 }
+
 addSum(3);
 ```
 
@@ -61,7 +63,7 @@ assert(
 
 ```js
 // Setup
-var sum = 0;
+let sum = 0;
 
 function addThree() {
   sum = sum + 3;
@@ -79,7 +81,7 @@ addFive();
 # --solutions--
 
 ```js
-var sum = 0;
+let sum = 0;
 
 function addThree() {
   sum = sum + 3;
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md
index f16bd068ac3..93c13e9e31c 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md
@@ -14,7 +14,7 @@ dashedName: updating-object-properties
 舉個例子，讓我們看看 `ourDog`：
 
 ```js
-var ourDog = {
+const ourDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
@@ -54,7 +54,7 @@ assert(/"name": "Coder"/.test(code));
 
 ```js
 // Setup
-var myDog = {
+const myDog = {
   "name": "Coder",
   "legs": 4,
   "tails": 1,
@@ -62,12 +62,13 @@ var myDog = {
 };
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Coder",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md
index 3c0dc492846..b48a3627a5e 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md
@@ -16,8 +16,8 @@ dashedName: use-bracket-notation-to-find-the-nth-character-in-a-string
 例如：
 
 ```js
-var firstName = "Ada";
-var secondLetterOfFirstName = firstName[1];
+const firstName = "Ada";
+const secondLetterOfFirstName = firstName[1];
 ```
 
 `secondLetterOfFirstName` 值應該爲字符串 `d`。
@@ -54,15 +54,15 @@ assert(code.match(/thirdLetterOfLastName\s*?=\s*?lastName\[.*?\]/));
 
 ```js
 // Setup
-var lastName = "Lovelace";
+const lastName = "Lovelace";
 
 // Only change code below this line
-var thirdLetterOfLastName = lastName; // Change this line
+const thirdLetterOfLastName = lastName; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var lastName = "Lovelace";
-var thirdLetterOfLastName = lastName[2];
+const lastName = "Lovelace";
+const thirdLetterOfLastName = lastName[2];
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md
index 3f90aeba41b..5cc0098b523 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md
@@ -73,7 +73,7 @@ function rangeOfNumbers(startNum, endNum) {
   if (endNum - startNum === 0) {
     return [startNum];
   } else {
-    var numbers = rangeOfNumbers(startNum, endNum - 1);
+    const numbers = rangeOfNumbers(startNum, endNum - 1);
     numbers.push(endNum);
     return numbers;
   }
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md
index 609ac68da9e..c88f18ce8c1 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md
@@ -20,7 +20,7 @@ parseInt(string, radix);
 這是一個示例：
 
 ```js
-var a = parseInt("11", 2);
+const a = parseInt("11", 2);
 ```
 
 變量 radix 表示 `11` 是在二進制系統中。 這個示例將字符串 `11` 轉換爲整數 `3`。
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md
index 67934c4d259..43c13f31a2e 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md
@@ -12,7 +12,7 @@ dashedName: use-the-parseint-function
 `parseInt()` 函數解析一個字符串返回一個整數。 下面是一個示例：
 
 ```js
-var a = parseInt("007");
+const a = parseInt("007");
 ```
 
 上述函數將字符串 `007` 轉換爲整數 `7`。 如果字符串中的第一個字符不能轉換爲數字，則返回 `NaN`。
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md
index 0e12a759818..009bbea997d 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md
@@ -14,7 +14,7 @@ dashedName: using-objects-for-lookups
 這是簡單的反向字母表：
 
 ```js
-var alpha = {
+const alpha = {
   1:"Z",
   2:"Y",
   3:"X",
@@ -24,10 +24,11 @@ var alpha = {
   25:"B",
   26:"A"
 };
+
 alpha[2];
 alpha[24];
 
-var value = 2;
+const value = 2;
 alpha[value];
 ```
 
@@ -102,7 +103,7 @@ assert(
 ```js
 // Setup
 function phoneticLookup(val) {
-  var result = "";
+  let result = "";
 
   // Only change code below this line
   switch(val) {
@@ -136,9 +137,9 @@ phoneticLookup("charlie");
 
 ```js
 function phoneticLookup(val) {
-  var result = "";
+  let result = "";
 
-  var lookup = {
+  const lookup = {
     alpha: "Adams",
     bravo: "Boston",
     charlie: "Chicago",
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md
index 533e82a3dd0..23a1655c388 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md
@@ -16,7 +16,7 @@ dashedName: word-blanks
 思考一下這句話 - It was really **\_\_\_\_**, and we **\_\_\_\_** ourselves **\_\_\_\_**。 這句話有三個缺失的部分 - 形容詞、動詞和副詞，選擇合適單詞填入完成它。 然後將完成的句子賦值給變量，如下所示：
 
 ```js
-var sentence = "It was really " + "hot" + ", and we " + "laughed" + " ourselves " + "silly" + ".";
+const sentence = "It was really " + "hot" + ", and we " + "laughed" + " ourselves " + "silly" + ".";
 ```
 
 # --instructions--
@@ -84,24 +84,24 @@ const removeAssignments = str => str
 ## --seed-contents--
 
 ```js
-var myNoun = "dog";
-var myAdjective = "big";
-var myVerb = "ran";
-var myAdverb = "quickly";
+const myNoun = "dog";
+const myAdjective = "big";
+const myVerb = "ran";
+const myAdverb = "quickly";
 
 // Only change code below this line
-var wordBlanks = ""; // Change this line
+const wordBlanks = ""; // Change this line
 // Only change code above this line
 ```
 
 # --solutions--
 
 ```js
-var myNoun = "dog";
-var myAdjective = "big";
-var myVerb = "ran";
-var myAdverb = "quickly";
+const myNoun = "dog";
+const myAdjective = "big";
+const myVerb = "ran";
+const myAdverb = "quickly";
 
-var wordBlanks = "Once there was a " + myNoun + " which was very " + myAdjective + ". ";
+let wordBlanks = "Once there was a " + myNoun + " which was very " + myAdjective + ". ";
 wordBlanks += "It " + myVerb + " " + myAdverb + " around the yard.";
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md
index ed76e10d956..3383a8029ef 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md
@@ -13,7 +13,7 @@ dashedName: add-elements-to-the-end-of-an-array-using-concat-instead-of-push
 上一個挑戰介紹了 `concat` 方法，這是一種在不改變原始數組的前提下，將數組組合成新數組的方法。 將 `concat` 方法與 `push` 方法做比較。 `push` 將元素添加到調用它的數組的末尾，這樣會改變該數組。 舉個例子：
 
 ```js
-var arr = [1, 2, 3];
+const arr = [1, 2, 3];
 arr.push([4, 5, 6]);
 ```
 
@@ -71,8 +71,9 @@ function nonMutatingPush(original, newItem) {
 
   // Only change code above this line
 }
-var first = [1, 2, 3];
-var second = [4, 5];
+
+const first = [1, 2, 3];
+const second = [4, 5];
 nonMutatingPush(first, second);
 ```
 
@@ -82,7 +83,6 @@ nonMutatingPush(first, second);
 function nonMutatingPush(original, newItem) {
   return original.concat(newItem);
 }
-var first = [1, 2, 3];
-var second = [4, 5];
-nonMutatingPush(first, second);
+const first = [1, 2, 3];
+const second = [4, 5];
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md
index bb8fd388318..ff01baf7936 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md
@@ -77,7 +77,6 @@ function urlSlug(title) {
 # --solutions--
 
 ```js
-// Only change code below this line
 function urlSlug(title) {
   return title.trim().split(/\s+/).join("-").toLowerCase();
 }
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md
index 3f67e299b9b..da3c0c94be7 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md
@@ -57,9 +57,9 @@ assert(__newValue === 5);
 
 ```js
 // The global variable
-var fixedValue = 4;
+let fixedValue = 4;
 
-function incrementer () {
+function incrementer() {
   // Only change code below this line
 
 
@@ -70,7 +70,7 @@ function incrementer () {
 # --solutions--
 
 ```js
-var fixedValue = 4
+let fixedValue = 4
 
 function incrementer() {
   return fixedValue + 1
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md
index f82e007c384..b2f4eda2d72 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md
@@ -13,8 +13,8 @@ dashedName: combine-an-array-into-a-string-using-the-join-method
 舉個例子：
 
 ```js
-var arr = ["Hello", "World"];
-var str = arr.join(" ");
+const arr = ["Hello", "World"];
+const str = arr.join(" ");
 ```
 
 `str` 的值應該是字符串 `Hello World`。
@@ -76,6 +76,7 @@ function sentensify(str) {
 
   // Only change code above this line
 }
+
 sentensify("May-the-force-be-with-you");
 ```
 
@@ -83,8 +84,6 @@ sentensify("May-the-force-be-with-you");
 
 ```js
 function sentensify(str) {
-  // Only change code below this line
   return str.split(/\W/).join(' ');
-  // Only change code above this line
 }
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md
index 92a0001506f..c82569f3d61 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md
@@ -60,8 +60,9 @@ function nonMutatingConcat(original, attach) {
 
   // Only change code above this line
 }
-var first = [1, 2, 3];
-var second = [4, 5];
+
+const first = [1, 2, 3];
+const second = [4, 5];
 nonMutatingConcat(first, second);
 ```
 
@@ -69,11 +70,8 @@ nonMutatingConcat(first, second);
 
 ```js
 function nonMutatingConcat(original, attach) {
-  // Only change code below this line
   return original.concat(attach);
-  // Only change code above this line
 }
-var first = [1, 2, 3];
-var second = [4, 5];
-nonMutatingConcat(first, second);
+const first = [1, 2, 3];
+const second = [4, 5];
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md
index 426f31fe7ed..7fc976d2512 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md
@@ -38,17 +38,17 @@ assert(!code.match(/\.?[\s\S]*?map/g));
 
 ```js
 // The global variable
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myMap = function(callback) {
-  var newArray = [];
+  const newArray = [];
   // Only change code below this line
 
   // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myMap(function(item) {
+const new_s = s.myMap(function(item) {
   return item * 2;
 });
 ```
@@ -56,20 +56,17 @@ var new_s = s.myMap(function(item) {
 # --solutions--
 
 ```js
-// the global Array
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myMap = function(callback) {
-  var newArray = [];
-  // Only change code below this line
-  for (var elem of this) {
+  const newArray = [];
+  for (const elem of this) {
     newArray.push(callback(elem));
   }
-  // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myMap(function(item) {
+const new_s = s.myMap(function(item) {
   return item * 2;
 });
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md
index 1e565f7af01..0f1123713d5 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md
@@ -34,16 +34,16 @@ assert(!code.match(/\.?[\s\S]*?filter/g));
 
 ```js
 // The global variable
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myFilter = function(callback) {
   // Only change code below this line
-  var newArray = [];
+  const newArray = [];
   // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myFilter(function(item) {
+const new_s = s.myFilter(function(item) {
   return item % 2 === 1;
 });
 ```
@@ -51,20 +51,17 @@ var new_s = s.myFilter(function(item) {
 # --solutions--
 
 ```js
-// the global Array
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myFilter = function(callback) {
-  var newArray = [];
-  // Only change code below this line
+  const newArray = [];
   for (let i = 0; i < this.length; i++) {
     if (callback(this[i])) newArray.push(this[i]);
   }
-  // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myFilter(function(item) {
+const new_s = s.myFilter(function(item) {
   return item % 2 === 1;
 });
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md
index 26f1ee66528..21c948e08ee 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md
@@ -35,7 +35,7 @@ curried(1)(2)
 柯里化在不能一次爲函數提供所有參數情況下很有用。 因爲它可以將每個函數的調用保存到一個變量中，該變量將保存返回的函數引用，該引用在下一個參數可用時接受該參數。 下面是使用柯里化函數的例子：
 
 ```js
-var funcForY = curried(1);
+const funcForY = curried(1);
 console.log(funcForY(2)); // 3
 ```
 
@@ -45,7 +45,8 @@ console.log(funcForY(2)); // 3
 function impartial(x, y, z) {
   return x + y + z;
 }
-var partialFn = impartial.bind(this, 1, 2);
+
+const partialFn = impartial.bind(this, 1, 2);
 partialFn(10); // 13
 ```
 
@@ -90,6 +91,7 @@ function add(x) {
 
   // Only change code above this line
 }
+
 add(10)(20)(30);
 ```
 
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md
index 6364e9d889d..e04f7f830be 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md
@@ -53,10 +53,10 @@ assert(__newValue === 5);
 
 ```js
 // The global variable
-var fixedValue = 4;
+let fixedValue = 4;
 
 // Only change code below this line
-function incrementer () {
+function incrementer() {
 
 
   // Only change code above this line
@@ -66,15 +66,9 @@ function incrementer () {
 # --solutions--
 
 ```js
-// The global variable
-var fixedValue = 4;
+let fixedValue = 4;
 
-// Only change code below this line
-function incrementer (fixedValue) {
+function incrementer(fixedValue) {
   return fixedValue + 1;
-
-  // Only change code above this line
 }
-
-
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md
index b739782b24c..021e6b4b212 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md
@@ -11,7 +11,7 @@ dashedName: remove-elements-from-an-array-using-slice-instead-of-splice
 使用數組時經常遇到要刪除一些元素並保留數組剩餘部分的情況。 爲此，JavaScript 提供了 `splice` 方法，它接收兩個參數：從哪裏開始刪除項目的索引，和要刪除的項目數。 如果沒有提供第二個參數，默認情況下是移除一直到結尾的所有元素。 但 `splice` 方法會改變調用它的原始數組。 舉個例子：
 
 ```js
-var cities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
+const cities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
 cities.splice(3, 1);
 ```
 
@@ -69,7 +69,8 @@ function nonMutatingSplice(cities) {
 
   // Only change code above this line
 }
-var inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
+
+const inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
 nonMutatingSplice(inputCities);
 ```
 
@@ -77,10 +78,7 @@ nonMutatingSplice(inputCities);
 
 ```js
 function nonMutatingSplice(cities) {
-  // Only change code below this line
   return cities.slice(0,3);
-  // Only change code above this line
 }
-var inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
-nonMutatingSplice(inputCities);
+const inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md
index d8aed83b75f..f4da66801de 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md
@@ -68,24 +68,23 @@ assert(JSON.stringify(nonMutatingSort([140000, 104, 99])) ===
 ## --seed-contents--
 
 ```js
-var globalArray = [5, 6, 3, 2, 9];
+const globalArray = [5, 6, 3, 2, 9];
+
 function nonMutatingSort(arr) {
   // Only change code below this line
 
 
   // Only change code above this line
 }
+
 nonMutatingSort(globalArray);
 ```
 
 # --solutions--
 
 ```js
-var globalArray = [5, 6, 3, 2, 9];
+const globalArray = [5, 6, 3, 2, 9];
 function nonMutatingSort(arr) {
-  // Only change code below this line
   return [].concat(arr).sort((a,b) => a-b);
-  // Only change code above this line
 }
-nonMutatingSort(globalArray);
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md
index 4f2bc17be29..e096a3d94a9 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md
@@ -13,8 +13,8 @@ dashedName: return-part-of-an-array-using-the-slice-method
 舉個例子：
 
 ```js
-var arr = ["Cat", "Dog", "Tiger", "Zebra"];
-var newArray = arr.slice(1, 3);
+const arr = ["Cat", "Dog", "Tiger", "Zebra"];
+const newArray = arr.slice(1, 3);
 ```
 
 `newArray` 值爲 `["Dog", "Tiger"]`
@@ -78,7 +78,8 @@ function sliceArray(anim, beginSlice, endSlice) {
 
   // Only change code above this line
 }
-var inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
+
+const inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
 sliceArray(inputAnim, 1, 3);
 ```
 
@@ -86,10 +87,7 @@ sliceArray(inputAnim, 1, 3);
 
 ```js
 function sliceArray(anim, beginSlice, endSlice) {
-  // Only change code below this line
-  return anim.slice(beginSlice, endSlice)
-  // Only change code above this line
+  return anim.slice(beginSlice, endSlice);
 }
-var inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
-sliceArray(inputAnim, 1, 3);
+const inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md
index 81fe51f009d..cf6eedde997 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md
@@ -18,6 +18,7 @@ function ascendingOrder(arr) {
     return a - b;
   });
 }
+
 ascendingOrder([1, 5, 2, 3, 4]);
 ```
 
@@ -29,6 +30,7 @@ function reverseAlpha(arr) {
     return a === b ? 0 : a < b ? 1 : -1;
   });
 }
+
 reverseAlpha(['l', 'h', 'z', 'b', 's']);
 ```
 
@@ -86,6 +88,7 @@ function alphabeticalOrder(arr) {
   return arr
   // Only change code above this line
 }
+
 alphabeticalOrder(["a", "d", "c", "a", "z", "g"]);
 ```
 
@@ -93,9 +96,6 @@ alphabeticalOrder(["a", "d", "c", "a", "z", "g"]);
 
 ```js
 function alphabeticalOrder(arr) {
-  // Only change code below this line
   return arr.sort();
-  // Only change code above this line
 }
-alphabeticalOrder(["a", "d", "c", "a", "z", "g"]);
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md
index f7fd1cfc07a..1aba206b00a 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md
@@ -13,11 +13,11 @@ dashedName: split-a-string-into-an-array-using-the-split-method
 下面是兩個用空格分隔一個字符串的例子，另一個是用數字的正則表達式分隔：
 
 ```js
-var str = "Hello World";
-var bySpace = str.split(" ");
+const str = "Hello World";
+const bySpace = str.split(" ");
 
-var otherString = "How9are7you2today";
-var byDigits = otherString.split(/\d/);
+const otherString = "How9are7you2today";
+const byDigits = otherString.split(/\d/);
 ```
 
 `bySpace` 將有值 `["Hello", "World"]`，`byDigits` 將有值 `["How", "are", "you", "today"]`。
@@ -74,6 +74,7 @@ function splitify(str) {
 
   // Only change code above this line
 }
+
 splitify("Hello World,I-am code");
 ```
 
@@ -81,8 +82,6 @@ splitify("Hello World,I-am code");
 
 ```js
 function splitify(str) {
-  // Only change code below this line
   return str.split(/\W/);
-  // Only change code above this line
 }
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md
index 86fdcb59989..f84d095601d 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md
@@ -59,29 +59,29 @@ assert.deepEqual(finalTabs.tabs, [
 
 ```js
 // tabs is an array of titles of each site open within the window
-var Window = function(tabs) {
+const Window = function(tabs) {
   this.tabs = tabs; // We keep a record of the array inside the object
 };
 
 // When you join two windows into one window
-Window.prototype.join = function (otherWindow) {
+Window.prototype.join = function(otherWindow) {
   this.tabs = this.tabs.concat(otherWindow.tabs);
   return this;
 };
 
 // When you open a new tab at the end
-Window.prototype.tabOpen = function (tab) {
+Window.prototype.tabOpen = function(tab) {
   this.tabs.push('new tab'); // Let's open a new tab for now
   return this;
 };
 
 // When you close a tab
-Window.prototype.tabClose = function (index) {
+Window.prototype.tabClose = function(index) {
 
   // Only change code below this line
 
-  var tabsBeforeIndex = this.tabs.splice(0, index); // Get the tabs before the tab
-  var tabsAfterIndex = this.tabs.splice(index + 1); // Get the tabs after the tab
+  const tabsBeforeIndex = this.tabs.splice(0, index); // Get the tabs before the tab
+  const tabsAfterIndex = this.tabs.splice(index + 1); // Get the tabs after the tab
 
   this.tabs = tabsBeforeIndex.concat(tabsAfterIndex); // Join them together
 
@@ -91,12 +91,12 @@ Window.prototype.tabClose = function (index) {
  };
 
 // Let's create three browser windows
-var workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']); // Your mailbox, drive, and other work sites
-var socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']); // Social sites
-var videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']); // Entertainment sites
+const workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']); // Your mailbox, drive, and other work sites
+const socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']); // Social sites
+const videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']); // Entertainment sites
 
 // Now perform the tab opening, closing, and other operations
-var finalTabs = socialWindow
+const finalTabs = socialWindow
   .tabOpen() // Open a new tab for cat memes
   .join(videoWindow.tabClose(2)) // Close third tab in video window, and join
   .join(workWindow.tabClose(1).tabOpen());
@@ -106,40 +106,34 @@ console.log(finalTabs.tabs);
 # --solutions--
 
 ```js
-// tabs is an array of titles of each site open within the window
-var Window = function(tabs) {
-  this.tabs = tabs; // We keep a record of the array inside the object
+const Window = function(tabs) {
+  this.tabs = tabs;
 };
 
-// When you join two windows into one window
-Window.prototype.join = function (otherWindow) {
+Window.prototype.join = function(otherWindow) {
   this.tabs = this.tabs.concat(otherWindow.tabs);
   return this;
 };
 
-// When you open a new tab at the end
-Window.prototype.tabOpen = function (tab) {
-  this.tabs.push('new tab'); // Let's open a new tab for now
+Window.prototype.tabOpen = function(tab) {
+  this.tabs.push('new tab');
   return this;
 };
 
-// When you close a tab
-Window.prototype.tabClose = function (index) {
-  var tabsBeforeIndex = this.tabs.slice(0, index); // Get the tabs before the tab
-  var tabsAfterIndex = this.tabs.slice(index + 1); // Get the tabs after the tab
+Window.prototype.tabClose = function(index) {
+  const tabsBeforeIndex = this.tabs.slice(0, index);
+  const tabsAfterIndex = this.tabs.slice(index + 1);
 
-  this.tabs = tabsBeforeIndex.concat(tabsAfterIndex); // Join them together
+  this.tabs = tabsBeforeIndex.concat(tabsAfterIndex);
   return this;
  };
 
-// Let's create three browser windows
-var workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']); // Your mailbox, drive, and other work sites
-var socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']); // Social sites
-var videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']); //  Entertainment sites
+const workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']);
+const socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']);
+const videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']);
 
-// Now perform the tab opening, closing, and other operations
-var finalTabs = socialWindow
-  .tabOpen() // Open a new tab for cat memes
-  .join(videoWindow.tabClose(2)) // Close third tab in video window, and join
+const finalTabs = socialWindow
+  .tabOpen()
+  .join(videoWindow.tabClose(2))
   .join(workWindow.tabClose(1).tabOpen());
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md
index 1cf1fad9260..8de8e231b88 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md
@@ -13,7 +13,8 @@ dashedName: use-the-every-method-to-check-that-every-element-in-an-array-meets-a
 舉個例子，下面的代碼檢測數組 `numbers` 的所有元素是否都小於 10：
 
 ```js
-var numbers = [1, 5, 8, 0, 10, 11];
+const numbers = [1, 5, 8, 0, 10, 11];
+
 numbers.every(function(currentValue) {
   return currentValue < 10;
 });
@@ -62,6 +63,7 @@ function checkPositive(arr) {
 
   // Only change code above this line
 }
+
 checkPositive([1, 2, 3, -4, 5]);
 ```
 
@@ -69,9 +71,6 @@ checkPositive([1, 2, 3, -4, 5]);
 
 ```js
 function checkPositive(arr) {
-  // Only change code below this line
   return arr.every(num => num > 0);
-  // Only change code above this line
 }
-checkPositive([1, 2, 3, -4, 5]);
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md
index eda4082cfb6..c0a6bb9b8b5 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md
@@ -93,7 +93,7 @@ assert(getRating(watchList.filter((_, i) => i < 1 || i > 2)) === 8.55);
 
 ```js
 // The global variable
-var watchList = [
+const watchList = [
   {
     "Title": "Inception",
     "Year": "2010",
@@ -206,22 +206,22 @@ var watchList = [
   }
 ];
 
-function getRating(watchList){
+function getRating(watchList) {
   // Only change code below this line
-  var averageRating;
+  let averageRating;
 
 
   // Only change code above this line
   return averageRating;
 }
+
 console.log(getRating(watchList));
 ```
 
 # --solutions--
 
 ```js
-// The global variable
-var watchList = [
+const watchList = [
   {
     "Title": "Inception",
     "Year": "2010",
@@ -334,8 +334,8 @@ var watchList = [
   }
 ];
 
-function getRating(watchList){
-  var averageRating;
+function getRating(watchList) {
+  let averageRating;
   const rating = watchList
     .filter(obj => obj.Director === "Christopher Nolan")
     .map(obj => Number(obj.imdbRating));
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md
index 47ab582cfb5..ed2c5c9b4d5 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md
@@ -13,7 +13,8 @@ dashedName: use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-cr
 舉個例子，下面的代碼檢測數組`numbers`中是否有元素小於 10：
 
 ```js
-var numbers = [10, 50, 8, 220, 110, 11];
+const numbers = [10, 50, 8, 220, 110, 11];
+
 numbers.some(function(currentValue) {
   return currentValue < 10;
 });
@@ -62,6 +63,7 @@ function checkPositive(arr) {
 
   // Only change code above this line
 }
+
 checkPositive([1, 2, 3, -4, 5]);
 ```
 
@@ -69,9 +71,6 @@ checkPositive([1, 2, 3, -4, 5]);
 
 ```js
 function checkPositive(arr) {
-  // Only change code below this line
   return arr.some(elem => elem > 0);
-  // Only change code above this line
 }
-checkPositive([1, 2, 3, -4, 5]);
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md
index 24c0a00232b..7e65e01cab9 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md
@@ -157,7 +157,7 @@ assert(diffArray([1, 'calf', 3, 'piglet'], [7, 'filly']).length === 6);
 
 ```js
 function diffArray(arr1, arr2) {
-  var newArr = [];
+  const newArr = [];
   return newArr;
 }
 
@@ -168,13 +168,12 @@ diffArray([1, 2, 3, 5], [1, 2, 3, 4, 5]);
 
 ```js
 function diffArray(arr1, arr2) {
-  var newArr = [];
-  var h1 = Object.create(null);
+  const newArr = [];
+  const h1 = Object.create(null);
   arr1.forEach(function(e) {
     h1[e] = e;
   });
-
-  var h2 = Object.create(null);
+  const h2 = Object.create(null);
   arr2.forEach(function(e) {
     h2[e] = e;
   });
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md
index 6110cd3116e..08d60e17b9d 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md
@@ -148,7 +148,7 @@ if(bob){
 ## --seed-contents--
 
 ```js
-var Person = function(firstAndLast) {
+const Person = function(firstAndLast) {
   // Only change code below this line
   // Complete the method below and implement the others similarly
   this.getFullName = function() {
@@ -157,16 +157,16 @@ var Person = function(firstAndLast) {
   return firstAndLast;
 };
 
-var bob = new Person('Bob Ross');
+const bob = new Person('Bob Ross');
 bob.getFullName();
 ```
 
 # --solutions--
 
 ```js
-var Person = function(firstAndLast) {
+const Person = function(firstAndLast) {
 
-  var firstName, lastName;
+  let firstName, lastName;
 
   function updateName(str) {
     firstName = str.split(" ")[0];
@@ -201,6 +201,6 @@ var Person = function(firstAndLast) {
   };
 };
 
-var bob = new Person('Bob Ross');
+const bob = new Person('Bob Ross');
 bob.getFullName();
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md
index 47eca199152..821ecee1b1f 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md
@@ -51,8 +51,8 @@ assert.deepEqual(
 
 ```js
 function orbitalPeriod(arr) {
-  var GM = 398600.4418;
-  var earthRadius = 6367.4447;
+  const GM = 398600.4418;
+  const earthRadius = 6367.4447;
   return arr;
 }
 
@@ -63,9 +63,9 @@ orbitalPeriod([{name : "sputnik", avgAlt : 35873.5553}]);
 
 ```js
 function orbitalPeriod(arr) {
-  var GM = 398600.4418;
-  var earthRadius = 6367.4447;
-  var TAU = 2 * Math.PI;
+  const GM = 398600.4418;
+  const earthRadius = 6367.4447;
+  const TAU = 2 * Math.PI;
   return arr.map(function(obj) {
     return {
       name: obj.name,
@@ -73,6 +73,4 @@ function orbitalPeriod(arr) {
     };
   });
 }
-
-orbitalPeriod([{name : "sputkin", avgAlt : 35873.5553}]);
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md
index 62fc10e71e1..4dae74b41f2 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md
@@ -61,7 +61,6 @@ function smallestCommons(arr) {
   return arr;
 }
 
-
 smallestCommons([1,5]);
 ```
 
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md
index 8eef2dc2a15..5d956b6180a 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md
@@ -103,7 +103,7 @@ assert.deepEqual(
 
 ```js
 function whatIsInAName(collection, source) {
-  var arr = [];
+  const arr = [];
   // Only change code below this line
 
 
@@ -118,8 +118,8 @@ whatIsInAName([{ first: "Romeo", last: "Montague" }, { first: "Mercutio", last:
 
 ```js
 function whatIsInAName(collection, source) {
-  var arr = [];
-  var keys = Object.keys(source);
+  const arr = [];
+  const keys = Object.keys(source);
   collection.forEach(function(e) {
     if(keys.every(function(key) {return e[key] === source[key];})) {
       arr.push(e);
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md
index 0348981cd08..95ec7c77778 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md
@@ -51,7 +51,6 @@ assert(
 
 ```js
 function rot13(str) {
-
   return str;
 }
 
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md
index ae714a75161..2bf9d2d76cf 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md
@@ -186,7 +186,7 @@ assert.deepEqual(
 
 ```js
 function checkCashRegister(price, cash, cid) {
-  var change;
+  let change;
   return change;
 }
 
@@ -196,54 +196,57 @@ checkCashRegister(19.5, 20, [["PENNY", 1.01], ["NICKEL", 2.05], ["DIME", 3.1], [
 # --solutions--
 
 ```js
-var denom = [
-    { name: 'ONE HUNDRED', val: 100},
-    { name: 'TWENTY', val: 20},
-    { name: 'TEN', val: 10},
-    { name: 'FIVE', val: 5},
-    { name: 'ONE', val: 1},
-    { name: 'QUARTER', val: 0.25},
-    { name: 'DIME', val: 0.1},
-    { name: 'NICKEL', val: 0.05},
-    { name: 'PENNY', val: 0.01}
+const denom = [
+  { name: "ONE HUNDRED", val: 100 },
+  { name: "TWENTY", val: 20 },
+  { name: "TEN", val: 10 },
+  { name: "FIVE", val: 5 },
+  { name: "ONE", val: 1 },
+  { name: "QUARTER", val: 0.25 },
+  { name: "DIME", val: 0.1 },
+  { name: "NICKEL", val: 0.05 },
+  { name: "PENNY", val: 0.01 },
 ];
 
 function checkCashRegister(price, cash, cid) {
- var output = {status: null, change: []};
- var change = cash - price;
- var register = cid.reduce(function(acc, curr) {
- acc.total += curr[1];
- acc[curr[0]] = curr[1];
- return acc;
- }, {total: 0});
- if(register.total === change) {
- output.status = 'CLOSED';
- output.change = cid;
- return output;
- }
- if(register.total < change) {
- output.status = 'INSUFFICIENT_FUNDS';
- return output;
- }
- var change_arr = denom.reduce(function(acc, curr) {
- var value = 0;
- while(register[curr.name] > 0 && change >= curr.val) {
- change -= curr.val;
- register[curr.name] -= curr.val;
- value += curr.val;
- change = Math.round(change * 100) / 100;
- }
- if(value > 0) {
- acc.push([ curr.name, value ]);
- }
- return acc;
- }, []);
- if(change_arr.length < 1 || change > 0) {
- output.status = 'INSUFFICIENT_FUNDS';
- return output;
- }
- output.status = 'OPEN';
- output.change = change_arr;
- return output;
+  const output = { status: null, change: [] };
+  let change = cash - price;
+  const register = cid.reduce(
+    function (acc, curr) {
+      acc.total += curr[1];
+      acc[curr[0]] = curr[1];
+      return acc;
+    },
+    { total: 0 }
+  );
+  if (register.total === change) {
+    output.status = "CLOSED";
+    output.change = cid;
+    return output;
+  }
+  if (register.total < change) {
+    output.status = "INSUFFICIENT_FUNDS";
+    return output;
+  }
+  const change_arr = denom.reduce(function (acc, curr) {
+    let value = 0;
+    while (register[curr.name] > 0 && change >= curr.val) {
+      change -= curr.val;
+      register[curr.name] -= curr.val;
+      value += curr.val;
+      change = Math.round(change * 100) / 100;
+    }
+    if (value > 0) {
+      acc.push([curr.name, value]);
+    }
+    return acc;
+  }, []);
+  if (change_arr.length < 1 || change > 0) {
+    output.status = "INSUFFICIENT_FUNDS";
+    return output;
+  }
+  output.status = "OPEN";
+  output.change = change_arr;
+  return output;
 }
 ```
diff --git a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md
index 75fbd433a3b..df93db6b181 100644
--- a/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md
+++ b/curriculum/challenges/chinese-traditional/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md
@@ -107,8 +107,6 @@ function palindrome(str) {
   return true;
 }
 
-
-
 palindrome("eye");
 ```
 
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md
index ff44d0b7de6..49d0771b122 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md
@@ -18,9 +18,9 @@ dashedName: access-array-data-with-indexes
 **示例**
 
 ```js
-var array = [50,60,70];
+const array = [50, 60, 70];
 array[0];
-var data = array[1];
+const data = array[1];
 ```
 
 现在 `array[0]` 的值是 `50`， `data` 的值为 `60`.
@@ -76,7 +76,7 @@ if(typeof myArray !== "undefined" && typeof myData !== "undefined"){(function(y,
 ## --seed-contents--
 
 ```js
-var myArray = [50,60,70];
+const myArray = [50, 60, 70];
 
 
 ```
@@ -84,6 +84,6 @@ var myArray = [50,60,70];
 # --solutions--
 
 ```js
-var myArray = [50,60,70];
-var myData = myArray[0];
+const myArray = [50, 60, 70];
+const myData = myArray[0];
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md
index 4c81c928bb4..f59a45b5753 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md
@@ -14,12 +14,13 @@ dashedName: access-multi-dimensional-arrays-with-indexes
 **例如：**
 
 ```js
-var arr = [
-  [1,2,3],
-  [4,5,6],
-  [7,8,9],
-  [[10,11,12], 13, 14]
+const arr = [
+  [1, 2, 3],
+  [4, 5, 6],
+  [7, 8, 9],
+  [[10, 11, 12], 13, 14]
 ];
+
 arr[3];
 arr[3][0];
 arr[3][0][1];
@@ -58,14 +59,19 @@ if(typeof myArray !== "undefined"){(function(){return "myData: " + myData + " my
 ## --seed-contents--
 
 ```js
-var myArray = [[1,2,3], [4,5,6], [7,8,9], [[10,11,12], 13, 14]];
+const myArray = [
+  [1, 2, 3],
+  [4, 5, 6],
+  [7, 8, 9],
+  [[10, 11, 12], 13, 14],
+];
 
-var myData = myArray[0][0];
+const myData = myArray[0][0];
 ```
 
 # --solutions--
 
 ```js
-var myArray = [[1,2,3],[4,5,6], [7,8,9], [[10,11,12], 13, 14]];
-var myData = myArray[2][1];
+const myArray = [[1, 2, 3], [4, 5, 6], [7, 8, 9], [[10, 11, 12], 13, 14]];
+const myData = myArray[2][1];
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md
index 5bc88691fac..d1fd1a4a5ef 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md
@@ -14,7 +14,7 @@ dashedName: accessing-nested-arrays
 下面是访问嵌套数组的例子：
 
 ```js
-var ourPets = [
+const ourPets = [
   {
     animalType: "cat",
     names: [
@@ -32,6 +32,7 @@ var ourPets = [
     ]
   }
 ];
+
 ourPets[0].names[1];
 ourPets[1].names[0];
 ```
@@ -72,7 +73,7 @@ assert(/=\s*myPlants\[1\].list\[1\]/.test(code));
 ## --seed-contents--
 
 ```js
-var myPlants = [
+const myPlants = [
   {
     type: "flowers",
     list: [
@@ -91,13 +92,13 @@ var myPlants = [
   }
 ];
 
-var secondTree = "";
+const secondTree = "";
 ```
 
 # --solutions--
 
 ```js
-var myPlants = [
+const myPlants = [
   {
     type: "flowers",
     list: [
@@ -116,5 +117,5 @@ var myPlants = [
   }
 ];
 
-var secondTree = myPlants[1].list[1];
+const secondTree = myPlants[1].list[1];
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md
index e790e3eabd2..b8ef650adfb 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md
@@ -14,7 +14,7 @@ dashedName: accessing-nested-objects
 这是一个嵌套对象：
 
 ```js
-var ourStorage = {
+const ourStorage = {
   "desk": {
     "drawer": "stapler"
   },
@@ -26,6 +26,7 @@ var ourStorage = {
     "bottom drawer": "soda"
   }
 };
+
 ourStorage.cabinet["top drawer"].folder2;
 ourStorage.desk.drawer;
 ```
@@ -66,7 +67,7 @@ assert(/=\s*myStorage\.car\.inside\[\s*("|')glove box\1\s*\]/g.test(code));
 ## --seed-contents--
 
 ```js
-var myStorage = {
+const myStorage = {
   "car": {
     "inside": {
       "glove box": "maps",
@@ -78,13 +79,13 @@ var myStorage = {
   }
 };
 
-var gloveBoxContents = undefined;
+const gloveBoxContents = undefined;
 ```
 
 # --solutions--
 
 ```js
-var myStorage = {
+const myStorage = {
   "car":{
     "inside":{
       "glove box":"maps",
@@ -95,5 +96,5 @@ var myStorage = {
     }
   }
 };
-var gloveBoxContents = myStorage.car.inside["glove box"];
+const gloveBoxContents = myStorage.car.inside["glove box"];
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md
index db056925700..043f2e84b29 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md
@@ -16,11 +16,12 @@ dashedName: accessing-object-properties-with-bracket-notation
 这是一个使用方括号表示法读取对象属性的例子：
 
 ```js
-var myObj = {
+const myObj = {
   "Space Name": "Kirk",
   "More Space": "Spock",
   "NoSpace": "USS Enterprise"
 };
+
 myObj["Space Name"];
 myObj['More Space'];
 myObj["NoSpace"];
@@ -78,26 +79,25 @@ assert(code.match(/testObj\s*?\[('|")[^'"]+\1\]/g).length > 1);
 
 ```js
 // Setup
-var testObj = {
+const testObj = {
   "an entree": "hamburger",
   "my side": "veggies",
   "the drink": "water"
 };
 
 // Only change code below this line
-
-var entreeValue = testObj;   // Change this line
-var drinkValue = testObj;    // Change this line
+const entreeValue = testObj;   // Change this line
+const drinkValue = testObj;    // Change this line
 ```
 
 # --solutions--
 
 ```js
-var testObj = {
+const testObj = {
   "an entree": "hamburger",
   "my side": "veggies",
   "the drink": "water"
 };
-var entreeValue = testObj["an entree"];
-var drinkValue = testObj['the drink'];
+const entreeValue = testObj["an entree"];
+const drinkValue = testObj['the drink'];
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md
index d5663a178bb..f422d74a7ea 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md
@@ -16,15 +16,17 @@ dashedName: accessing-object-properties-with-dot-notation
 这里是一个用点符号（`.`）读取对象属性的示例：
 
 ```js
-var myObj = {
+const myObj = {
   prop1: "val1",
   prop2: "val2"
 };
-var prop1val = myObj.prop1;
-var prop2val = myObj.prop2;
+
+const prop1val = myObj.prop1;
+const prop2val = myObj.prop2;
 ```
 
 `prop1val` 的值将为字符串 `val1`，并且`prop2val` 的值将为字符串 `val2`。
+
 # --instructions--
 
 使用点号读取 `testObj` 的属性值。 将变量 `hatValue` 的值设置为该对象的 `hat` 属性的值，并将变量 `shirtValue` 的值设置为该对象的 `shirt` 属性的值。
@@ -73,27 +75,26 @@ assert(code.match(/testObj\.\w+/g).length > 1);
 
 ```js
 // Setup
-var testObj = {
+const testObj = {
   "hat": "ballcap",
   "shirt": "jersey",
   "shoes": "cleats"
 };
 
 // Only change code below this line
-
-var hatValue = testObj;      // Change this line
-var shirtValue = testObj;    // Change this line
+const hatValue = testObj;      // Change this line
+const shirtValue = testObj;    // Change this line
 ```
 
 # --solutions--
 
 ```js
-var testObj = {
+const testObj = {
   "hat": "ballcap",
   "shirt": "jersey",
   "shoes": "cleats"
 };
 
-var hatValue = testObj.hat;
-var shirtValue = testObj.shirt;
+const hatValue = testObj.hat;
+const shirtValue = testObj.shirt;
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md
index 728d5170acf..229bb209627 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md
@@ -14,11 +14,14 @@ dashedName: accessing-object-properties-with-variables
 以下是一个使用变量来访问属性的例子：
 
 ```js
-var dogs = {
-  Fido: "Mutt",  Hunter: "Doberman",  Snoopie: "Beagle"
+const dogs = {
+  Fido: "Mutt",
+  Hunter: "Doberman",
+  Snoopie: "Beagle"
 };
-var myDog = "Hunter";
-var myBreed = dogs[myDog];
+
+const myDog = "Hunter";
+const myBreed = dogs[myDog];
 console.log(myBreed);
 ```
 
@@ -27,14 +30,16 @@ console.log(myBreed);
 使用这一概念的另一种情况是：属性的名字是在程序运行期间动态收集得到的。如下所示：
 
 ```js
-var someObj = {
+const someObj = {
   propName: "John"
 };
+
 function propPrefix(str) {
-  var s = "prop";
+  const s = "prop";
   return s + str;
 }
-var someProp = propPrefix("Name");
+
+const someProp = propPrefix("Name");
 console.log(someObj[someProp]);
 ```
 
@@ -96,26 +101,25 @@ if(typeof player !== "undefined"){(function(v){return v;})(player);}
 
 ```js
 // Setup
-var testObj = {
+const testObj = {
   12: "Namath",
   16: "Montana",
   19: "Unitas"
 };
 
 // Only change code below this line
-
-var playerNumber;       // Change this line
-var player = testObj;   // Change this line
+const playerNumber = 42;  // Change this line
+const player = testObj;   // Change this line
 ```
 
 # --solutions--
 
 ```js
-var testObj = {
+const testObj = {
   12: "Namath",
   16: "Montana",
   19: "Unitas"
 };
-var playerNumber = 16;
-var player = testObj[playerNumber];
+const playerNumber = 16;
+const player = testObj[playerNumber];
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md
index 8657efc29d4..1cb9728b5d1 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md
@@ -28,7 +28,7 @@ ourDog["bark"] = "bow-wow";
 例如：
 
 ```js
-var ourDog = {
+const ourDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
@@ -67,7 +67,7 @@ assert(!/bark[^\n]:/.test(code));
 ## --seed-contents--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
@@ -80,7 +80,7 @@ var myDog = {
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md
index af90b540236..b8e5d7b0b33 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md
@@ -18,7 +18,7 @@ JavaScript 中，我们通过符号 `+` 来进行加法运算。
 **代码示例:**
 
 ```js
-myVar = 5 + 10;
+const myVar = 5 + 10;
 ```
 
 现在，变量 `myVar` 的值为 `15`。
@@ -52,11 +52,11 @@ assert(/\+/.test(code));
 ## --seed-contents--
 
 ```js
-var sum = 10 + 0;
+const sum = 10 + 0;
 ```
 
 # --solutions--
 
 ```js
-var sum = 10 + 10;
+const sum = 10 + 10;
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md
index 98dba35fbd5..565dd14f8a5 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md
@@ -92,7 +92,7 @@ assert(code.match(/break/g).length > 2);
 
 ```js
 function switchOfStuff(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
 
@@ -108,7 +108,7 @@ switchOfStuff(1);
 
 ```js
 function switchOfStuff(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case "a":
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md
index 0795af9b468..9d668d14f88 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md
@@ -14,8 +14,8 @@ dashedName: appending-variables-to-strings
 示例：
 
 ```js
-var anAdjective = "awesome!";
-var ourStr = "freeCodeCamp is ";
+const anAdjective = "awesome!";
+let ourStr = "freeCodeCamp is ";
 ourStr += anAdjective;
 ```
 
@@ -64,15 +64,14 @@ assert(code.match(/myStr\s*\+=\s*someAdjective\s*/).length > 0);
 
 ```js
 // Change code below this line
-
-var someAdjective;
-var myStr = "Learning to code is ";
+const someAdjective = "";
+let myStr = "Learning to code is ";
 ```
 
 # --solutions--
 
 ```js
-var someAdjective = "neat";
-var myStr = "Learning to code is ";
+const someAdjective = "neat";
+let myStr = "Learning to code is ";
 myStr += someAdjective;
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md
index f918c4e796e..09243281509 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md
@@ -18,7 +18,7 @@ dashedName: build-javascript-objects
 这里是一个猫对象的样本：
 
 ```js
-var cat = {
+const cat = {
   "name": "Whiskers",
   "legs": 4,
   "tails": 1,
@@ -29,7 +29,7 @@ var cat = {
 在此示例中，所有属性都存储为字符串，例如 `name`、`legs` 和 `tails`。 然而，你也可以使用数字作为属性。 你甚至可以省略单字字符串属性中的引号，如下所示：
 
 ```js
-var anotherObject = {
+const anotherObject = {
   make: "Ford",
   5: "five",
   "model": "focus"
@@ -139,18 +139,18 @@ assert(
 ## --seed-contents--
 
 ```js
-var myDog = {
-// Only change code below this line
+const myDog = {
+  // Only change code below this line
 
 
-// Only change code above this line
+  // Only change code above this line
 };
 ```
 
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md
index 8e15f96ca2c..2d3e0f6c31e 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md
@@ -16,7 +16,7 @@ dashedName: comparison-with-the-equality-operator
 ```js
 function equalityTest(myVal) {
   if (myVal == 10) {
-     return "Equal";
+    return "Equal";
   }
   return "Not Equal";
 }
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md
index ba6834c0a08..fcf67346694 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md
@@ -20,7 +20,7 @@ myVar = myVar + 5;
 其中一种就是 `+=` 运算符。
 
 ```js
-var myVar = 1;
+let myVar = 1;
 myVar += 5;
 console.log(myVar);
 ```
@@ -61,9 +61,9 @@ assert(code.match(/\+=/g).length === 3);
 
 ```js
 assert(
-  /var a = 3;/.test(code) &&
-    /var b = 17;/.test(code) &&
-    /var c = 12;/.test(code)
+  /let a = 3;/.test(code) &&
+    /let b = 17;/.test(code) &&
+    /let c = 12;/.test(code)
 );
 ```
 
@@ -78,9 +78,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 3;
-var b = 17;
-var c = 12;
+let a = 3;
+let b = 17;
+let c = 12;
 
 // Only change code below this line
 a = a + 12;
@@ -91,9 +91,9 @@ c = c + 7;
 # --solutions--
 
 ```js
-var a = 3;
-var b = 17;
-var c = 12;
+let a = 3;
+let b = 17;
+let c = 12;
 
 a += 12;
 b += 9;
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md
index c84fb70b713..4d79833dcdc 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md
@@ -55,9 +55,9 @@ assert(code.match(/\/=/g).length === 3);
 
 ```js
 assert(
-  /var a = 48;/.test(code) &&
-    /var b = 108;/.test(code) &&
-    /var c = 33;/.test(code)
+  /let a = 48;/.test(code) &&
+    /let b = 108;/.test(code) &&
+    /let c = 33;/.test(code)
 );
 ```
 
@@ -72,9 +72,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 48;
-var b = 108;
-var c = 33;
+let a = 48;
+let b = 108;
+let c = 33;
 
 // Only change code below this line
 a = a / 12;
@@ -85,9 +85,9 @@ c = c / 11;
 # --solutions--
 
 ```js
-var a = 48;
-var b = 108;
-var c = 33;
+let a = 48;
+let b = 108;
+let c = 33;
 
 a /= 12;
 b /= 4;
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md
index 38415e0189d..96165f198ec 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md
@@ -55,9 +55,9 @@ assert(code.match(/\*=/g).length === 3);
 
 ```js
 assert(
-  /var a = 5;/.test(code) &&
-    /var b = 12;/.test(code) &&
-    /var c = 4\.6;/.test(code)
+  /let a = 5;/.test(code) &&
+    /let b = 12;/.test(code) &&
+    /let c = 4\.6;/.test(code)
 );
 ```
 
@@ -72,9 +72,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 5;
-var b = 12;
-var c = 4.6;
+let a = 5;
+let b = 12;
+let c = 4.6;
 
 // Only change code below this line
 a = a * 5;
@@ -85,9 +85,9 @@ c = c * 10;
 # --solutions--
 
 ```js
-var a = 5;
-var b = 12;
-var c = 4.6;
+let a = 5;
+let b = 12;
+let c = 4.6;
 
 a *= 5;
 b *= 3;
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md
index b80f278e2f6..79ab231e713 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md
@@ -55,7 +55,7 @@ assert(code.match(/-=/g).length === 3);
 
 ```js
 assert(
-  /var a = 11;/.test(code) && /var b = 9;/.test(code) && /var c = 3;/.test(code)
+  /let a = 11;/.test(code) && /let b = 9;/.test(code) && /let c = 3;/.test(code)
 );
 ```
 
@@ -70,9 +70,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 11;
-var b = 9;
-var c = 3;
+let a = 11;
+let b = 9;
+let c = 3;
 
 // Only change code below this line
 a = a - 6;
@@ -83,9 +83,9 @@ c = c - 1;
 # --solutions--
 
 ```js
-var a = 11;
-var b = 9;
-var c = 3;
+let a = 11;
+let b = 9;
+let c = 3;
 
 a -= 6;
 b -= 15;
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md
index c5bdd608daf..72e538fae15 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md
@@ -16,7 +16,7 @@ dashedName: concatenating-strings-with-the-plus-equals-operator
 例如：
 
 ```js
-var ourStr = "I come first. ";
+let ourStr = "I come first. ";
 ourStr += "I come second.";
 ```
 
@@ -57,14 +57,12 @@ assert(code.match(/myStr\s*\+=\s*(["']).*\1/g));
 ## --seed-contents--
 
 ```js
-// Only change code below this line
-
-var myStr;
+let myStr;
 ```
 
 # --solutions--
 
 ```js
-var myStr = "This is the first sentence. ";
+let myStr = "This is the first sentence. ";
 myStr += "This is the second sentence.";
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md
index 9c637cd5f3a..1376c034709 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md
@@ -14,8 +14,8 @@ dashedName: constructing-strings-with-variables
 例如：
 
 ```js
-var ourName = "freeCodeCamp";
-var ourStr = "Hello, our name is " + ourName + ", how are you?";
+const ourName = "freeCodeCamp";
+const ourStr = "Hello, our name is " + ourName + ", how are you?";
 ```
 
 `ourStr` 值为 `Hello, our name is freeCodeCamp, how are you?`
@@ -63,13 +63,13 @@ assert(code.match(/["']\s*\+\s*myName\s*\+\s*["']/g).length > 0);
 
 ```js
 // Only change code below this line
-var myName;
-var myStr;
+const myName = "";
+const myStr = "";
 ```
 
 # --solutions--
 
 ```js
-var myName = "Bob";
-var myStr = "My name is " + myName + " and I am well!";
+const myName = "Bob";
+const myStr = "My name is " + myName + " and I am well!";
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md
index 73674c06cf0..2b10dc45001 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md
@@ -159,7 +159,7 @@ assert(
 ## --seed-contents--
 
 ```js
-var count = 0;
+let count = 0;
 
 function cc(card) {
   // Only change code below this line
@@ -175,7 +175,7 @@ cc(2); cc(3); cc(7); cc('K'); cc('A');
 # --solutions--
 
 ```js
-var count = 0;
+let count = 0;
 function cc(card) {
   switch(card) {
     case 2:
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md
index 147dbfea17c..f4a2fd37a75 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md
@@ -42,13 +42,14 @@ assert(myDecimal % 1 != 0);
 ## --seed-contents--
 
 ```js
-var ourDecimal = 5.7;
+const ourDecimal = 5.7;
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myDecimal = 9.9;
+const myDecimal = 9.9;
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md
index 8d431c91cca..6bb66dfee2c 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md
@@ -39,7 +39,7 @@ assert(myVar === 10);
 
 ```js
 assert(
-  /var\s*myVar\s*=\s*11;\s*\/*.*\s*([-]{2}\s*myVar|myVar\s*[-]{2});/.test(code)
+  /let\s*myVar\s*=\s*11;\s*\/*.*\s*([-]{2}\s*myVar|myVar\s*[-]{2});/.test(code)
 );
 ```
 
@@ -52,7 +52,7 @@ assert(/[-]{2}\s*myVar|myVar\s*[-]{2}/.test(code));
 不应修改注释上方的代码。
 
 ```js
-assert(/var myVar = 11;/.test(code));
+assert(/let myVar = 11;/.test(code));
 ```
 
 # --seed--
@@ -66,7 +66,7 @@ assert(/var myVar = 11;/.test(code));
 ## --seed-contents--
 
 ```js
-var myVar = 11;
+let myVar = 11;
 
 // Only change code below this line
 myVar = myVar - 1;
@@ -75,6 +75,6 @@ myVar = myVar - 1;
 # --solutions--
 
 ```js
-var myVar = 11;
+let myVar = 11;
 myVar--;
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md
index ca4daac292e..097db448dc3 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md
@@ -18,7 +18,7 @@ delete ourDog.bark;
 例如：
 
 ```js
-var ourDog = {
+const ourDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
@@ -70,7 +70,7 @@ assert(code.match(/"tails": 1/g).length > 0);
 
 ```js
 // Setup
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
@@ -79,12 +79,13 @@ var myDog = {
 };
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md
index ded89b1d474..f52d89019ed 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md
@@ -46,11 +46,11 @@ assert(code.match(/quotient/g).length === 1);
 ## --seed-contents--
 
 ```js
-var quotient = 0.0 / 2.0; // Change this line
+const quotient = 0.0 / 2.0; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var quotient = 4.4 / 2.0;
+const quotient = 4.4 / 2.0;
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md
index ac7f5188116..b2700333de1 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md
@@ -16,7 +16,7 @@ JavaScript 中使用 `/` 符号做除法运算。
 **示例**
 
 ```js
-myVar = 16 / 2;
+const myVar = 16 / 2;
 ```
 
 现在，变量 `myVar` 的值为 `8`。
@@ -49,11 +49,11 @@ assert(/\d+\s*\/\s*\d+/.test(code));
 ## --seed-contents--
 
 ```js
-var quotient = 66 / 0;
+const quotient = 66 / 0;
 ```
 
 # --solutions--
 
 ```js
-var quotient = 66 / 33;
+const quotient = 66 / 33;
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md
index 5bfba8d62a4..0a19489a0b8 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md
@@ -89,11 +89,11 @@ console.log('myStr:\n' + myStr);}})();
 ## --seed-contents--
 
 ```js
-var myStr; // Change this line
+const myStr = ""; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var myStr = "FirstLine\n\t\\SecondLine\nThirdLine";
+const myStr = "FirstLine\n\t\\SecondLine\nThirdLine";
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md
index a7791d0a9ab..12d0718e335 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md
@@ -14,7 +14,7 @@ dashedName: escaping-literal-quotes-in-strings
 在 JavaScript 中，可以通过在引号前面使用<dfn>反斜杠</dfn>（`\`）来<dfn>转义</dfn>引号。
 
 ```js
-var sampleStr = "Alan said, \"Peter is learning JavaScript\".";
+const sampleStr = "Alan said, \"Peter is learning JavaScript\".";
 ```
 
 有了转义符号，JavaScript 就知道这个单引号或双引号并不是字符串的结尾，而是字符串内的字符。 所以，上面的字符串打印到控制台的结果为：
@@ -62,11 +62,11 @@ assert(/I am a "double quoted" string inside "double quotes(\."|"\.)$/.test(mySt
 ## --seed-contents--
 
 ```js
-var myStr = ""; // Change this line
+const myStr = ""; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var myStr = "I am a \"double quoted\" string inside \"double quotes\".";
+const myStr = "I am a \"double quoted\" string inside \"double quotes\".";
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md
index 4d7a9b7e341..53da52ae6f5 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md
@@ -31,7 +31,7 @@ dashedName: finding-a-remainder-in-javascript
 变量 `remainder` 应该被初始化。
 
 ```js
-assert(/var\s+?remainder/.test(code));
+assert(/(const|let|var)\s+?remainder/.test(code));
 ```
 
 `remainder` 的值应该等于 `2`。
@@ -57,13 +57,11 @@ assert(/\s+?remainder\s*?=\s*?.*%.*;?/.test(code));
 ## --seed-contents--
 
 ```js
-// Only change code below this line
-
-var remainder;
+const remainder = 0;
 ```
 
 # --solutions--
 
 ```js
-var remainder =  11 % 3;
+const remainder = 11 % 3;
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md
index c25271e30ec..01af4403ed2 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md
@@ -14,9 +14,10 @@ dashedName: global-vs--local-scope-in-functions
 下面为例：
 
 ```js
-var someVar = "Hat";
+const someVar = "Hat";
+
 function myFun() {
-  var someVar = "Head";
+  const someVar = "Head";
   return someVar;
 }
 ```
@@ -53,13 +54,11 @@ assert(/return outerWear/.test(code));
 
 ```js
 // Setup
-var outerWear = "T-Shirt";
+const outerWear = "T-Shirt";
 
 function myOutfit() {
   // Only change code below this line
 
-
-
   // Only change code above this line
   return outerWear;
 }
@@ -70,9 +69,9 @@ myOutfit();
 # --solutions--
 
 ```js
-var outerWear = "T-Shirt";
+const outerWear = "T-Shirt";
 function myOutfit() {
-  var outerWear = "sweater";
+  const outerWear = "sweater";
   return outerWear;
 }
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md
index a0a37a2ad49..ad741ccb52a 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md
@@ -90,7 +90,8 @@ assert(golfScore(5, 9) === 'Go Home!');
 ## --seed-contents--
 
 ```js
-var names = ["Hole-in-one!", "Eagle", "Birdie", "Par", "Bogey", "Double Bogey", "Go Home!"];
+const names = ["Hole-in-one!", "Eagle", "Birdie", "Par", "Bogey", "Double Bogey", "Go Home!"];
+
 function golfScore(par, strokes) {
   // Only change code below this line
 
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md
index 6dd41ca4060..0012e0526aa 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md
@@ -39,7 +39,7 @@ assert(myVar === 88);
 
 ```js
 assert(
-  /var\s*myVar\s*=\s*87;\s*\/*.*\s*([+]{2}\s*myVar|myVar\s*[+]{2});/.test(code)
+  /let\s*myVar\s*=\s*87;\s*\/*.*\s*([+]{2}\s*myVar|myVar\s*[+]{2});/.test(code)
 );
 ```
 
@@ -52,7 +52,7 @@ assert(/[+]{2}\s*myVar|myVar\s*[+]{2}/.test(code));
 不应该修改注释上面的代码。
 
 ```js
-assert(/var myVar = 87;/.test(code));
+assert(/let myVar = 87;/.test(code));
 ```
 
 # --seed--
@@ -66,7 +66,7 @@ assert(/var myVar = 87;/.test(code));
 ## --seed-contents--
 
 ```js
-var myVar = 87;
+let myVar = 87;
 
 // Only change code below this line
 myVar = myVar + 1;
@@ -75,6 +75,6 @@ myVar = myVar + 1;
 # --solutions--
 
 ```js
-var myVar = 87;
+let myVar = 87;
 myVar++;
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md
index 3d2d90e45c6..db610a9cfff 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md
@@ -64,7 +64,7 @@ assert(testElse(10) === 'Bigger than 5');
 不要修改相应注释的上面或下面的代码。
 
 ```js
-assert(/var result = "";/.test(code) && /return result;/.test(code));
+assert(/let result = "";/.test(code) && /return result;/.test(code));
 ```
 
 # --seed--
@@ -73,7 +73,7 @@ assert(/var result = "";/.test(code) && /return result;/.test(code));
 
 ```js
 function testElse(val) {
-  var result = "";
+  let result = "";
   // Only change code below this line
 
   if (val > 5) {
@@ -95,7 +95,7 @@ testElse(4);
 
 ```js
 function testElse(val) {
-  var result = "";
+  let result = "";
   if(val > 5) {
     result = "Bigger than 5";
   } else {
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md
index 335f7fcdf3b..f01f2b48eaa 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md
@@ -12,8 +12,9 @@ dashedName: iterate-through-an-array-with-a-for-loop
 JavaScript 中的一个常见任务是遍历数组的内容。 一种方法是使用 `for` 循环。 下面的代码将输出数组 `arr` 的每个元素到控制台：
 
 ```js
-var arr = [10, 9, 8, 7, 6];
-for (var i = 0; i < arr.length; i++) {
+const arr = [10, 9, 8, 7, 6];
+
+for (let i = 0; i < arr.length; i++) {
    console.log(arr[i]);
 }
 ```
@@ -62,18 +63,19 @@ assert(!__helpers.removeWhiteSpace(code).match(/total[=+-]0*[1-9]+/gm));
 
 ```js
 // Setup
-var myArr = [ 2, 3, 4, 5, 6];
+const myArr = [2, 3, 4, 5, 6];
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myArr = [ 2, 3, 4, 5, 6];
-var total = 0;
+const myArr = [2, 3, 4, 5, 6];
+let total = 0;
 
-for (var i = 0; i < myArr.length; i++) {
+for (let i = 0; i < myArr.length; i++) {
   total += myArr[i];
 }
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md
index 725a66d7151..338de200474 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md
@@ -12,8 +12,9 @@ dashedName: iterate-with-javascript-do---while-loops
 下一种循环叫作 `do...while` 循环。 它被称为 `do...while` 循环，是因为不论什么情况，它都会首先 `do`（运行）循环里的第一部分代码，然后 `while`（当）规定的条件被评估为 `true`（真）的时候，它会继续运行循环。
 
 ```js
-var ourArray = [];
-var i = 0;
+const ourArray = [];
+let i = 0;
+
 do {
   ourArray.push(i);
   i++;
@@ -23,8 +24,9 @@ do {
 上面的示例行为类似于其他类型的循环，由此产生的数组将看起来像 `[0, 1, 2, 3, 4]`。 然而，`do...while` 不同于其他循环的地方，是第一次循环检查失败时的行为。 让我们看看代码中的区别：这里是一个常规的 `while` 循环，只要 `i < 5`，就会在循环中运行代码：
 
 ```js
-var ourArray = []; 
-var i = 5;
+const ourArray = []; 
+let i = 5;
+
 while (i < 5) {
   ourArray.push(i);
   i++;
@@ -34,8 +36,9 @@ while (i < 5) {
 这个例子中，定义了一个空数组 `ourArray` 以及一个值为 5 的 `i` 。 当执行 `while` 循环时，因为 `i` 不小于 5，所以循环条件为 `false`，循环内的代码将不会执行。 `ourArray` 最终没有添加任何内容，因此示例中的所有代码执行完时，ourArray 仍然是`[]`。 现在，看一下 `do...while` 循环。
 
 ```js
-var ourArray = []; 
-var i = 5;
+const ourArray = []; 
+let i = 5;
+
 do {
   ourArray.push(i);
   i++;
@@ -80,8 +83,8 @@ if(typeof myArray !== "undefined"){(function(){return myArray;})();}
 
 ```js
 // Setup
-var myArray = [];
-var i = 10;
+const myArray = [];
+let i = 10;
 
 // Only change code below this line
 while (i < 5) {
@@ -93,8 +96,8 @@ while (i < 5) {
 # --solutions--
 
 ```js
-var myArray = [];
-var i = 10;
+const myArray = [];
+let i = 10;
 do {
   myArray.push(i);
   i++;
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md
index 60caa1a3e77..2c950d2134f 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md
@@ -15,9 +15,10 @@ dashedName: local-scope-and-functions
 
 ```js
 function myTest() {
-  var loc = "foo";
+  const loc = "foo";
   console.log(loc);
 }
+
 myTest();
 console.log(loc);
 ```
@@ -38,6 +39,7 @@ console.log(loc);
 function declared() {
   myVar;
 }
+
 assert.throws(declared, ReferenceError);
 ```
 
@@ -57,7 +59,6 @@ assert(
 
 ```js
 function myLocalScope() {
-
   // Only change code below this line
 
   console.log('inside myLocalScope', myVar);
@@ -73,9 +74,8 @@ console.log('outside myLocalScope', myVar);
 
 ```js
 function myLocalScope() {
-
   // Only change code below this line
-  var myVar;
+  let myVar;
   console.log('inside myLocalScope', myVar);
 }
 myLocalScope();
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md
index 340f78cebb0..4e95ec67e78 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md
@@ -16,10 +16,10 @@ dashedName: manipulate-arrays-with-push
 示例：
 
 ```js
-var arr1 = [1,2,3];
+const arr1 = [1, 2, 3];
 arr1.push(4);
 
-var arr2 = ["Stimpson", "J", "cat"];
+const arr2 = ["Stimpson", "J", "cat"];
 arr2.push(["happy", "joy"]);
 ```
 
@@ -64,14 +64,15 @@ assert(
 
 ```js
 // Setup
-var myArray = [["John", 23], ["cat", 2]];
+const myArray = [["John", 23], ["cat", 2]];
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myArray = [["John", 23], ["cat", 2]];
+const myArray = [["John", 23], ["cat", 2]];
 myArray.push(["dog",3]);
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md
index 64f2075f392..d2145515b93 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md
@@ -14,7 +14,7 @@ dashedName: manipulating-complex-objects
 这是一个复杂数据结构的示例：
 
 ```js
-var ourMusic = [
+const ourMusic = [
   {
     "artist": "Daft Punk",
     "title": "Homework",
@@ -135,7 +135,7 @@ myMusic.forEach(object => {
 ## --seed-contents--
 
 ```js
-var myMusic = [
+const myMusic = [
   {
     "artist": "Billy Joel",
     "title": "Piano Man",
@@ -153,7 +153,7 @@ var myMusic = [
 # --solutions--
 
 ```js
-var myMusic = [
+const myMusic = [
   {
     "artist": "Billy Joel",
     "title": "Piano Man",
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md
index 0c0b63f9c15..dfe62e3d652 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md
@@ -12,7 +12,7 @@ dashedName: multiple-identical-options-in-switch-statements
 如果你忘了给 `switch` 的每一条 `case` 添加 `break`，那么后续的 `case` 会一直执行，直到遇见 `break` 为止。 如果你想为 `switch` 中的多个不同的输入设置相同的结果，可以这样写：
 
 ```js
-var result = "";
+let result = "";
 switch(val) {
   case 1:
   case 2:
@@ -109,7 +109,7 @@ assert(code.match(/case/g).length === 9);
 
 ```js
 function sequentialSizes(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
 
@@ -125,7 +125,7 @@ sequentialSizes(1);
 
 ```js
 function sequentialSizes(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case 1:
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md
index 31e2ba9e964..a1f6eb7d959 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md
@@ -42,11 +42,11 @@ assert(/\*/.test(code));
 ## --seed-contents--
 
 ```js
-var product = 2.0 * 0.0;
+const product = 2.0 * 0.0;
 ```
 
 # --solutions--
 
 ```js
-var product = 2.0 * 2.5;
+const product = 2.0 * 2.5;
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md
index 458a8b9294f..eff8e132266 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md
@@ -16,7 +16,7 @@ JavaScript 使用 `*` 符号表示两数相乘。
 **示例**
 
 ```js
-myVar = 13 * 13;
+const myVar = 13 * 13;
 ```
 
 现在，变量 `myVar` 的值为 `169`。
@@ -50,11 +50,11 @@ assert(/\*/.test(code));
 ## --seed-contents--
 
 ```js
-var product = 8 * 0;
+const product = 8 * 0;
 ```
 
 # --solutions--
 
 ```js
-var product = 8 * 10;
+const product = 8 * 10;
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md
index ac3f1b0fb7b..89d74fdd30e 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md
@@ -12,7 +12,7 @@ dashedName: nest-one-array-within-another-array
 您也可以在其他数组中嵌套数组，如：
 
 ```js
-[["Bulls", 23], ["White Sox", 45]]
+const teams = [["Bulls", 23], ["White Sox", 45]];
 ```
 
 这也叫做多维数组（<dfn>multi-dimensional array</dfn>）。
@@ -41,11 +41,11 @@ if(typeof myArray !== "undefined"){(function(){return myArray;})();}
 
 ```js
 // Only change code below this line
-var myArray = [];
+const myArray = [];
 ```
 
 # --solutions--
 
 ```js
-var myArray = [[1,2,3]];
+const myArray = [[1, 2, 3]];
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md
index 98521e0599f..d1018d60eb1 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md
@@ -68,34 +68,33 @@ assert(lookUpProfile('Akira', 'address') === 'No such property');
 
 ```js
 // Setup
-var contacts = [
-    {
-        "firstName": "Akira",
-        "lastName": "Laine",
-        "number": "0543236543",
-        "likes": ["Pizza", "Coding", "Brownie Points"]
-    },
-    {
-        "firstName": "Harry",
-        "lastName": "Potter",
-        "number": "0994372684",
-        "likes": ["Hogwarts", "Magic", "Hagrid"]
-    },
-    {
-        "firstName": "Sherlock",
-        "lastName": "Holmes",
-        "number": "0487345643",
-        "likes": ["Intriguing Cases", "Violin"]
-    },
-    {
-        "firstName": "Kristian",
-        "lastName": "Vos",
-        "number": "unknown",
-        "likes": ["JavaScript", "Gaming", "Foxes"]
-    }
+const contacts = [
+  {
+    firstName: "Akira",
+    lastName: "Laine",
+    number: "0543236543",
+    likes: ["Pizza", "Coding", "Brownie Points"],
+  },
+  {
+    firstName: "Harry",
+    lastName: "Potter",
+    number: "0994372684",
+    likes: ["Hogwarts", "Magic", "Hagrid"],
+  },
+  {
+    firstName: "Sherlock",
+    lastName: "Holmes",
+    number: "0487345643",
+    likes: ["Intriguing Cases", "Violin"],
+  },
+  {
+    firstName: "Kristian",
+    lastName: "Vos",
+    number: "unknown",
+    likes: ["JavaScript", "Gaming", "Foxes"],
+  },
 ];
 
-
 function lookUpProfile(name, prop) {
   // Only change code below this line
 
@@ -108,44 +107,38 @@ lookUpProfile("Akira", "likes");
 # --solutions--
 
 ```js
-var contacts = [
-    {
-        "firstName": "Akira",
-        "lastName": "Laine",
-        "number": "0543236543",
-        "likes": ["Pizza", "Coding", "Brownie Points"]
-    },
-    {
-        "firstName": "Harry",
-        "lastName": "Potter",
-        "number": "0994372684",
-        "likes": ["Hogwarts", "Magic", "Hagrid"]
-    },
-    {
-        "firstName": "Sherlock",
-        "lastName": "Holmes",
-        "number": "0487345643",
-        "likes": ["Intriguing Cases", "Violin"]
-    },
-    {
-        "firstName": "Kristian",
-        "lastName": "Vos",
-        "number": "unknown",
-        "likes": ["JavaScript", "Gaming", "Foxes"]
-    },
+const contacts = [
+  {
+    firstName: "Akira",
+    lastName: "Laine",
+    number: "0543236543",
+    likes: ["Pizza", "Coding", "Brownie Points"],
+  },
+  {
+    firstName: "Harry",
+    lastName: "Potter",
+    number: "0994372684",
+    likes: ["Hogwarts", "Magic", "Hagrid"],
+  },
+  {
+    firstName: "Sherlock",
+    lastName: "Holmes",
+    number: "0487345643",
+    likes: ["Intriguing Cases", "Violin"],
+  },
+  {
+    firstName: "Kristian",
+    lastName: "Vos",
+    number: "unknown",
+    likes: ["JavaScript", "Gaming", "Foxes"],
+  },
 ];
-
-
-//Write your function in between these comments
-function lookUpProfile(name, prop){
-    for(var i in contacts){
-      if(contacts[i].firstName === name) {
-        return contacts[i][prop] || "No such property";
-      }
+function lookUpProfile(name, prop) {
+  for (let i in contacts) {
+    if (contacts[i].firstName === name) {
+      return contacts[i][prop] || "No such property";
     }
-   return "No such contact";
+  }
+  return "No such contact";
 }
-//Write your function in between these comments
-
-lookUpProfile("Akira", "likes");
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md
index 8d70d9c8bd5..255b74213c8 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md
@@ -12,21 +12,21 @@ dashedName: quoting-strings-with-single-quotes
 JavaScript 中的<dfn>字符串</dfn>可以使用开始和结束都是同类型的单引号或双引号表示。 与其他一些编程语言不同的是，单引号和双引号的功能在 JavaScript 中是相同的。
 
 ```js
-doubleQuoteStr = "This is a string"; 
-singleQuoteStr = 'This is also a string';
+const doubleQuoteStr = "This is a string"; 
+const singleQuoteStr = 'This is also a string';
 ```
 
 当你需要在一个字符串中使用多个引号的时候，你可以使用单引号包裹双引号或者相反。 常见的场景比如在字符串中包含对话的句子需要用引号包裹。 另外比如在一个包含有 `<a>` 标签的字符串中，标签的属性值需要用引号包裹。
 
 ```js
-conversation = 'Finn exclaims to Jake, "Algebraic!"';
+const conversation = 'Finn exclaims to Jake, "Algebraic!"';
 ```
 
 然而，如果你需要在其中使用外面的引号，这就成为一个问题。 记住，一个字符串在开头和结尾处有相同的引号。 要知道，字符串在开头和结尾都有相同的引号，如果在中间使用了相同的引号，字符串会提前中止并抛出错误。
 
 ```js
-goodStr = 'Jake asks Finn, "Hey, let\'s go on an adventure?"'; 
-badStr = 'Finn responds, "Let's go!"';
+const goodStr = 'Jake asks Finn, "Hey, let\'s go on an adventure?"'; 
+const badStr = 'Finn responds, "Let's go!"';
 ```
 
 在这里 `badStr` 会产生一个错误。
@@ -71,11 +71,11 @@ assert(code.match(/"/g).length === 4 && code.match(/'/g).length === 2);
 ## --seed-contents--
 
 ```js
-var myStr = "<a href=\"http://www.example.com\" target=\"_blank\">Link</a>";
+const myStr = "<a href=\"http://www.example.com\" target=\"_blank\">Link</a>";
 ```
 
 # --solutions--
 
 ```js
-var myStr = '<a href="http://www.example.com" target="_blank">Link</a>';
+const myStr = '<a href="http://www.example.com" target="_blank">Link</a>';
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md
index fc3d65d36df..053a7cbc6d1 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md
@@ -115,7 +115,7 @@ const _recordCollection = {
 
 ```js
 // Setup
-var recordCollection = {
+const recordCollection = {
   2548: {
     albumTitle: 'Slippery When Wet',
     artist: 'Bon Jovi',
@@ -146,7 +146,7 @@ updateRecords(recordCollection, 5439, 'artist', 'ABBA');
 # --solutions--
 
 ```js
-var recordCollection = {
+const recordCollection = {
   2548: {
     albumTitle: 'Slippery When Wet',
     artist: 'Bon Jovi',
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md
index c390f0231c5..141e5c20002 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md
@@ -14,9 +14,9 @@ dashedName: replace-loops-using-recursion
 
 ```js
   function multiply(arr, n) {
-    var product = 1;
-    for (var i = 0; i < n; i++) {
-        product *= arr[i];
+    let product = 1;
+    for (let i = 0; i < n; i++) {
+      product *= arr[i];
     }
     return product;
   }
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md
index 0325d50b498..0416c6010be 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md
@@ -108,7 +108,7 @@ assert(chainToSwitch(156) === '');
 
 ```js
 function chainToSwitch(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
   if (val === "bob") {
@@ -134,7 +134,7 @@ chainToSwitch(7);
 
 ```js
 function chainToSwitch(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case "bob":
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md
index fc2cec504e2..244198e630f 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md
@@ -17,7 +17,8 @@ dashedName: return-a-value-from-a-function-with-return
 function plusThree(num) {
   return num + 3;
 }
-var answer = plusThree(5);
+
+const answer = plusThree(5);
 ```
 
 `answer` 的值为 `8`。
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md
index 3120995b0b7..8d191929e48 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md
@@ -78,7 +78,7 @@ assert(code.match(/break/g).length > 2);
 
 ```js
 function caseInSwitch(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
 
@@ -94,7 +94,7 @@ caseInSwitch(1);
 
 ```js
 function caseInSwitch(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case 1:
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md
index 986e2352d7f..62071ef62c6 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md
@@ -81,13 +81,13 @@ var hasNumber = false;
 ## --seed-contents--
 
 ```js
-var myList = [];
+const myList = [];
 ```
 
 # --solutions--
 
 ```js
-var myList = [
+const myList = [
   ["Candy", 10],
   ["Potatoes", 12],
   ["Eggs", 12],
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md
index 545ee62d5eb..09cd58c72c8 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md
@@ -93,12 +93,10 @@ function nextInLine(arr, item) {
 
   return item;
   // Only change code above this line
-
-
 }
 
 // Setup
-var testArr = [1,2,3,4,5];
+const testArr = [1, 2, 3, 4, 5];
 
 // Display code
 console.log("Before: " + JSON.stringify(testArr));
@@ -109,7 +107,7 @@ console.log("After: " + JSON.stringify(testArr));
 # --solutions--
 
 ```js
-var testArr = [ 1,2,3,4,5];
+const testArr = [1, 2, 3, 4, 5];
 
 function nextInLine(arr, item) {
     arr.push(item);
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md
index 3dd333bf1d7..8f724a12dee 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md
@@ -14,7 +14,7 @@ dashedName: store-multiple-values-in-one-variable-using-javascript-arrays
 以左方括号开始定义一个数组，以右方括号结束，里面每个元素之间用逗号隔开，例如：
 
 ```js
-var sandwich = ["peanut butter", "jelly", "bread"]
+const sandwich = ["peanut butter", "jelly", "bread"];
 ```
 
 # --instructions--
@@ -53,11 +53,11 @@ assert(typeof myArray[1] !== 'undefined' && typeof myArray[1] == 'number');
 
 ```js
 // Only change code below this line
-var myArray = [];
+const myArray = [];
 ```
 
 # --solutions--
 
 ```js
-var myArray = ["The Answer", 42];
+const myArray = ["The Answer", 42];
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md
index ad7eaf40ac8..930fba699ec 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md
@@ -16,7 +16,7 @@ JavaScript 中使用 `-` 来做减法运算。
 **示例**
 
 ```js
-myVar = 12 - 6;
+const myVar = 12 - 6;
 ```
 
 现在，变量 `myVar` 的值为 `6`。
@@ -49,11 +49,11 @@ assert(/difference=45-33;?/.test(__helpers.removeWhiteSpace(code)));
 ## --seed-contents--
 
 ```js
-var difference = 45 - 0;
+const difference = 45 - 0;
 ```
 
 # --solutions--
 
 ```js
-var difference = 45 - 33;
+const difference = 45 - 33;
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md
index 509163d747a..9399256427b 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md
@@ -13,10 +13,11 @@ dashedName: testing-objects-for-properties
 **示例**
 
 ```js
-var myObj = {
+const myObj = {
   top: "hat",
   bottom: "pants"
 };
+
 myObj.hasOwnProperty("top");
 myObj.hasOwnProperty("middle");
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md
index c33001dd502..9693664fd12 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md
@@ -14,14 +14,14 @@ dashedName: understand-string-immutability
 例如，下面的代码：
 
 ```js
-var myStr = "Bob";
+let myStr = "Bob";
 myStr[0] = "J";
 ```
 
 是不会把变量 `myStr` 的值改变成 `Job` 的，因为变量 `myStr` 是不可变的。 注意，这*并不*意味着 `myStr` 永远不能被改变，只是字符串字面量 <dfn>string literal</dfn> 的各个字符不能被改变。 改变 `myStr` 的唯一方法是重新给它赋一个值，例如：
 
 ```js
-var myStr = "Bob";
+let myStr = "Bob";
 myStr = "Job";
 ```
 
@@ -55,7 +55,7 @@ assert(/myStr = "Jello World"/.test(code));
 
 ```js
 // Setup
-var myStr = "Jello World";
+let myStr = "Jello World";
 
 // Only change code below this line
 myStr[0] = "H"; // Change this line
@@ -65,6 +65,6 @@ myStr[0] = "H"; // Change this line
 # --solutions--
 
 ```js
-var myStr = "Jello World";
+let myStr = "Jello World";
 myStr = "Hello World";
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md
index 30fd5ce5314..10207efa5ca 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md
@@ -43,7 +43,6 @@ welcomeToBooleans();
 
 ```js
 function welcomeToBooleans() {
-
   // Only change code below this line
 
   return false; // Change this line
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md
index 550efd9bab4..9438d612dcd 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md
@@ -14,10 +14,12 @@ dashedName: understanding-undefined-value-returned-from-a-function
 **示例**
 
 ```js
-var sum = 0;
+let sum = 0;
+
 function addSum(num) {
   sum = sum + num;
 }
+
 addSum(3);
 ```
 
@@ -61,7 +63,7 @@ assert(
 
 ```js
 // Setup
-var sum = 0;
+let sum = 0;
 
 function addThree() {
   sum = sum + 3;
@@ -79,7 +81,7 @@ addFive();
 # --solutions--
 
 ```js
-var sum = 0;
+let sum = 0;
 
 function addThree() {
   sum = sum + 3;
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md
index 10d9d6b255c..696dadb9130 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md
@@ -14,7 +14,7 @@ dashedName: updating-object-properties
 举个例子，让我们看看 `ourDog`：
 
 ```js
-var ourDog = {
+const ourDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
@@ -54,7 +54,7 @@ assert(/"name": "Coder"/.test(code));
 
 ```js
 // Setup
-var myDog = {
+const myDog = {
   "name": "Coder",
   "legs": 4,
   "tails": 1,
@@ -62,12 +62,13 @@ var myDog = {
 };
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Coder",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md
index d5e2158e634..f7075609202 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md
@@ -16,8 +16,8 @@ dashedName: use-bracket-notation-to-find-the-nth-character-in-a-string
 例如：
 
 ```js
-var firstName = "Ada";
-var secondLetterOfFirstName = firstName[1];
+const firstName = "Ada";
+const secondLetterOfFirstName = firstName[1];
 ```
 
 `secondLetterOfFirstName` 值应该为字符串 `d`。
@@ -54,15 +54,15 @@ assert(code.match(/thirdLetterOfLastName\s*?=\s*?lastName\[.*?\]/));
 
 ```js
 // Setup
-var lastName = "Lovelace";
+const lastName = "Lovelace";
 
 // Only change code below this line
-var thirdLetterOfLastName = lastName; // Change this line
+const thirdLetterOfLastName = lastName; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var lastName = "Lovelace";
-var thirdLetterOfLastName = lastName[2];
+const lastName = "Lovelace";
+const thirdLetterOfLastName = lastName[2];
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md
index 0afaced6178..751c0bb7523 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md
@@ -73,7 +73,7 @@ function rangeOfNumbers(startNum, endNum) {
   if (endNum - startNum === 0) {
     return [startNum];
   } else {
-    var numbers = rangeOfNumbers(startNum, endNum - 1);
+    const numbers = rangeOfNumbers(startNum, endNum - 1);
     numbers.push(endNum);
     return numbers;
   }
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md
index 01b23f4bd45..d270f9f2a99 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md
@@ -20,7 +20,7 @@ parseInt(string, radix);
 这是一个示例：
 
 ```js
-var a = parseInt("11", 2);
+const a = parseInt("11", 2);
 ```
 
 变量 radix 表示 `11` 是在二进制系统中。 这个示例将字符串 `11` 转换为整数 `3`。
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md
index 26135ebac72..76acb0ca61b 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md
@@ -12,7 +12,7 @@ dashedName: use-the-parseint-function
 `parseInt()` 函数解析一个字符串返回一个整数。 下面是一个示例：
 
 ```js
-var a = parseInt("007");
+const a = parseInt("007");
 ```
 
 上述函数将字符串 `007` 转换为整数 `7`。 如果字符串中的第一个字符不能转换为数字，则返回 `NaN`。
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md
index 16dc56565cf..fa7e32d9c24 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md
@@ -14,7 +14,7 @@ dashedName: using-objects-for-lookups
 这是简单的反向字母表：
 
 ```js
-var alpha = {
+const alpha = {
   1:"Z",
   2:"Y",
   3:"X",
@@ -24,10 +24,11 @@ var alpha = {
   25:"B",
   26:"A"
 };
+
 alpha[2];
 alpha[24];
 
-var value = 2;
+const value = 2;
 alpha[value];
 ```
 
@@ -102,7 +103,7 @@ assert(
 ```js
 // Setup
 function phoneticLookup(val) {
-  var result = "";
+  let result = "";
 
   // Only change code below this line
   switch(val) {
@@ -136,9 +137,9 @@ phoneticLookup("charlie");
 
 ```js
 function phoneticLookup(val) {
-  var result = "";
+  let result = "";
 
-  var lookup = {
+  const lookup = {
     alpha: "Adams",
     bravo: "Boston",
     charlie: "Chicago",
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md
index 9551e57fdac..db8d8538783 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md
@@ -16,7 +16,7 @@ dashedName: word-blanks
 思考一下这句话 - It was really **\_\_\_\_**, and we **\_\_\_\_** ourselves **\_\_\_\_**。 这句话有三个缺失的部分 - 形容词、动词和副词，选择合适单词填入完成它。 然后将完成的句子赋值给变量，如下所示：
 
 ```js
-var sentence = "It was really " + "hot" + ", and we " + "laughed" + " ourselves " + "silly" + ".";
+const sentence = "It was really " + "hot" + ", and we " + "laughed" + " ourselves " + "silly" + ".";
 ```
 
 # --instructions--
@@ -84,24 +84,24 @@ const removeAssignments = str => str
 ## --seed-contents--
 
 ```js
-var myNoun = "dog";
-var myAdjective = "big";
-var myVerb = "ran";
-var myAdverb = "quickly";
+const myNoun = "dog";
+const myAdjective = "big";
+const myVerb = "ran";
+const myAdverb = "quickly";
 
 // Only change code below this line
-var wordBlanks = ""; // Change this line
+const wordBlanks = ""; // Change this line
 // Only change code above this line
 ```
 
 # --solutions--
 
 ```js
-var myNoun = "dog";
-var myAdjective = "big";
-var myVerb = "ran";
-var myAdverb = "quickly";
+const myNoun = "dog";
+const myAdjective = "big";
+const myVerb = "ran";
+const myAdverb = "quickly";
 
-var wordBlanks = "Once there was a " + myNoun + " which was very " + myAdjective + ". ";
+let wordBlanks = "Once there was a " + myNoun + " which was very " + myAdjective + ". ";
 wordBlanks += "It " + myVerb + " " + myAdverb + " around the yard.";
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md
index 06308ab6f24..a8fa46301d5 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md
@@ -13,7 +13,7 @@ dashedName: add-elements-to-the-end-of-an-array-using-concat-instead-of-push
 上一个挑战介绍了 `concat` 方法，这是一种在不改变原始数组的前提下，将数组组合成新数组的方法。 将 `concat` 方法与 `push` 方法做比较。 `push` 将元素添加到调用它的数组的末尾，这样会改变该数组。 举个例子：
 
 ```js
-var arr = [1, 2, 3];
+const arr = [1, 2, 3];
 arr.push([4, 5, 6]);
 ```
 
@@ -71,8 +71,9 @@ function nonMutatingPush(original, newItem) {
 
   // Only change code above this line
 }
-var first = [1, 2, 3];
-var second = [4, 5];
+
+const first = [1, 2, 3];
+const second = [4, 5];
 nonMutatingPush(first, second);
 ```
 
@@ -82,7 +83,6 @@ nonMutatingPush(first, second);
 function nonMutatingPush(original, newItem) {
   return original.concat(newItem);
 }
-var first = [1, 2, 3];
-var second = [4, 5];
-nonMutatingPush(first, second);
+const first = [1, 2, 3];
+const second = [4, 5];
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md
index 70e6b984cbd..c6580bbf5ff 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md
@@ -77,7 +77,6 @@ function urlSlug(title) {
 # --solutions--
 
 ```js
-// Only change code below this line
 function urlSlug(title) {
   return title.trim().split(/\s+/).join("-").toLowerCase();
 }
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md
index deeeb4d8ead..33c39a49dea 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md
@@ -57,9 +57,9 @@ assert(__newValue === 5);
 
 ```js
 // The global variable
-var fixedValue = 4;
+let fixedValue = 4;
 
-function incrementer () {
+function incrementer() {
   // Only change code below this line
 
 
@@ -70,7 +70,7 @@ function incrementer () {
 # --solutions--
 
 ```js
-var fixedValue = 4
+let fixedValue = 4
 
 function incrementer() {
   return fixedValue + 1
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md
index 7ae48edd2ea..06500eb5fa7 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md
@@ -13,8 +13,8 @@ dashedName: combine-an-array-into-a-string-using-the-join-method
 举个例子：
 
 ```js
-var arr = ["Hello", "World"];
-var str = arr.join(" ");
+const arr = ["Hello", "World"];
+const str = arr.join(" ");
 ```
 
 `str` 的值应该是字符串 `Hello World`。
@@ -76,6 +76,7 @@ function sentensify(str) {
 
   // Only change code above this line
 }
+
 sentensify("May-the-force-be-with-you");
 ```
 
@@ -83,8 +84,6 @@ sentensify("May-the-force-be-with-you");
 
 ```js
 function sentensify(str) {
-  // Only change code below this line
   return str.split(/\W/).join(' ');
-  // Only change code above this line
 }
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md
index 6e6e4627652..9c3f6b58acb 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md
@@ -60,8 +60,9 @@ function nonMutatingConcat(original, attach) {
 
   // Only change code above this line
 }
-var first = [1, 2, 3];
-var second = [4, 5];
+
+const first = [1, 2, 3];
+const second = [4, 5];
 nonMutatingConcat(first, second);
 ```
 
@@ -69,11 +70,8 @@ nonMutatingConcat(first, second);
 
 ```js
 function nonMutatingConcat(original, attach) {
-  // Only change code below this line
   return original.concat(attach);
-  // Only change code above this line
 }
-var first = [1, 2, 3];
-var second = [4, 5];
-nonMutatingConcat(first, second);
+const first = [1, 2, 3];
+const second = [4, 5];
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md
index 03bc9739911..8d8c7d8eb11 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md
@@ -38,17 +38,17 @@ assert(!code.match(/\.?[\s\S]*?map/g));
 
 ```js
 // The global variable
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myMap = function(callback) {
-  var newArray = [];
+  const newArray = [];
   // Only change code below this line
 
   // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myMap(function(item) {
+const new_s = s.myMap(function(item) {
   return item * 2;
 });
 ```
@@ -56,20 +56,17 @@ var new_s = s.myMap(function(item) {
 # --solutions--
 
 ```js
-// the global Array
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myMap = function(callback) {
-  var newArray = [];
-  // Only change code below this line
-  for (var elem of this) {
+  const newArray = [];
+  for (const elem of this) {
     newArray.push(callback(elem));
   }
-  // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myMap(function(item) {
+const new_s = s.myMap(function(item) {
   return item * 2;
 });
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md
index 08c03f10d0c..c778c603199 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md
@@ -34,16 +34,16 @@ assert(!code.match(/\.?[\s\S]*?filter/g));
 
 ```js
 // The global variable
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myFilter = function(callback) {
   // Only change code below this line
-  var newArray = [];
+  const newArray = [];
   // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myFilter(function(item) {
+const new_s = s.myFilter(function(item) {
   return item % 2 === 1;
 });
 ```
@@ -51,20 +51,17 @@ var new_s = s.myFilter(function(item) {
 # --solutions--
 
 ```js
-// the global Array
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myFilter = function(callback) {
-  var newArray = [];
-  // Only change code below this line
+  const newArray = [];
   for (let i = 0; i < this.length; i++) {
     if (callback(this[i])) newArray.push(this[i]);
   }
-  // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myFilter(function(item) {
+const new_s = s.myFilter(function(item) {
   return item % 2 === 1;
 });
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md
index 4cdb47a553c..66fbedf4158 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md
@@ -35,7 +35,7 @@ curried(1)(2)
 柯里化在不能一次为函数提供所有参数情况下很有用。 因为它可以将每个函数的调用保存到一个变量中，该变量将保存返回的函数引用，该引用在下一个参数可用时接受该参数。 下面是使用柯里化函数的例子：
 
 ```js
-var funcForY = curried(1);
+const funcForY = curried(1);
 console.log(funcForY(2)); // 3
 ```
 
@@ -45,7 +45,8 @@ console.log(funcForY(2)); // 3
 function impartial(x, y, z) {
   return x + y + z;
 }
-var partialFn = impartial.bind(this, 1, 2);
+
+const partialFn = impartial.bind(this, 1, 2);
 partialFn(10); // 13
 ```
 
@@ -90,6 +91,7 @@ function add(x) {
 
   // Only change code above this line
 }
+
 add(10)(20)(30);
 ```
 
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md
index 0b02fd625d6..8b4de734169 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md
@@ -53,10 +53,10 @@ assert(__newValue === 5);
 
 ```js
 // The global variable
-var fixedValue = 4;
+let fixedValue = 4;
 
 // Only change code below this line
-function incrementer () {
+function incrementer() {
 
 
   // Only change code above this line
@@ -66,15 +66,9 @@ function incrementer () {
 # --solutions--
 
 ```js
-// The global variable
-var fixedValue = 4;
+let fixedValue = 4;
 
-// Only change code below this line
-function incrementer (fixedValue) {
+function incrementer(fixedValue) {
   return fixedValue + 1;
-
-  // Only change code above this line
 }
-
-
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md
index 9da5369aeed..722b2349078 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md
@@ -11,7 +11,7 @@ dashedName: remove-elements-from-an-array-using-slice-instead-of-splice
 使用数组时经常遇到要删除一些元素并保留数组剩余部分的情况。 为此，JavaScript 提供了 `splice` 方法，它接收两个参数：从哪里开始删除项目的索引，和要删除的项目数。 如果没有提供第二个参数，默认情况下是移除一直到结尾的所有元素。 但 `splice` 方法会改变调用它的原始数组。 举个例子：
 
 ```js
-var cities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
+const cities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
 cities.splice(3, 1);
 ```
 
@@ -69,7 +69,8 @@ function nonMutatingSplice(cities) {
 
   // Only change code above this line
 }
-var inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
+
+const inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
 nonMutatingSplice(inputCities);
 ```
 
@@ -77,10 +78,7 @@ nonMutatingSplice(inputCities);
 
 ```js
 function nonMutatingSplice(cities) {
-  // Only change code below this line
   return cities.slice(0,3);
-  // Only change code above this line
 }
-var inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
-nonMutatingSplice(inputCities);
+const inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md
index db2bbd2632a..f4531202279 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md
@@ -68,24 +68,23 @@ assert(JSON.stringify(nonMutatingSort([140000, 104, 99])) ===
 ## --seed-contents--
 
 ```js
-var globalArray = [5, 6, 3, 2, 9];
+const globalArray = [5, 6, 3, 2, 9];
+
 function nonMutatingSort(arr) {
   // Only change code below this line
 
 
   // Only change code above this line
 }
+
 nonMutatingSort(globalArray);
 ```
 
 # --solutions--
 
 ```js
-var globalArray = [5, 6, 3, 2, 9];
+const globalArray = [5, 6, 3, 2, 9];
 function nonMutatingSort(arr) {
-  // Only change code below this line
   return [].concat(arr).sort((a,b) => a-b);
-  // Only change code above this line
 }
-nonMutatingSort(globalArray);
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md
index bce119c0793..f8b1e266ab2 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md
@@ -13,8 +13,8 @@ dashedName: return-part-of-an-array-using-the-slice-method
 举个例子：
 
 ```js
-var arr = ["Cat", "Dog", "Tiger", "Zebra"];
-var newArray = arr.slice(1, 3);
+const arr = ["Cat", "Dog", "Tiger", "Zebra"];
+const newArray = arr.slice(1, 3);
 ```
 
 `newArray` 值为 `["Dog", "Tiger"]`
@@ -78,7 +78,8 @@ function sliceArray(anim, beginSlice, endSlice) {
 
   // Only change code above this line
 }
-var inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
+
+const inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
 sliceArray(inputAnim, 1, 3);
 ```
 
@@ -86,10 +87,7 @@ sliceArray(inputAnim, 1, 3);
 
 ```js
 function sliceArray(anim, beginSlice, endSlice) {
-  // Only change code below this line
-  return anim.slice(beginSlice, endSlice)
-  // Only change code above this line
+  return anim.slice(beginSlice, endSlice);
 }
-var inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
-sliceArray(inputAnim, 1, 3);
+const inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md
index 5f350cdf75b..519880bd8fd 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md
@@ -18,6 +18,7 @@ function ascendingOrder(arr) {
     return a - b;
   });
 }
+
 ascendingOrder([1, 5, 2, 3, 4]);
 ```
 
@@ -29,6 +30,7 @@ function reverseAlpha(arr) {
     return a === b ? 0 : a < b ? 1 : -1;
   });
 }
+
 reverseAlpha(['l', 'h', 'z', 'b', 's']);
 ```
 
@@ -86,6 +88,7 @@ function alphabeticalOrder(arr) {
   return arr
   // Only change code above this line
 }
+
 alphabeticalOrder(["a", "d", "c", "a", "z", "g"]);
 ```
 
@@ -93,9 +96,6 @@ alphabeticalOrder(["a", "d", "c", "a", "z", "g"]);
 
 ```js
 function alphabeticalOrder(arr) {
-  // Only change code below this line
   return arr.sort();
-  // Only change code above this line
 }
-alphabeticalOrder(["a", "d", "c", "a", "z", "g"]);
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md
index f8721591aee..c4cf7eb3e4d 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md
@@ -13,11 +13,11 @@ dashedName: split-a-string-into-an-array-using-the-split-method
 下面是两个用空格分隔一个字符串的例子，另一个是用数字的正则表达式分隔：
 
 ```js
-var str = "Hello World";
-var bySpace = str.split(" ");
+const str = "Hello World";
+const bySpace = str.split(" ");
 
-var otherString = "How9are7you2today";
-var byDigits = otherString.split(/\d/);
+const otherString = "How9are7you2today";
+const byDigits = otherString.split(/\d/);
 ```
 
 `bySpace` 将有值 `["Hello", "World"]`，`byDigits` 将有值 `["How", "are", "you", "today"]`。
@@ -74,6 +74,7 @@ function splitify(str) {
 
   // Only change code above this line
 }
+
 splitify("Hello World,I-am code");
 ```
 
@@ -81,8 +82,6 @@ splitify("Hello World,I-am code");
 
 ```js
 function splitify(str) {
-  // Only change code below this line
   return str.split(/\W/);
-  // Only change code above this line
 }
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md
index f2793fa149e..4638766ff06 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md
@@ -59,29 +59,29 @@ assert.deepEqual(finalTabs.tabs, [
 
 ```js
 // tabs is an array of titles of each site open within the window
-var Window = function(tabs) {
+const Window = function(tabs) {
   this.tabs = tabs; // We keep a record of the array inside the object
 };
 
 // When you join two windows into one window
-Window.prototype.join = function (otherWindow) {
+Window.prototype.join = function(otherWindow) {
   this.tabs = this.tabs.concat(otherWindow.tabs);
   return this;
 };
 
 // When you open a new tab at the end
-Window.prototype.tabOpen = function (tab) {
+Window.prototype.tabOpen = function(tab) {
   this.tabs.push('new tab'); // Let's open a new tab for now
   return this;
 };
 
 // When you close a tab
-Window.prototype.tabClose = function (index) {
+Window.prototype.tabClose = function(index) {
 
   // Only change code below this line
 
-  var tabsBeforeIndex = this.tabs.splice(0, index); // Get the tabs before the tab
-  var tabsAfterIndex = this.tabs.splice(index + 1); // Get the tabs after the tab
+  const tabsBeforeIndex = this.tabs.splice(0, index); // Get the tabs before the tab
+  const tabsAfterIndex = this.tabs.splice(index + 1); // Get the tabs after the tab
 
   this.tabs = tabsBeforeIndex.concat(tabsAfterIndex); // Join them together
 
@@ -91,12 +91,12 @@ Window.prototype.tabClose = function (index) {
  };
 
 // Let's create three browser windows
-var workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']); // Your mailbox, drive, and other work sites
-var socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']); // Social sites
-var videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']); // Entertainment sites
+const workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']); // Your mailbox, drive, and other work sites
+const socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']); // Social sites
+const videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']); // Entertainment sites
 
 // Now perform the tab opening, closing, and other operations
-var finalTabs = socialWindow
+const finalTabs = socialWindow
   .tabOpen() // Open a new tab for cat memes
   .join(videoWindow.tabClose(2)) // Close third tab in video window, and join
   .join(workWindow.tabClose(1).tabOpen());
@@ -106,40 +106,34 @@ console.log(finalTabs.tabs);
 # --solutions--
 
 ```js
-// tabs is an array of titles of each site open within the window
-var Window = function(tabs) {
-  this.tabs = tabs; // We keep a record of the array inside the object
+const Window = function(tabs) {
+  this.tabs = tabs;
 };
 
-// When you join two windows into one window
-Window.prototype.join = function (otherWindow) {
+Window.prototype.join = function(otherWindow) {
   this.tabs = this.tabs.concat(otherWindow.tabs);
   return this;
 };
 
-// When you open a new tab at the end
-Window.prototype.tabOpen = function (tab) {
-  this.tabs.push('new tab'); // Let's open a new tab for now
+Window.prototype.tabOpen = function(tab) {
+  this.tabs.push('new tab');
   return this;
 };
 
-// When you close a tab
-Window.prototype.tabClose = function (index) {
-  var tabsBeforeIndex = this.tabs.slice(0, index); // Get the tabs before the tab
-  var tabsAfterIndex = this.tabs.slice(index + 1); // Get the tabs after the tab
+Window.prototype.tabClose = function(index) {
+  const tabsBeforeIndex = this.tabs.slice(0, index);
+  const tabsAfterIndex = this.tabs.slice(index + 1);
 
-  this.tabs = tabsBeforeIndex.concat(tabsAfterIndex); // Join them together
+  this.tabs = tabsBeforeIndex.concat(tabsAfterIndex);
   return this;
  };
 
-// Let's create three browser windows
-var workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']); // Your mailbox, drive, and other work sites
-var socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']); // Social sites
-var videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']); //  Entertainment sites
+const workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']);
+const socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']);
+const videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']);
 
-// Now perform the tab opening, closing, and other operations
-var finalTabs = socialWindow
-  .tabOpen() // Open a new tab for cat memes
-  .join(videoWindow.tabClose(2)) // Close third tab in video window, and join
+const finalTabs = socialWindow
+  .tabOpen()
+  .join(videoWindow.tabClose(2))
   .join(workWindow.tabClose(1).tabOpen());
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md
index dd7cd22c7bd..381c708edaf 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md
@@ -13,7 +13,8 @@ dashedName: use-the-every-method-to-check-that-every-element-in-an-array-meets-a
 举个例子，下面的代码检测数组 `numbers` 的所有元素是否都小于 10：
 
 ```js
-var numbers = [1, 5, 8, 0, 10, 11];
+const numbers = [1, 5, 8, 0, 10, 11];
+
 numbers.every(function(currentValue) {
   return currentValue < 10;
 });
@@ -62,6 +63,7 @@ function checkPositive(arr) {
 
   // Only change code above this line
 }
+
 checkPositive([1, 2, 3, -4, 5]);
 ```
 
@@ -69,9 +71,6 @@ checkPositive([1, 2, 3, -4, 5]);
 
 ```js
 function checkPositive(arr) {
-  // Only change code below this line
   return arr.every(num => num > 0);
-  // Only change code above this line
 }
-checkPositive([1, 2, 3, -4, 5]);
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md
index 9574b365459..e3475480862 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md
@@ -93,7 +93,7 @@ assert(getRating(watchList.filter((_, i) => i < 1 || i > 2)) === 8.55);
 
 ```js
 // The global variable
-var watchList = [
+const watchList = [
   {
     "Title": "Inception",
     "Year": "2010",
@@ -206,22 +206,22 @@ var watchList = [
   }
 ];
 
-function getRating(watchList){
+function getRating(watchList) {
   // Only change code below this line
-  var averageRating;
+  let averageRating;
 
 
   // Only change code above this line
   return averageRating;
 }
+
 console.log(getRating(watchList));
 ```
 
 # --solutions--
 
 ```js
-// The global variable
-var watchList = [
+const watchList = [
   {
     "Title": "Inception",
     "Year": "2010",
@@ -334,8 +334,8 @@ var watchList = [
   }
 ];
 
-function getRating(watchList){
-  var averageRating;
+function getRating(watchList) {
+  let averageRating;
   const rating = watchList
     .filter(obj => obj.Director === "Christopher Nolan")
     .map(obj => Number(obj.imdbRating));
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md
index 3a631b5671d..9ddde647cae 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md
@@ -13,7 +13,8 @@ dashedName: use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-cr
 举个例子，下面的代码检测数组`numbers`中是否有元素小于 10：
 
 ```js
-var numbers = [10, 50, 8, 220, 110, 11];
+const numbers = [10, 50, 8, 220, 110, 11];
+
 numbers.some(function(currentValue) {
   return currentValue < 10;
 });
@@ -62,6 +63,7 @@ function checkPositive(arr) {
 
   // Only change code above this line
 }
+
 checkPositive([1, 2, 3, -4, 5]);
 ```
 
@@ -69,9 +71,6 @@ checkPositive([1, 2, 3, -4, 5]);
 
 ```js
 function checkPositive(arr) {
-  // Only change code below this line
   return arr.some(elem => elem > 0);
-  // Only change code above this line
 }
-checkPositive([1, 2, 3, -4, 5]);
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md
index 7e437f8c06e..d8231ba7e66 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md
@@ -157,7 +157,7 @@ assert(diffArray([1, 'calf', 3, 'piglet'], [7, 'filly']).length === 6);
 
 ```js
 function diffArray(arr1, arr2) {
-  var newArr = [];
+  const newArr = [];
   return newArr;
 }
 
@@ -168,13 +168,12 @@ diffArray([1, 2, 3, 5], [1, 2, 3, 4, 5]);
 
 ```js
 function diffArray(arr1, arr2) {
-  var newArr = [];
-  var h1 = Object.create(null);
+  const newArr = [];
+  const h1 = Object.create(null);
   arr1.forEach(function(e) {
     h1[e] = e;
   });
-
-  var h2 = Object.create(null);
+  const h2 = Object.create(null);
   arr2.forEach(function(e) {
     h2[e] = e;
   });
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md
index ca33f0cd92a..2a4bc27f545 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md
@@ -148,7 +148,7 @@ if(bob){
 ## --seed-contents--
 
 ```js
-var Person = function(firstAndLast) {
+const Person = function(firstAndLast) {
   // Only change code below this line
   // Complete the method below and implement the others similarly
   this.getFullName = function() {
@@ -157,16 +157,16 @@ var Person = function(firstAndLast) {
   return firstAndLast;
 };
 
-var bob = new Person('Bob Ross');
+const bob = new Person('Bob Ross');
 bob.getFullName();
 ```
 
 # --solutions--
 
 ```js
-var Person = function(firstAndLast) {
+const Person = function(firstAndLast) {
 
-  var firstName, lastName;
+  let firstName, lastName;
 
   function updateName(str) {
     firstName = str.split(" ")[0];
@@ -201,6 +201,6 @@ var Person = function(firstAndLast) {
   };
 };
 
-var bob = new Person('Bob Ross');
+const bob = new Person('Bob Ross');
 bob.getFullName();
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md
index 472c9388eec..d53ca443dbe 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md
@@ -51,8 +51,8 @@ assert.deepEqual(
 
 ```js
 function orbitalPeriod(arr) {
-  var GM = 398600.4418;
-  var earthRadius = 6367.4447;
+  const GM = 398600.4418;
+  const earthRadius = 6367.4447;
   return arr;
 }
 
@@ -63,9 +63,9 @@ orbitalPeriod([{name : "sputnik", avgAlt : 35873.5553}]);
 
 ```js
 function orbitalPeriod(arr) {
-  var GM = 398600.4418;
-  var earthRadius = 6367.4447;
-  var TAU = 2 * Math.PI;
+  const GM = 398600.4418;
+  const earthRadius = 6367.4447;
+  const TAU = 2 * Math.PI;
   return arr.map(function(obj) {
     return {
       name: obj.name,
@@ -73,6 +73,4 @@ function orbitalPeriod(arr) {
     };
   });
 }
-
-orbitalPeriod([{name : "sputkin", avgAlt : 35873.5553}]);
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md
index 2c8092ea416..ff30a4a4e3c 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md
@@ -61,7 +61,6 @@ function smallestCommons(arr) {
   return arr;
 }
 
-
 smallestCommons([1,5]);
 ```
 
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md
index f972afdc1e4..40a6ba7a5ab 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md
@@ -103,7 +103,7 @@ assert.deepEqual(
 
 ```js
 function whatIsInAName(collection, source) {
-  var arr = [];
+  const arr = [];
   // Only change code below this line
 
 
@@ -118,8 +118,8 @@ whatIsInAName([{ first: "Romeo", last: "Montague" }, { first: "Mercutio", last:
 
 ```js
 function whatIsInAName(collection, source) {
-  var arr = [];
-  var keys = Object.keys(source);
+  const arr = [];
+  const keys = Object.keys(source);
   collection.forEach(function(e) {
     if(keys.every(function(key) {return e[key] === source[key];})) {
       arr.push(e);
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md
index 2b7edcaa944..67429f511eb 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md
@@ -51,7 +51,6 @@ assert(
 
 ```js
 function rot13(str) {
-
   return str;
 }
 
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md
index f89918bebd4..a81e80a968e 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md
@@ -186,7 +186,7 @@ assert.deepEqual(
 
 ```js
 function checkCashRegister(price, cash, cid) {
-  var change;
+  let change;
   return change;
 }
 
@@ -196,54 +196,57 @@ checkCashRegister(19.5, 20, [["PENNY", 1.01], ["NICKEL", 2.05], ["DIME", 3.1], [
 # --solutions--
 
 ```js
-var denom = [
-    { name: 'ONE HUNDRED', val: 100},
-    { name: 'TWENTY', val: 20},
-    { name: 'TEN', val: 10},
-    { name: 'FIVE', val: 5},
-    { name: 'ONE', val: 1},
-    { name: 'QUARTER', val: 0.25},
-    { name: 'DIME', val: 0.1},
-    { name: 'NICKEL', val: 0.05},
-    { name: 'PENNY', val: 0.01}
+const denom = [
+  { name: "ONE HUNDRED", val: 100 },
+  { name: "TWENTY", val: 20 },
+  { name: "TEN", val: 10 },
+  { name: "FIVE", val: 5 },
+  { name: "ONE", val: 1 },
+  { name: "QUARTER", val: 0.25 },
+  { name: "DIME", val: 0.1 },
+  { name: "NICKEL", val: 0.05 },
+  { name: "PENNY", val: 0.01 },
 ];
 
 function checkCashRegister(price, cash, cid) {
- var output = {status: null, change: []};
- var change = cash - price;
- var register = cid.reduce(function(acc, curr) {
- acc.total += curr[1];
- acc[curr[0]] = curr[1];
- return acc;
- }, {total: 0});
- if(register.total === change) {
- output.status = 'CLOSED';
- output.change = cid;
- return output;
- }
- if(register.total < change) {
- output.status = 'INSUFFICIENT_FUNDS';
- return output;
- }
- var change_arr = denom.reduce(function(acc, curr) {
- var value = 0;
- while(register[curr.name] > 0 && change >= curr.val) {
- change -= curr.val;
- register[curr.name] -= curr.val;
- value += curr.val;
- change = Math.round(change * 100) / 100;
- }
- if(value > 0) {
- acc.push([ curr.name, value ]);
- }
- return acc;
- }, []);
- if(change_arr.length < 1 || change > 0) {
- output.status = 'INSUFFICIENT_FUNDS';
- return output;
- }
- output.status = 'OPEN';
- output.change = change_arr;
- return output;
+  const output = { status: null, change: [] };
+  let change = cash - price;
+  const register = cid.reduce(
+    function (acc, curr) {
+      acc.total += curr[1];
+      acc[curr[0]] = curr[1];
+      return acc;
+    },
+    { total: 0 }
+  );
+  if (register.total === change) {
+    output.status = "CLOSED";
+    output.change = cid;
+    return output;
+  }
+  if (register.total < change) {
+    output.status = "INSUFFICIENT_FUNDS";
+    return output;
+  }
+  const change_arr = denom.reduce(function (acc, curr) {
+    let value = 0;
+    while (register[curr.name] > 0 && change >= curr.val) {
+      change -= curr.val;
+      register[curr.name] -= curr.val;
+      value += curr.val;
+      change = Math.round(change * 100) / 100;
+    }
+    if (value > 0) {
+      acc.push([curr.name, value]);
+    }
+    return acc;
+  }, []);
+  if (change_arr.length < 1 || change > 0) {
+    output.status = "INSUFFICIENT_FUNDS";
+    return output;
+  }
+  output.status = "OPEN";
+  output.change = change_arr;
+  return output;
 }
 ```
diff --git a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md
index 5443a90f4be..969f98023ce 100644
--- a/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md
+++ b/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md
@@ -107,8 +107,6 @@ function palindrome(str) {
   return true;
 }
 
-
-
 palindrome("eye");
 ```
 
diff --git a/curriculum/challenges/espanol/01-responsive-web-design/applied-accessibility/use-headings-to-show-hierarchical-relationships-of-content.md b/curriculum/challenges/espanol/01-responsive-web-design/applied-accessibility/use-headings-to-show-hierarchical-relationships-of-content.md
index 0fde73a9ebe..8c53f2cfb43 100644
--- a/curriculum/challenges/espanol/01-responsive-web-design/applied-accessibility/use-headings-to-show-hierarchical-relationships-of-content.md
+++ b/curriculum/challenges/espanol/01-responsive-web-design/applied-accessibility/use-headings-to-show-hierarchical-relationships-of-content.md
@@ -17,7 +17,7 @@ Si estuvieras escribiendo un documento con una introducción, un cuerpo y una co
 
 Los títulos con rango igual (o superior) comienzan nuevas secciones implícitas, los títulos con rango inferior comienzan subsecciones de la anterior.
 
-Como ejemplo, una página con un elemento `h2` seguido de varias subsecciones marcadas con etiquetas `h4` confundirá a un lector de pantalla. Con seis opciones, es tentador usar una etiqueta porque se ve mejor en un navegador, pero puede usar CSS para editar el tamaño relativo.
+Como un ejemplo, una página con un elemento `h2` seguido por varias subsecciones etiquetadas con elementos `h4` confundiría a un lector de pantalla. Con seis opciones, es tentador usar una etiqueta porque se ve mejor en un navegador, pero puede usar CSS para editar el tamaño relativo.
 
 Un punto final, cada página siempre debe tener un (y solo un) elemento `h1`, que es el tema principal de tu contenido. Este y los otros títulos son utilizados en parte por los motores de búsqueda para comprender el tema de la página.
 
@@ -27,7 +27,7 @@ Camper Cat quiere una página en su sitio dedicada a convertirse en un ninja. Ay
 
 # --hints--
 
-Tu código debe tener 6 etiquetas `h3`.
+Tu código debe tener 6 elementos `h3`.
 
 ```js
 assert($('h3').length === 6);
@@ -39,7 +39,7 @@ Tu código debe tener 6 etiquetas de cierre `h3`.
 assert((code.match(/\/h3/g) || []).length === 6);
 ```
 
-Tu código no debe tener ninguna etiqueta `h5`.
+Tu código no debe tener ningún elemento `h5`.
 
 ```js
 assert($('h5').length === 0);
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md
index 24ccd0b48cc..96e7c2919b8 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md
@@ -18,9 +18,9 @@ Los índices de los arreglos se escriben en la misma notación de corchetes que
 **Ejemplo**
 
 ```js
-var array = [50,60,70];
+const array = [50, 60, 70];
 array[0];
-var data = array[1];
+const data = array[1];
 ```
 
 `array[0]` ahora es `50` y `data` tiene el valor `60`.
@@ -76,7 +76,7 @@ if(typeof myArray !== "undefined" && typeof myData !== "undefined"){(function(y,
 ## --seed-contents--
 
 ```js
-var myArray = [50,60,70];
+const myArray = [50, 60, 70];
 
 
 ```
@@ -84,6 +84,6 @@ var myArray = [50,60,70];
 # --solutions--
 
 ```js
-var myArray = [50,60,70];
-var myData = myArray[0];
+const myArray = [50, 60, 70];
+const myData = myArray[0];
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md
index 80adef46995..ebbaf87236f 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md
@@ -14,12 +14,13 @@ Se puede pensar que un arreglo <dfn>multidimensional</dfn> es como un *arreglo d
 **Ejemplo**
 
 ```js
-var arr = [
-  [1,2,3],
-  [4,5,6],
-  [7,8,9],
-  [[10,11,12], 13, 14]
+const arr = [
+  [1, 2, 3],
+  [4, 5, 6],
+  [7, 8, 9],
+  [[10, 11, 12], 13, 14]
 ];
+
 arr[3];
 arr[3][0];
 arr[3][0][1];
@@ -58,14 +59,19 @@ if(typeof myArray !== "undefined"){(function(){return "myData: " + myData + " my
 ## --seed-contents--
 
 ```js
-var myArray = [[1,2,3], [4,5,6], [7,8,9], [[10,11,12], 13, 14]];
+const myArray = [
+  [1, 2, 3],
+  [4, 5, 6],
+  [7, 8, 9],
+  [[10, 11, 12], 13, 14],
+];
 
-var myData = myArray[0][0];
+const myData = myArray[0][0];
 ```
 
 # --solutions--
 
 ```js
-var myArray = [[1,2,3],[4,5,6], [7,8,9], [[10,11,12], 13, 14]];
-var myData = myArray[2][1];
+const myArray = [[1, 2, 3], [4, 5, 6], [7, 8, 9], [[10, 11, 12], 13, 14]];
+const myData = myArray[2][1];
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md
index 6cebd810d20..df2e59d88f8 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md
@@ -14,7 +14,7 @@ Como hemos visto en ejemplos anteriores, los objetos pueden contener tanto objet
 En el siguiente ejemplo, vemos cómo se accede a un arreglo anidado:
 
 ```js
-var ourPets = [
+const ourPets = [
   {
     animalType: "cat",
     names: [
@@ -32,6 +32,7 @@ var ourPets = [
     ]
   }
 ];
+
 ourPets[0].names[1];
 ourPets[1].names[0];
 ```
@@ -72,7 +73,7 @@ assert(/=\s*myPlants\[1\].list\[1\]/.test(code));
 ## --seed-contents--
 
 ```js
-var myPlants = [
+const myPlants = [
   {
     type: "flowers",
     list: [
@@ -91,13 +92,13 @@ var myPlants = [
   }
 ];
 
-var secondTree = "";
+const secondTree = "";
 ```
 
 # --solutions--
 
 ```js
-var myPlants = [
+const myPlants = [
   {
     type: "flowers",
     list: [
@@ -116,5 +117,5 @@ var myPlants = [
   }
 ];
 
-var secondTree = myPlants[1].list[1];
+const secondTree = myPlants[1].list[1];
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md
index 3b0275ecfd8..60c7312d987 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md
@@ -14,7 +14,7 @@ Se puede acceder a las sub propiedades de objetos encadenando la notación de pu
 Aquí hay un objeto anidado:
 
 ```js
-var ourStorage = {
+const ourStorage = {
   "desk": {
     "drawer": "stapler"
   },
@@ -26,6 +26,7 @@ var ourStorage = {
     "bottom drawer": "soda"
   }
 };
+
 ourStorage.cabinet["top drawer"].folder2;
 ourStorage.desk.drawer;
 ```
@@ -66,7 +67,7 @@ assert(/=\s*myStorage\.car\.inside\[\s*("|')glove box\1\s*\]/g.test(code));
 ## --seed-contents--
 
 ```js
-var myStorage = {
+const myStorage = {
   "car": {
     "inside": {
       "glove box": "maps",
@@ -78,13 +79,13 @@ var myStorage = {
   }
 };
 
-var gloveBoxContents = undefined;
+const gloveBoxContents = undefined;
 ```
 
 # --solutions--
 
 ```js
-var myStorage = {
+const myStorage = {
   "car":{
     "inside":{
       "glove box":"maps",
@@ -95,5 +96,5 @@ var myStorage = {
     }
   }
 };
-var gloveBoxContents = myStorage.car.inside["glove box"];
+const gloveBoxContents = myStorage.car.inside["glove box"];
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md
index f9b76e7b9a3..c81d4c88a3f 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md
@@ -16,11 +16,12 @@ Sin embargo, también puedes utilizar la notación de corchetes en las propiedad
 Aquí hay un ejemplo de cómo usar la notación de corchetes para leer la propiedad de un objeto:
 
 ```js
-var myObj = {
+const myObj = {
   "Space Name": "Kirk",
   "More Space": "Spock",
   "NoSpace": "USS Enterprise"
 };
+
 myObj["Space Name"];
 myObj['More Space'];
 myObj["NoSpace"];
@@ -78,26 +79,25 @@ assert(code.match(/testObj\s*?\[('|")[^'"]+\1\]/g).length > 1);
 
 ```js
 // Setup
-var testObj = {
+const testObj = {
   "an entree": "hamburger",
   "my side": "veggies",
   "the drink": "water"
 };
 
 // Only change code below this line
-
-var entreeValue = testObj;   // Change this line
-var drinkValue = testObj;    // Change this line
+const entreeValue = testObj;   // Change this line
+const drinkValue = testObj;    // Change this line
 ```
 
 # --solutions--
 
 ```js
-var testObj = {
+const testObj = {
   "an entree": "hamburger",
   "my side": "veggies",
   "the drink": "water"
 };
-var entreeValue = testObj["an entree"];
-var drinkValue = testObj['the drink'];
+const entreeValue = testObj["an entree"];
+const drinkValue = testObj['the drink'];
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md
index b76860c6fac..d6d9b3800ba 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md
@@ -16,15 +16,17 @@ La notación de puntos es lo que se usa cuando conoces el nombre de la propiedad
 Aquí hay un ejemplo de cómo usar la notación de puntos (`.`) para leer la propiedad de un objeto:
 
 ```js
-var myObj = {
+const myObj = {
   prop1: "val1",
   prop2: "val2"
 };
-var prop1val = myObj.prop1;
-var prop2val = myObj.prop2;
+
+const prop1val = myObj.prop1;
+const prop2val = myObj.prop2;
 ```
 
 `prop1val` tendrá una cadena con valor `val1` y `prop2val` tendrá una cadena con valor `val2`.
+
 # --instructions--
 
 Lee los valores de las propiedades de `testObj` utilizando la notación de puntos. Asigna la variable `hatValue` igual a la propiedad `hat` del objeto y asigna la variable `shirtValue` igual a la propiedad `shirt` del objeto.
@@ -73,27 +75,26 @@ assert(code.match(/testObj\.\w+/g).length > 1);
 
 ```js
 // Setup
-var testObj = {
+const testObj = {
   "hat": "ballcap",
   "shirt": "jersey",
   "shoes": "cleats"
 };
 
 // Only change code below this line
-
-var hatValue = testObj;      // Change this line
-var shirtValue = testObj;    // Change this line
+const hatValue = testObj;      // Change this line
+const shirtValue = testObj;    // Change this line
 ```
 
 # --solutions--
 
 ```js
-var testObj = {
+const testObj = {
   "hat": "ballcap",
   "shirt": "jersey",
   "shoes": "cleats"
 };
 
-var hatValue = testObj.hat;
-var shirtValue = testObj.shirt;
+const hatValue = testObj.hat;
+const shirtValue = testObj.shirt;
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md
index 543720a884e..03419b61091 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md
@@ -14,11 +14,14 @@ Otro uso de la notación de corchetes en objetos es acceder a una propiedad que
 Aquí hay un ejemplo del uso de una variable para acceder a una propiedad:
 
 ```js
-var dogs = {
-  Fido: "Mutt",  Hunter: "Doberman",  Snoopie: "Beagle"
+const dogs = {
+  Fido: "Mutt",
+  Hunter: "Doberman",
+  Snoopie: "Beagle"
 };
-var myDog = "Hunter";
-var myBreed = dogs[myDog];
+
+const myDog = "Hunter";
+const myBreed = dogs[myDog];
 console.log(myBreed);
 ```
 
@@ -27,14 +30,16 @@ La cadena `Doberman` se mostrará en la consola.
 Otra forma de usar este concepto es cuando el nombre de la propiedad se recoge dinámicamente durante la ejecución del programa, de la siguiente manera:
 
 ```js
-var someObj = {
+const someObj = {
   propName: "John"
 };
+
 function propPrefix(str) {
-  var s = "prop";
+  const s = "prop";
   return s + str;
 }
-var someProp = propPrefix("Name");
+
+const someProp = propPrefix("Name");
 console.log(someObj[someProp]);
 ```
 
@@ -96,26 +101,25 @@ if(typeof player !== "undefined"){(function(v){return v;})(player);}
 
 ```js
 // Setup
-var testObj = {
+const testObj = {
   12: "Namath",
   16: "Montana",
   19: "Unitas"
 };
 
 // Only change code below this line
-
-var playerNumber;       // Change this line
-var player = testObj;   // Change this line
+const playerNumber = 42;  // Change this line
+const player = testObj;   // Change this line
 ```
 
 # --solutions--
 
 ```js
-var testObj = {
+const testObj = {
   12: "Namath",
   16: "Montana",
   19: "Unitas"
 };
-var playerNumber = 16;
-var player = testObj[playerNumber];
+const playerNumber = 16;
+const player = testObj[playerNumber];
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md
index afe37c98cdb..2ca9f4d2e55 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md
@@ -28,7 +28,7 @@ Ahora cuando evaluemos `ourDog.bark`, obtendremos su ladrido, `bow-wow`.
 Por ejemplo:
 
 ```js
-var ourDog = {
+const ourDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
@@ -67,7 +67,7 @@ assert(!/bark[^\n]:/.test(code));
 ## --seed-contents--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
@@ -80,7 +80,7 @@ var myDog = {
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md
index 1673f7abbf3..42482299294 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md
@@ -18,7 +18,7 @@ JavaScript utiliza el símbolo `+` como un operador de adición cuando se coloca
 **Ejemplo:**
 
 ```js
-myVar = 5 + 10;
+const myVar = 5 + 10;
 ```
 
 `myVar` ahora tiene el valor `15`.
@@ -52,11 +52,11 @@ assert(/\+/.test(code));
 ## --seed-contents--
 
 ```js
-var sum = 10 + 0;
+const sum = 10 + 0;
 ```
 
 # --solutions--
 
 ```js
-var sum = 10 + 10;
+const sum = 10 + 10;
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md
index dd791bb2e2f..385ce1e84cb 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md
@@ -92,7 +92,7 @@ assert(code.match(/break/g).length > 2);
 
 ```js
 function switchOfStuff(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
 
@@ -108,7 +108,7 @@ switchOfStuff(1);
 
 ```js
 function switchOfStuff(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case "a":
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md
index b235bc75de7..de755d7e0a9 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md
@@ -14,8 +14,8 @@ Al igual que podemos construir una cadena sobre múltiples líneas a partir de l
 Ejemplo:
 
 ```js
-var anAdjective = "awesome!";
-var ourStr = "freeCodeCamp is ";
+const anAdjective = "awesome!";
+let ourStr = "freeCodeCamp is ";
 ourStr += anAdjective;
 ```
 
@@ -64,15 +64,14 @@ assert(code.match(/myStr\s*\+=\s*someAdjective\s*/).length > 0);
 
 ```js
 // Change code below this line
-
-var someAdjective;
-var myStr = "Learning to code is ";
+const someAdjective = "";
+let myStr = "Learning to code is ";
 ```
 
 # --solutions--
 
 ```js
-var someAdjective = "neat";
-var myStr = "Learning to code is ";
+const someAdjective = "neat";
+let myStr = "Learning to code is ";
 myStr += someAdjective;
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md
index 077f30206d6..b2fe618f9e8 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md
@@ -18,7 +18,7 @@ Los objetos son útiles para almacenar datos de forma estructurada y pueden repr
 Por ejemplo, aquí hay un objeto de gato:
 
 ```js
-var cat = {
+const cat = {
   "name": "Whiskers",
   "legs": 4,
   "tails": 1,
@@ -29,7 +29,7 @@ var cat = {
 En este ejemplo, todas las propiedades se almacenan como cadenas, como `name`, `legs` y `tails`. Sin embargo, también puedes utilizar números como propiedades. Incluso puedes omitir las comillas para las propiedades de cadenas de una sola palabra, de la siguiente manera:
 
 ```js
-var anotherObject = {
+const anotherObject = {
   make: "Ford",
   5: "five",
   "model": "focus"
@@ -139,18 +139,18 @@ assert(
 ## --seed-contents--
 
 ```js
-var myDog = {
-// Only change code below this line
+const myDog = {
+  // Only change code below this line
 
 
-// Only change code above this line
+  // Only change code above this line
 };
 ```
 
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md
index e162926ebe1..b88c232d19a 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md
@@ -16,7 +16,7 @@ El operador más básico es el de igualdad `==`. El operador de igualdad compara
 ```js
 function equalityTest(myVal) {
   if (myVal == 10) {
-     return "Equal";
+    return "Equal";
   }
   return "Not Equal";
 }
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md
index 555340698a7..da94c45a7c8 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md
@@ -20,7 +20,7 @@ para sumar `5` a `myVar`. Dado que se trata de un patrón tan común, hay operad
 Uno de estos operadores es el operador `+=`.
 
 ```js
-var myVar = 1;
+let myVar = 1;
 myVar += 5;
 console.log(myVar);
 ```
@@ -61,9 +61,9 @@ No debes modificar el código por encima del comentario especificado.
 
 ```js
 assert(
-  /var a = 3;/.test(code) &&
-    /var b = 17;/.test(code) &&
-    /var c = 12;/.test(code)
+  /let a = 3;/.test(code) &&
+    /let b = 17;/.test(code) &&
+    /let c = 12;/.test(code)
 );
 ```
 
@@ -78,9 +78,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 3;
-var b = 17;
-var c = 12;
+let a = 3;
+let b = 17;
+let c = 12;
 
 // Only change code below this line
 a = a + 12;
@@ -91,9 +91,9 @@ c = c + 7;
 # --solutions--
 
 ```js
-var a = 3;
-var b = 17;
-var c = 12;
+let a = 3;
+let b = 17;
+let c = 12;
 
 a += 12;
 b += 9;
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md
index 1ab106d4a57..25757dc71a3 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md
@@ -55,9 +55,9 @@ No debes modificar el código sobre el comentario especificado.
 
 ```js
 assert(
-  /var a = 48;/.test(code) &&
-    /var b = 108;/.test(code) &&
-    /var c = 33;/.test(code)
+  /let a = 48;/.test(code) &&
+    /let b = 108;/.test(code) &&
+    /let c = 33;/.test(code)
 );
 ```
 
@@ -72,9 +72,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 48;
-var b = 108;
-var c = 33;
+let a = 48;
+let b = 108;
+let c = 33;
 
 // Only change code below this line
 a = a / 12;
@@ -85,9 +85,9 @@ c = c / 11;
 # --solutions--
 
 ```js
-var a = 48;
-var b = 108;
-var c = 33;
+let a = 48;
+let b = 108;
+let c = 33;
 
 a /= 12;
 b /= 4;
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md
index 512e7f17f9a..1a75a65e83e 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md
@@ -55,9 +55,9 @@ No debes modificar el código sobre el comentario especificado.
 
 ```js
 assert(
-  /var a = 5;/.test(code) &&
-    /var b = 12;/.test(code) &&
-    /var c = 4\.6;/.test(code)
+  /let a = 5;/.test(code) &&
+    /let b = 12;/.test(code) &&
+    /let c = 4\.6;/.test(code)
 );
 ```
 
@@ -72,9 +72,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 5;
-var b = 12;
-var c = 4.6;
+let a = 5;
+let b = 12;
+let c = 4.6;
 
 // Only change code below this line
 a = a * 5;
@@ -85,9 +85,9 @@ c = c * 10;
 # --solutions--
 
 ```js
-var a = 5;
-var b = 12;
-var c = 4.6;
+let a = 5;
+let b = 12;
+let c = 4.6;
 
 a *= 5;
 b *= 3;
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md
index 99580fc9fca..38429d7c6ad 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md
@@ -55,7 +55,7 @@ No debes modificar el código sobre el comentario especificado.
 
 ```js
 assert(
-  /var a = 11;/.test(code) && /var b = 9;/.test(code) && /var c = 3;/.test(code)
+  /let a = 11;/.test(code) && /let b = 9;/.test(code) && /let c = 3;/.test(code)
 );
 ```
 
@@ -70,9 +70,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 11;
-var b = 9;
-var c = 3;
+let a = 11;
+let b = 9;
+let c = 3;
 
 // Only change code below this line
 a = a - 6;
@@ -83,9 +83,9 @@ c = c - 1;
 # --solutions--
 
 ```js
-var a = 11;
-var b = 9;
-var c = 3;
+let a = 11;
+let b = 9;
+let c = 3;
 
 a -= 6;
 b -= 15;
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md
index 6c8d8afa403..71f31f0e0b9 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md
@@ -16,7 +16,7 @@ También podemos utilizar el operador `+=` para <dfn>concatenar</dfn> una cadena
 Ejemplo:
 
 ```js
-var ourStr = "I come first. ";
+let ourStr = "I come first. ";
 ourStr += "I come second.";
 ```
 
@@ -57,14 +57,12 @@ assert(code.match(/myStr\s*\+=\s*(["']).*\1/g));
 ## --seed-contents--
 
 ```js
-// Only change code below this line
-
-var myStr;
+let myStr;
 ```
 
 # --solutions--
 
 ```js
-var myStr = "This is the first sentence. ";
+let myStr = "This is the first sentence. ";
 myStr += "This is the second sentence.";
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md
index f99326a40c4..8b05260f2e4 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md
@@ -14,8 +14,8 @@ A veces necesitarás construir una cadena, al estilo [Mad Libs](https://en.wikip
 Ejemplo:
 
 ```js
-var ourName = "freeCodeCamp";
-var ourStr = "Hello, our name is " + ourName + ", how are you?";
+const ourName = "freeCodeCamp";
+const ourStr = "Hello, our name is " + ourName + ", how are you?";
 ```
 
 `ourStr` tendrá como valor la cadena `Hello, our name is freeCodeCamp, how are you?`.
@@ -63,13 +63,13 @@ assert(code.match(/["']\s*\+\s*myName\s*\+\s*["']/g).length > 0);
 
 ```js
 // Only change code below this line
-var myName;
-var myStr;
+const myName = "";
+const myStr = "";
 ```
 
 # --solutions--
 
 ```js
-var myName = "Bob";
-var myStr = "My name is " + myName + " and I am well!";
+const myName = "Bob";
+const myStr = "My name is " + myName + " and I am well!";
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md
index 084a4b45b3a..6cf3bf07c14 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md
@@ -159,7 +159,7 @@ assert(
 ## --seed-contents--
 
 ```js
-var count = 0;
+let count = 0;
 
 function cc(card) {
   // Only change code below this line
@@ -175,7 +175,7 @@ cc(2); cc(3); cc(7); cc('K'); cc('A');
 # --solutions--
 
 ```js
-var count = 0;
+let count = 0;
 function cc(card) {
   switch(card) {
     case 2:
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md
index fb6e1605021..c548545829b 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md
@@ -42,13 +42,14 @@ assert(myDecimal % 1 != 0);
 ## --seed-contents--
 
 ```js
-var ourDecimal = 5.7;
+const ourDecimal = 5.7;
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myDecimal = 9.9;
+const myDecimal = 9.9;
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md
index 68a2a9a651e..ea3ec61d42c 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md
@@ -39,7 +39,7 @@ assert(myVar === 10);
 
 ```js
 assert(
-  /var\s*myVar\s*=\s*11;\s*\/*.*\s*([-]{2}\s*myVar|myVar\s*[-]{2});/.test(code)
+  /let\s*myVar\s*=\s*11;\s*\/*.*\s*([-]{2}\s*myVar|myVar\s*[-]{2});/.test(code)
 );
 ```
 
@@ -52,7 +52,7 @@ assert(/[-]{2}\s*myVar|myVar\s*[-]{2}/.test(code));
 No debes cambiar el código por encima del comentario especificado.
 
 ```js
-assert(/var myVar = 11;/.test(code));
+assert(/let myVar = 11;/.test(code));
 ```
 
 # --seed--
@@ -66,7 +66,7 @@ assert(/var myVar = 11;/.test(code));
 ## --seed-contents--
 
 ```js
-var myVar = 11;
+let myVar = 11;
 
 // Only change code below this line
 myVar = myVar - 1;
@@ -75,6 +75,6 @@ myVar = myVar - 1;
 # --solutions--
 
 ```js
-var myVar = 11;
+let myVar = 11;
 myVar--;
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md
index 4b06a101dae..0c4f33bb912 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md
@@ -18,7 +18,7 @@ delete ourDog.bark;
 Ejemplo:
 
 ```js
-var ourDog = {
+const ourDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
@@ -70,7 +70,7 @@ assert(code.match(/"tails": 1/g).length > 0);
 
 ```js
 // Setup
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
@@ -79,12 +79,13 @@ var myDog = {
 };
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md
index 084ee38e9f8..f5460a90165 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md
@@ -46,11 +46,11 @@ assert(code.match(/quotient/g).length === 1);
 ## --seed-contents--
 
 ```js
-var quotient = 0.0 / 2.0; // Change this line
+const quotient = 0.0 / 2.0; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var quotient = 4.4 / 2.0;
+const quotient = 4.4 / 2.0;
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md
index dd54212715b..b8cc296acad 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md
@@ -16,7 +16,7 @@ JavaScript utiliza el símbolo `/` para la división.
 **Ejemplo**
 
 ```js
-myVar = 16 / 2;
+const myVar = 16 / 2;
 ```
 
 `myVar` ahora tiene el valor `8`.
@@ -49,11 +49,11 @@ assert(/\d+\s*\/\s*\d+/.test(code));
 ## --seed-contents--
 
 ```js
-var quotient = 66 / 0;
+const quotient = 66 / 0;
 ```
 
 # --solutions--
 
 ```js
-var quotient = 66 / 33;
+const quotient = 66 / 33;
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md
index d56bf45c7b4..30bf2a478e5 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md
@@ -89,11 +89,11 @@ console.log('myStr:\n' + myStr);}})();
 ## --seed-contents--
 
 ```js
-var myStr; // Change this line
+const myStr = ""; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var myStr = "FirstLine\n\t\\SecondLine\nThirdLine";
+const myStr = "FirstLine\n\t\\SecondLine\nThirdLine";
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md
index e3414cf46c3..a4d96b88250 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md
@@ -14,7 +14,7 @@ Cuando estás definiendo una cadena debes comenzar y terminar con una comilla si
 En JavaScript, puedes <dfn>escapar</dfn> una comilla de considerarse un final de cadena colocando una <dfn>barra invertida</dfn> (`\`) delante de la comilla.
 
 ```js
-var sampleStr = "Alan said, \"Peter is learning JavaScript\".";
+const sampleStr = "Alan said, \"Peter is learning JavaScript\".";
 ```
 
 Esto indica a JavaScript que la siguiente comilla no es el final de la cadena, sino que debería aparecer dentro de la cadena. Así que si imprimieras esto en la consola, obtendrías:
@@ -62,11 +62,11 @@ assert(/I am a "double quoted" string inside "double quotes(\."|"\.)$/.test(mySt
 ## --seed-contents--
 
 ```js
-var myStr = ""; // Change this line
+const myStr = ""; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var myStr = "I am a \"double quoted\" string inside \"double quotes\".";
+const myStr = "I am a \"double quoted\" string inside \"double quotes\".";
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md
index 4b8339fc95e..4a008eae720 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md
@@ -31,7 +31,7 @@ Establece `remainder` igual al resto de `11` dividido entre `3` usando el operad
 La variable `remainder` debe inicializarse
 
 ```js
-assert(/var\s+?remainder/.test(code));
+assert(/(const|let|var)\s+?remainder/.test(code));
 ```
 
 El valor de `remainder` debe ser `2`
@@ -57,13 +57,11 @@ assert(/\s+?remainder\s*?=\s*?.*%.*;?/.test(code));
 ## --seed-contents--
 
 ```js
-// Only change code below this line
-
-var remainder;
+const remainder = 0;
 ```
 
 # --solutions--
 
 ```js
-var remainder =  11 % 3;
+const remainder = 11 % 3;
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md
index 54f2e81ca49..8567f1098d3 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md
@@ -14,9 +14,10 @@ Es posible tener variables <dfn>locales</dfn> y <dfn>globales</dfn> con el mismo
 En este ejemplo:
 
 ```js
-var someVar = "Hat";
+const someVar = "Hat";
+
 function myFun() {
-  var someVar = "Head";
+  const someVar = "Head";
   return someVar;
 }
 ```
@@ -53,13 +54,11 @@ assert(/return outerWear/.test(code));
 
 ```js
 // Setup
-var outerWear = "T-Shirt";
+const outerWear = "T-Shirt";
 
 function myOutfit() {
   // Only change code below this line
 
-
-
   // Only change code above this line
   return outerWear;
 }
@@ -70,9 +69,9 @@ myOutfit();
 # --solutions--
 
 ```js
-var outerWear = "T-Shirt";
+const outerWear = "T-Shirt";
 function myOutfit() {
-  var outerWear = "sweater";
+  const outerWear = "sweater";
   return outerWear;
 }
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md
index 9b4d455f528..3005d9fe81d 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md
@@ -90,7 +90,8 @@ assert(golfScore(5, 9) === 'Go Home!');
 ## --seed-contents--
 
 ```js
-var names = ["Hole-in-one!", "Eagle", "Birdie", "Par", "Bogey", "Double Bogey", "Go Home!"];
+const names = ["Hole-in-one!", "Eagle", "Birdie", "Par", "Bogey", "Double Bogey", "Go Home!"];
+
 function golfScore(par, strokes) {
   // Only change code below this line
 
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md
index 0327dea07cd..a0b31c5f345 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md
@@ -39,7 +39,7 @@ No debes utilizar el operador de asignación.
 
 ```js
 assert(
-  /var\s*myVar\s*=\s*87;\s*\/*.*\s*([+]{2}\s*myVar|myVar\s*[+]{2});/.test(code)
+  /let\s*myVar\s*=\s*87;\s*\/*.*\s*([+]{2}\s*myVar|myVar\s*[+]{2});/.test(code)
 );
 ```
 
@@ -52,7 +52,7 @@ assert(/[+]{2}\s*myVar|myVar\s*[+]{2}/.test(code));
 No debes cambiar el código por encima del comentario especificado.
 
 ```js
-assert(/var myVar = 87;/.test(code));
+assert(/let myVar = 87;/.test(code));
 ```
 
 # --seed--
@@ -66,7 +66,7 @@ assert(/var myVar = 87;/.test(code));
 ## --seed-contents--
 
 ```js
-var myVar = 87;
+let myVar = 87;
 
 // Only change code below this line
 myVar = myVar + 1;
@@ -75,6 +75,6 @@ myVar = myVar + 1;
 # --solutions--
 
 ```js
-var myVar = 87;
+let myVar = 87;
 myVar++;
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md
index 44dc5c4988c..700f84c2a76 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md
@@ -64,7 +64,7 @@ assert(testElse(10) === 'Bigger than 5');
 No debes cambiar el código por encima o por debajo de los comentarios especificados.
 
 ```js
-assert(/var result = "";/.test(code) && /return result;/.test(code));
+assert(/let result = "";/.test(code) && /return result;/.test(code));
 ```
 
 # --seed--
@@ -73,7 +73,7 @@ assert(/var result = "";/.test(code) && /return result;/.test(code));
 
 ```js
 function testElse(val) {
-  var result = "";
+  let result = "";
   // Only change code below this line
 
   if (val > 5) {
@@ -95,7 +95,7 @@ testElse(4);
 
 ```js
 function testElse(val) {
-  var result = "";
+  let result = "";
   if(val > 5) {
     result = "Bigger than 5";
   } else {
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md
index 4e42c0d59e6..0afa922388e 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md
@@ -12,8 +12,9 @@ dashedName: iterate-through-an-array-with-a-for-loop
 Una tarea común en JavaScript es iterar a través del contenido de un arreglo. Una forma de hacerlo es con un bucle `for`. Este código mostrará cada elemento del arreglo `arr` en la consola:
 
 ```js
-var arr = [10, 9, 8, 7, 6];
-for (var i = 0; i < arr.length; i++) {
+const arr = [10, 9, 8, 7, 6];
+
+for (let i = 0; i < arr.length; i++) {
    console.log(arr[i]);
 }
 ```
@@ -62,18 +63,19 @@ assert(!__helpers.removeWhiteSpace(code).match(/total[=+-]0*[1-9]+/gm));
 
 ```js
 // Setup
-var myArr = [ 2, 3, 4, 5, 6];
+const myArr = [2, 3, 4, 5, 6];
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myArr = [ 2, 3, 4, 5, 6];
-var total = 0;
+const myArr = [2, 3, 4, 5, 6];
+let total = 0;
 
-for (var i = 0; i < myArr.length; i++) {
+for (let i = 0; i < myArr.length; i++) {
   total += myArr[i];
 }
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md
index 1d3bb74e583..ec75b75adb2 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md
@@ -12,8 +12,9 @@ dashedName: iterate-with-javascript-do---while-loops
 El siguiente tipo de bucle que aprenderás se llama bucle `do...while`. Se llama bucle `do...while` porque primero hace (`do`) una pasada por el código dentro del bucle sin importar qué, y luego continua ejecutando el bucle mientras (`while`) la condición especificada sea verdadera (`true`).
 
 ```js
-var ourArray = [];
-var i = 0;
+const ourArray = [];
+let i = 0;
+
 do {
   ourArray.push(i);
   i++;
@@ -23,8 +24,9 @@ do {
 El ejemplo anterior se comporta de forma similar a otros tipos de bucles, siendo el arreglo resultante `[0, 1, 2, 3, 4]`. Sin embargo, lo que hace que el bucle `do...while` sea diferente a otros bucles es cómo se comporta cuando la condición falla en la primera verificación. Veamos esto en acción: Aquí puedes ver un bucle `while` que ejecutará el código una y otra vez siempre que `i < 5`:
 
 ```js
-var ourArray = []; 
-var i = 5;
+const ourArray = []; 
+let i = 5;
+
 while (i < 5) {
   ourArray.push(i);
   i++;
@@ -34,8 +36,9 @@ while (i < 5) {
 En este ejemplo, inicializamos el valor de `ourArray` a un arreglo vacío y el valor de `i` a 5. Cuando ejecutamos el bucle `while`, la condición se evalúa como `false` porque `i` no es inferior a 5, así que no ejecutamos el código dentro del bucle. El resultado es que `ourArray` terminará sin valores añadidos, y todavía se verá como `[]` una vez el código del ejemplo anterior haya terminado de ejecutarse. Ahora, dale un vistazo a un bucle `do...while`:
 
 ```js
-var ourArray = []; 
-var i = 5;
+const ourArray = []; 
+let i = 5;
+
 do {
   ourArray.push(i);
   i++;
@@ -80,8 +83,8 @@ if(typeof myArray !== "undefined"){(function(){return myArray;})();}
 
 ```js
 // Setup
-var myArray = [];
-var i = 10;
+const myArray = [];
+let i = 10;
 
 // Only change code below this line
 while (i < 5) {
@@ -93,8 +96,8 @@ while (i < 5) {
 # --solutions--
 
 ```js
-var myArray = [];
-var i = 10;
+const myArray = [];
+let i = 10;
 do {
   myArray.push(i);
   i++;
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md
index 1fef0ad88cd..3a21aa33866 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md
@@ -15,9 +15,10 @@ Esta es una función `myTest` con una variable local llamada `loc`.
 
 ```js
 function myTest() {
-  var loc = "foo";
+  const loc = "foo";
   console.log(loc);
 }
+
 myTest();
 console.log(loc);
 ```
@@ -38,6 +39,7 @@ El código no debe contener una variable global `myVar`.
 function declared() {
   myVar;
 }
+
 assert.throws(declared, ReferenceError);
 ```
 
@@ -57,7 +59,6 @@ assert(
 
 ```js
 function myLocalScope() {
-
   // Only change code below this line
 
   console.log('inside myLocalScope', myVar);
@@ -73,9 +74,8 @@ console.log('outside myLocalScope', myVar);
 
 ```js
 function myLocalScope() {
-
   // Only change code below this line
-  var myVar;
+  let myVar;
   console.log('inside myLocalScope', myVar);
 }
 myLocalScope();
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md
index 38378fca34f..98211251ea8 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md
@@ -16,10 +16,10 @@ Una forma fácil de añadir datos al final de un arreglo es a través de la func
 Ejemplos:
 
 ```js
-var arr1 = [1,2,3];
+const arr1 = [1, 2, 3];
 arr1.push(4);
 
-var arr2 = ["Stimpson", "J", "cat"];
+const arr2 = ["Stimpson", "J", "cat"];
 arr2.push(["happy", "joy"]);
 ```
 
@@ -64,14 +64,15 @@ assert(
 
 ```js
 // Setup
-var myArray = [["John", 23], ["cat", 2]];
+const myArray = [["John", 23], ["cat", 2]];
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myArray = [["John", 23], ["cat", 2]];
+const myArray = [["John", 23], ["cat", 2]];
 myArray.push(["dog",3]);
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md
index 1316f3c02f1..5404cd0fd0a 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md
@@ -14,7 +14,7 @@ A veces, es posible que desees almacenar datos en una <dfn>estructura de datos</
 Este es un ejemplo de una estructura de datos compleja:
 
 ```js
-var ourMusic = [
+const ourMusic = [
   {
     "artist": "Daft Punk",
     "title": "Homework",
@@ -135,7 +135,7 @@ myMusic.forEach(object => {
 ## --seed-contents--
 
 ```js
-var myMusic = [
+const myMusic = [
   {
     "artist": "Billy Joel",
     "title": "Piano Man",
@@ -153,7 +153,7 @@ var myMusic = [
 # --solutions--
 
 ```js
-var myMusic = [
+const myMusic = [
   {
     "artist": "Billy Joel",
     "title": "Piano Man",
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md
index 7b0be19c848..6c95d8050f3 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md
@@ -12,7 +12,7 @@ dashedName: multiple-identical-options-in-switch-statements
 Si la sentencia `break` es omitida en un caso (`case`) de una sentencia `switch`, las siguientes sentencias `case` serán ejecutadas hasta encontrar un `break`. Si tienes múltiples entradas con la misma salida, puedes representarlas en una sentencia `switch` como esta:
 
 ```js
-var result = "";
+let result = "";
 switch(val) {
   case 1:
   case 2:
@@ -109,7 +109,7 @@ assert(code.match(/case/g).length === 9);
 
 ```js
 function sequentialSizes(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
 
@@ -125,7 +125,7 @@ sequentialSizes(1);
 
 ```js
 function sequentialSizes(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case 1:
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md
index 7345e4d5e58..6682d8f7602 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md
@@ -42,11 +42,11 @@ assert(/\*/.test(code));
 ## --seed-contents--
 
 ```js
-var product = 2.0 * 0.0;
+const product = 2.0 * 0.0;
 ```
 
 # --solutions--
 
 ```js
-var product = 2.0 * 2.5;
+const product = 2.0 * 2.5;
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md
index 9365ddea99a..7dae3ad752c 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md
@@ -16,7 +16,7 @@ JavaScript utiliza el símbolo `*` para multiplicar dos números.
 **Ejemplo**
 
 ```js
-myVar = 13 * 13;
+const myVar = 13 * 13;
 ```
 
 `myVar` ahora tendrá el valor `169`.
@@ -50,11 +50,11 @@ assert(/\*/.test(code));
 ## --seed-contents--
 
 ```js
-var product = 8 * 0;
+const product = 8 * 0;
 ```
 
 # --solutions--
 
 ```js
-var product = 8 * 10;
+const product = 8 * 10;
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md
index d8af7d46f53..e026503ec3f 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md
@@ -12,7 +12,7 @@ dashedName: nest-one-array-within-another-array
 También puedes anidar arreglos dentro de otros arreglos, como a continuación:
 
 ```js
-[["Bulls", 23], ["White Sox", 45]]
+const teams = [["Bulls", 23], ["White Sox", 45]];
 ```
 
 Esto también es conocido como <dfn>arreglo multidimensional</dfn>.
@@ -41,11 +41,11 @@ if(typeof myArray !== "undefined"){(function(){return myArray;})();}
 
 ```js
 // Only change code below this line
-var myArray = [];
+const myArray = [];
 ```
 
 # --solutions--
 
 ```js
-var myArray = [[1,2,3]];
+const myArray = [[1, 2, 3]];
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md
index 7af20779f5b..2bf87be0282 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md
@@ -68,34 +68,33 @@ assert(lookUpProfile('Akira', 'address') === 'No such property');
 
 ```js
 // Setup
-var contacts = [
-    {
-        "firstName": "Akira",
-        "lastName": "Laine",
-        "number": "0543236543",
-        "likes": ["Pizza", "Coding", "Brownie Points"]
-    },
-    {
-        "firstName": "Harry",
-        "lastName": "Potter",
-        "number": "0994372684",
-        "likes": ["Hogwarts", "Magic", "Hagrid"]
-    },
-    {
-        "firstName": "Sherlock",
-        "lastName": "Holmes",
-        "number": "0487345643",
-        "likes": ["Intriguing Cases", "Violin"]
-    },
-    {
-        "firstName": "Kristian",
-        "lastName": "Vos",
-        "number": "unknown",
-        "likes": ["JavaScript", "Gaming", "Foxes"]
-    }
+const contacts = [
+  {
+    firstName: "Akira",
+    lastName: "Laine",
+    number: "0543236543",
+    likes: ["Pizza", "Coding", "Brownie Points"],
+  },
+  {
+    firstName: "Harry",
+    lastName: "Potter",
+    number: "0994372684",
+    likes: ["Hogwarts", "Magic", "Hagrid"],
+  },
+  {
+    firstName: "Sherlock",
+    lastName: "Holmes",
+    number: "0487345643",
+    likes: ["Intriguing Cases", "Violin"],
+  },
+  {
+    firstName: "Kristian",
+    lastName: "Vos",
+    number: "unknown",
+    likes: ["JavaScript", "Gaming", "Foxes"],
+  },
 ];
 
-
 function lookUpProfile(name, prop) {
   // Only change code below this line
 
@@ -108,44 +107,38 @@ lookUpProfile("Akira", "likes");
 # --solutions--
 
 ```js
-var contacts = [
-    {
-        "firstName": "Akira",
-        "lastName": "Laine",
-        "number": "0543236543",
-        "likes": ["Pizza", "Coding", "Brownie Points"]
-    },
-    {
-        "firstName": "Harry",
-        "lastName": "Potter",
-        "number": "0994372684",
-        "likes": ["Hogwarts", "Magic", "Hagrid"]
-    },
-    {
-        "firstName": "Sherlock",
-        "lastName": "Holmes",
-        "number": "0487345643",
-        "likes": ["Intriguing Cases", "Violin"]
-    },
-    {
-        "firstName": "Kristian",
-        "lastName": "Vos",
-        "number": "unknown",
-        "likes": ["JavaScript", "Gaming", "Foxes"]
-    },
+const contacts = [
+  {
+    firstName: "Akira",
+    lastName: "Laine",
+    number: "0543236543",
+    likes: ["Pizza", "Coding", "Brownie Points"],
+  },
+  {
+    firstName: "Harry",
+    lastName: "Potter",
+    number: "0994372684",
+    likes: ["Hogwarts", "Magic", "Hagrid"],
+  },
+  {
+    firstName: "Sherlock",
+    lastName: "Holmes",
+    number: "0487345643",
+    likes: ["Intriguing Cases", "Violin"],
+  },
+  {
+    firstName: "Kristian",
+    lastName: "Vos",
+    number: "unknown",
+    likes: ["JavaScript", "Gaming", "Foxes"],
+  },
 ];
-
-
-//Write your function in between these comments
-function lookUpProfile(name, prop){
-    for(var i in contacts){
-      if(contacts[i].firstName === name) {
-        return contacts[i][prop] || "No such property";
-      }
+function lookUpProfile(name, prop) {
+  for (let i in contacts) {
+    if (contacts[i].firstName === name) {
+      return contacts[i][prop] || "No such property";
     }
-   return "No such contact";
+  }
+  return "No such contact";
 }
-//Write your function in between these comments
-
-lookUpProfile("Akira", "likes");
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md
index 02eb073a9b8..5854d92ad44 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md
@@ -12,21 +12,21 @@ dashedName: quoting-strings-with-single-quotes
 Los valores de <dfn>cadena</dfn> en JavaScript pueden escribirse con comillas simples o dobles, siempre y cuando comiencen y terminen con el mismo tipo de comillas. A diferencia de otros lenguajes de programación, las comillas simples y dobles funcionan igual en JavaScript.
 
 ```js
-doubleQuoteStr = "This is a string"; 
-singleQuoteStr = 'This is also a string';
+const doubleQuoteStr = "This is a string"; 
+const singleQuoteStr = 'This is also a string';
 ```
 
 La razón por la que puedes querer usar un tipo de comilla sobre otro es si quieres usar ambos en una cadena. Esto puede suceder si quieres guardar una conversación en una cadena y tener la conversación entre comillas. Otro uso sería guardar una etiqueta `<a>` con varios atributos entre comillas, todo dentro de una cadena.
 
 ```js
-conversation = 'Finn exclaims to Jake, "Algebraic!"';
+const conversation = 'Finn exclaims to Jake, "Algebraic!"';
 ```
 
 Sin embargo, esto se convierte en un problema cuando es necesario utilizar las comillas externas dentro de ella. Recuerda, una cadena tiene el mismo tipo de comillas al principio y al final. Pero si tienes esa misma comilla en algún lugar del medio, la cadena se detendrá antes de tiempo y arrojará un error.
 
 ```js
-goodStr = 'Jake asks Finn, "Hey, let\'s go on an adventure?"'; 
-badStr = 'Finn responds, "Let's go!"';
+const goodStr = 'Jake asks Finn, "Hey, let\'s go on an adventure?"'; 
+const badStr = 'Finn responds, "Let's go!"';
 ```
 
 Aquí `badStr` arrojará un error.
@@ -71,11 +71,11 @@ assert(code.match(/"/g).length === 4 && code.match(/'/g).length === 2);
 ## --seed-contents--
 
 ```js
-var myStr = "<a href=\"http://www.example.com\" target=\"_blank\">Link</a>";
+const myStr = "<a href=\"http://www.example.com\" target=\"_blank\">Link</a>";
 ```
 
 # --solutions--
 
 ```js
-var myStr = '<a href="http://www.example.com" target="_blank">Link</a>';
+const myStr = '<a href="http://www.example.com" target="_blank">Link</a>';
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md
index 5849fa8fbe0..74d1e180a1a 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md
@@ -115,7 +115,7 @@ const _recordCollection = {
 
 ```js
 // Setup
-var recordCollection = {
+const recordCollection = {
   2548: {
     albumTitle: 'Slippery When Wet',
     artist: 'Bon Jovi',
@@ -146,7 +146,7 @@ updateRecords(recordCollection, 5439, 'artist', 'ABBA');
 # --solutions--
 
 ```js
-var recordCollection = {
+const recordCollection = {
   2548: {
     albumTitle: 'Slippery When Wet',
     artist: 'Bon Jovi',
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md
index 8974b3fd8b8..891a471e0c3 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md
@@ -14,9 +14,9 @@ La recursión es el concepto que una función puede expresarse en términos de s
 
 ```js
   function multiply(arr, n) {
-    var product = 1;
-    for (var i = 0; i < n; i++) {
-        product *= arr[i];
+    let product = 1;
+    for (let i = 0; i < n; i++) {
+      product *= arr[i];
     }
     return product;
   }
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md
index 1962d9e774e..93d1594bc9c 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md
@@ -108,7 +108,7 @@ assert(chainToSwitch(156) === '');
 
 ```js
 function chainToSwitch(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
   if (val === "bob") {
@@ -134,7 +134,7 @@ chainToSwitch(7);
 
 ```js
 function chainToSwitch(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case "bob":
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md
index d1f04efc870..6a3519ada76 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md
@@ -17,7 +17,8 @@ Podemos pasar valores a una función con <dfn>argumentos</dfn>. Puedes utilizar
 function plusThree(num) {
   return num + 3;
 }
-var answer = plusThree(5);
+
+const answer = plusThree(5);
 ```
 
 `answer` tiene el valor `8`.
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md
index 3a543cb78fe..50dbad3f081 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md
@@ -78,7 +78,7 @@ assert(code.match(/break/g).length > 2);
 
 ```js
 function caseInSwitch(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
 
@@ -94,7 +94,7 @@ caseInSwitch(1);
 
 ```js
 function caseInSwitch(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case 1:
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md
index 5ad68ad924c..b871e40ca09 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md
@@ -81,13 +81,13 @@ var hasNumber = false;
 ## --seed-contents--
 
 ```js
-var myList = [];
+const myList = [];
 ```
 
 # --solutions--
 
 ```js
-var myList = [
+const myList = [
   ["Candy", 10],
   ["Potatoes", 12],
   ["Eggs", 12],
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md
index f9cd3b33eaf..919821a26a0 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md
@@ -93,12 +93,10 @@ function nextInLine(arr, item) {
 
   return item;
   // Only change code above this line
-
-
 }
 
 // Setup
-var testArr = [1,2,3,4,5];
+const testArr = [1, 2, 3, 4, 5];
 
 // Display code
 console.log("Before: " + JSON.stringify(testArr));
@@ -109,7 +107,7 @@ console.log("After: " + JSON.stringify(testArr));
 # --solutions--
 
 ```js
-var testArr = [ 1,2,3,4,5];
+const testArr = [1, 2, 3, 4, 5];
 
 function nextInLine(arr, item) {
     arr.push(item);
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md
index a0a41794b30..b44ecfdbd65 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md
@@ -14,7 +14,7 @@ Con las variables de arreglos (`array`) de JavaScript, podemos almacenar varios
 Inicias una declaración de arreglo con un corchete de apertura, lo terminas con un corchete de cierre, y pones una coma entre cada entrada, de esta forma:
 
 ```js
-var sandwich = ["peanut butter", "jelly", "bread"]
+const sandwich = ["peanut butter", "jelly", "bread"];
 ```
 
 # --instructions--
@@ -53,11 +53,11 @@ assert(typeof myArray[1] !== 'undefined' && typeof myArray[1] == 'number');
 
 ```js
 // Only change code below this line
-var myArray = [];
+const myArray = [];
 ```
 
 # --solutions--
 
 ```js
-var myArray = ["The Answer", 42];
+const myArray = ["The Answer", 42];
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md
index bc9dbeea320..ee20d1e41b2 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md
@@ -16,7 +16,7 @@ JavaScript utiliza el símbolo `-` para restar.
 **Ejemplo**
 
 ```js
-myVar = 12 - 6;
+const myVar = 12 - 6;
 ```
 
 `myVar` tendrá el valor `6`.
@@ -49,11 +49,11 @@ assert(/difference=45-33;?/.test(__helpers.removeWhiteSpace(code)));
 ## --seed-contents--
 
 ```js
-var difference = 45 - 0;
+const difference = 45 - 0;
 ```
 
 # --solutions--
 
 ```js
-var difference = 45 - 33;
+const difference = 45 - 33;
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md
index 49d3dd9a5d0..43f63724a0c 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md
@@ -13,10 +13,11 @@ A veces es útil comprobar si existe o no la propiedad de un objeto dado. Podemo
 **Por ejemplo**
 
 ```js
-var myObj = {
+const myObj = {
   top: "hat",
   bottom: "pants"
 };
+
 myObj.hasOwnProperty("top");
 myObj.hasOwnProperty("middle");
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md
index a02754f7ce2..f2df8c4d51d 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md
@@ -14,14 +14,14 @@ En JavaScript, los valores de cadena (`String`) son <dfn>inmutables</dfn>, lo qu
 Por ejemplo, el siguiente código:
 
 ```js
-var myStr = "Bob";
+let myStr = "Bob";
 myStr[0] = "J";
 ```
 
 no puede cambiar el valor de `myStr` a `Job`, porque el contenido de `myStr` no puede ser alterado. Ten en cuenta que esto *no* significa que `myStr` no puede cambiarse, solo que los caracteres individuales de una <dfn>cadena literal</dfn> no pueden ser cambiados. La única forma de cambiar `myStr` sería asignarla con una nueva cadena, como esta:
 
 ```js
-var myStr = "Bob";
+let myStr = "Bob";
 myStr = "Job";
 ```
 
@@ -55,7 +55,7 @@ assert(/myStr = "Jello World"/.test(code));
 
 ```js
 // Setup
-var myStr = "Jello World";
+let myStr = "Jello World";
 
 // Only change code below this line
 myStr[0] = "H"; // Change this line
@@ -65,6 +65,6 @@ myStr[0] = "H"; // Change this line
 # --solutions--
 
 ```js
-var myStr = "Jello World";
+let myStr = "Jello World";
 myStr = "Hello World";
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md
index 28f7f63820c..9955a5dca93 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md
@@ -43,7 +43,6 @@ welcomeToBooleans();
 
 ```js
 function welcomeToBooleans() {
-
   // Only change code below this line
 
   return false; // Change this line
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md
index 38523e8d55f..927b0d5ddec 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md
@@ -14,10 +14,12 @@ Una función puede incluir la declaración de devolución (`return`) pero no tie
 **Ejemplo**
 
 ```js
-var sum = 0;
+let sum = 0;
+
 function addSum(num) {
   sum = sum + num;
 }
+
 addSum(3);
 ```
 
@@ -61,7 +63,7 @@ assert(
 
 ```js
 // Setup
-var sum = 0;
+let sum = 0;
 
 function addThree() {
   sum = sum + 3;
@@ -79,7 +81,7 @@ addFive();
 # --solutions--
 
 ```js
-var sum = 0;
+let sum = 0;
 
 function addThree() {
   sum = sum + 3;
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md
index 2785ee3dbf4..b72ddf979cc 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md
@@ -14,7 +14,7 @@ Después de haber creado un objeto de JavaScript, puedes actualizar sus propieda
 Por ejemplo, veamos `ourDog`:
 
 ```js
-var ourDog = {
+const ourDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
@@ -54,7 +54,7 @@ assert(/"name": "Coder"/.test(code));
 
 ```js
 // Setup
-var myDog = {
+const myDog = {
   "name": "Coder",
   "legs": 4,
   "tails": 1,
@@ -62,12 +62,13 @@ var myDog = {
 };
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Coder",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md
index 5218cfebd93..7e5ef9881d1 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md
@@ -16,8 +16,8 @@ Recuerda que las computadoras empiezan a contar desde `0`, así que el primer ca
 Ejemplo:
 
 ```js
-var firstName = "Ada";
-var secondLetterOfFirstName = firstName[1];
+const firstName = "Ada";
+const secondLetterOfFirstName = firstName[1];
 ```
 
 `secondLetterOfFirstName` tendrá una cadena con valor `d`.
@@ -54,15 +54,15 @@ assert(code.match(/thirdLetterOfLastName\s*?=\s*?lastName\[.*?\]/));
 
 ```js
 // Setup
-var lastName = "Lovelace";
+const lastName = "Lovelace";
 
 // Only change code below this line
-var thirdLetterOfLastName = lastName; // Change this line
+const thirdLetterOfLastName = lastName; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var lastName = "Lovelace";
-var thirdLetterOfLastName = lastName[2];
+const lastName = "Lovelace";
+const thirdLetterOfLastName = lastName[2];
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md
index 40a5b6290a3..dc86e0fd785 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md
@@ -73,7 +73,7 @@ function rangeOfNumbers(startNum, endNum) {
   if (endNum - startNum === 0) {
     return [startNum];
   } else {
-    var numbers = rangeOfNumbers(startNum, endNum - 1);
+    const numbers = rangeOfNumbers(startNum, endNum - 1);
     numbers.push(endNum);
     return numbers;
   }
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md
index aa0a75306cb..d90574d1e9a 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md
@@ -20,7 +20,7 @@ parseInt(string, radix);
 Y aquí hay un ejemplo:
 
 ```js
-var a = parseInt("11", 2);
+const a = parseInt("11", 2);
 ```
 
 La variable radix indica que `11` está en el sistema binario, o base 2. Este ejemplo convierte la cadena `11` a un entero `3`.
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md
index 4f1936b4803..0af05486470 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md
@@ -12,7 +12,7 @@ dashedName: use-the-parseint-function
 La función `parseInt()` analiza una cadena y devuelve un entero. A continuación, te presentamos un ejemplo:
 
 ```js
-var a = parseInt("007");
+const a = parseInt("007");
 ```
 
 La función anterior convierte la cadena `007` al entero `7`. Si el primer carácter de la cadena no puede ser convertido en un número, entonces devuelve `NaN`.
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md
index b5b5de152b0..406b1506643 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md
@@ -14,7 +14,7 @@ Los objetos pueden ser considerados como un almacenamiento clave/valor, como un
 Aquí hay un ejemplo de una simple búsqueda de alfabeto inverso:
 
 ```js
-var alpha = {
+const alpha = {
   1:"Z",
   2:"Y",
   3:"X",
@@ -24,10 +24,11 @@ var alpha = {
   25:"B",
   26:"A"
 };
+
 alpha[2];
 alpha[24];
 
-var value = 2;
+const value = 2;
 alpha[value];
 ```
 
@@ -102,7 +103,7 @@ assert(
 ```js
 // Setup
 function phoneticLookup(val) {
-  var result = "";
+  let result = "";
 
   // Only change code below this line
   switch(val) {
@@ -136,9 +137,9 @@ phoneticLookup("charlie");
 
 ```js
 function phoneticLookup(val) {
-  var result = "";
+  let result = "";
 
-  var lookup = {
+  const lookup = {
     alpha: "Adams",
     bravo: "Boston",
     charlie: "Chicago",
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md
index 6eae3b7f021..79b3ba88261 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md
@@ -16,7 +16,7 @@ En un juego de "Mad Libs", se te proporcionan oraciones con algunas palabras fal
 Considera esta oración: It was really **\_\_\_\_**, and we **\_\_\_\_** ourselves **\_\_\_\_**. Esta oración tiene tres piezas faltantes: un adjetivo, un verbo y un adverbio, y podemos añadir palabras de nuestra elección para completarla. A continuación, podemos asignar la oración completa a una variable de la siguiente manera:
 
 ```js
-var sentence = "It was really " + "hot" + ", and we " + "laughed" + " ourselves " + "silly" + ".";
+const sentence = "It was really " + "hot" + ", and we " + "laughed" + " ourselves " + "silly" + ".";
 ```
 
 # --instructions--
@@ -84,24 +84,24 @@ const removeAssignments = str => str
 ## --seed-contents--
 
 ```js
-var myNoun = "dog";
-var myAdjective = "big";
-var myVerb = "ran";
-var myAdverb = "quickly";
+const myNoun = "dog";
+const myAdjective = "big";
+const myVerb = "ran";
+const myAdverb = "quickly";
 
 // Only change code below this line
-var wordBlanks = ""; // Change this line
+const wordBlanks = ""; // Change this line
 // Only change code above this line
 ```
 
 # --solutions--
 
 ```js
-var myNoun = "dog";
-var myAdjective = "big";
-var myVerb = "ran";
-var myAdverb = "quickly";
+const myNoun = "dog";
+const myAdjective = "big";
+const myVerb = "ran";
+const myAdverb = "quickly";
 
-var wordBlanks = "Once there was a " + myNoun + " which was very " + myAdjective + ". ";
+let wordBlanks = "Once there was a " + myNoun + " which was very " + myAdjective + ". ";
 wordBlanks += "It " + myVerb + " " + myAdverb + " around the yard.";
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md
index 2369749346c..1310e076931 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md
@@ -13,7 +13,7 @@ La programación funcional consiste en crear y utilizar funciones no mutantes.
 El último desafío introdujo el método `concat` como una forma de combinar arreglos en uno nuevo sin mutar los arreglos originales. Compara `concat` con el método `push`. `push` añade un elemento al final del arreglo desde el que se llama, lo cual muta ese arreglo. Aquí hay un ejemplo:
 
 ```js
-var arr = [1, 2, 3];
+const arr = [1, 2, 3];
 arr.push([4, 5, 6]);
 ```
 
@@ -71,8 +71,9 @@ function nonMutatingPush(original, newItem) {
 
   // Only change code above this line
 }
-var first = [1, 2, 3];
-var second = [4, 5];
+
+const first = [1, 2, 3];
+const second = [4, 5];
 nonMutatingPush(first, second);
 ```
 
@@ -82,7 +83,6 @@ nonMutatingPush(first, second);
 function nonMutatingPush(original, newItem) {
   return original.concat(newItem);
 }
-var first = [1, 2, 3];
-var second = [4, 5];
-nonMutatingPush(first, second);
+const first = [1, 2, 3];
+const second = [4, 5];
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md
index b2d3672f337..3afd2aaf536 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md
@@ -77,7 +77,6 @@ function urlSlug(title) {
 # --solutions--
 
 ```js
-// Only change code below this line
 function urlSlug(title) {
   return title.trim().split(/\s+/).join("-").toLowerCase();
 }
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md
index 69d19937ccd..fd864b7935b 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md
@@ -57,9 +57,9 @@ La función `incrementer` debe devolver un valor basado en el valor de la variab
 
 ```js
 // The global variable
-var fixedValue = 4;
+let fixedValue = 4;
 
-function incrementer () {
+function incrementer() {
   // Only change code below this line
 
 
@@ -70,7 +70,7 @@ function incrementer () {
 # --solutions--
 
 ```js
-var fixedValue = 4
+let fixedValue = 4
 
 function incrementer() {
   return fixedValue + 1
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md
index 4212cdfa64b..259cb36d583 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md
@@ -13,8 +13,8 @@ El método `join` se utiliza para unir los elementos de un arreglo creando una c
 Aquí hay un ejemplo:
 
 ```js
-var arr = ["Hello", "World"];
-var str = arr.join(" ");
+const arr = ["Hello", "World"];
+const str = arr.join(" ");
 ```
 
 `str` tendrá una cadena con valor `Hello World`.
@@ -76,6 +76,7 @@ function sentensify(str) {
 
   // Only change code above this line
 }
+
 sentensify("May-the-force-be-with-you");
 ```
 
@@ -83,8 +84,6 @@ sentensify("May-the-force-be-with-you");
 
 ```js
 function sentensify(str) {
-  // Only change code below this line
   return str.split(/\W/).join(' ');
-  // Only change code above this line
 }
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md
index 5e37c124d5b..093ca3c21bd 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md
@@ -60,8 +60,9 @@ function nonMutatingConcat(original, attach) {
 
   // Only change code above this line
 }
-var first = [1, 2, 3];
-var second = [4, 5];
+
+const first = [1, 2, 3];
+const second = [4, 5];
 nonMutatingConcat(first, second);
 ```
 
@@ -69,11 +70,8 @@ nonMutatingConcat(first, second);
 
 ```js
 function nonMutatingConcat(original, attach) {
-  // Only change code below this line
   return original.concat(attach);
-  // Only change code above this line
 }
-var first = [1, 2, 3];
-var second = [4, 5];
-nonMutatingConcat(first, second);
+const first = [1, 2, 3];
+const second = [4, 5];
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md
index a40f53303ab..949663b2e80 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md
@@ -38,17 +38,17 @@ assert(!code.match(/\.?[\s\S]*?map/g));
 
 ```js
 // The global variable
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myMap = function(callback) {
-  var newArray = [];
+  const newArray = [];
   // Only change code below this line
 
   // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myMap(function(item) {
+const new_s = s.myMap(function(item) {
   return item * 2;
 });
 ```
@@ -56,20 +56,17 @@ var new_s = s.myMap(function(item) {
 # --solutions--
 
 ```js
-// the global Array
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myMap = function(callback) {
-  var newArray = [];
-  // Only change code below this line
-  for (var elem of this) {
+  const newArray = [];
+  for (const elem of this) {
     newArray.push(callback(elem));
   }
-  // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myMap(function(item) {
+const new_s = s.myMap(function(item) {
   return item * 2;
 });
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md
index ebe22f322db..4d8ff981d3b 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md
@@ -34,16 +34,16 @@ assert(!code.match(/\.?[\s\S]*?filter/g));
 
 ```js
 // The global variable
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myFilter = function(callback) {
   // Only change code below this line
-  var newArray = [];
+  const newArray = [];
   // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myFilter(function(item) {
+const new_s = s.myFilter(function(item) {
   return item % 2 === 1;
 });
 ```
@@ -51,20 +51,17 @@ var new_s = s.myFilter(function(item) {
 # --solutions--
 
 ```js
-// the global Array
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myFilter = function(callback) {
-  var newArray = [];
-  // Only change code below this line
+  const newArray = [];
   for (let i = 0; i < this.length; i++) {
     if (callback(this[i])) newArray.push(this[i]);
   }
-  // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myFilter(function(item) {
+const new_s = s.myFilter(function(item) {
   return item % 2 === 1;
 });
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md
index 4b0ae1f192d..16f2d4b5884 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md
@@ -35,7 +35,7 @@ curried(1)(2)
 Esto es útil en tu programa si no puedes proporcionar todos los argumentos a una función al mismo tiempo. Puedes guardar la llamada a cada función dentro de una variable, la cual mantendrá la referencia de la función devuelta que toma el siguiente argumento cuando este disponible. Aquí hay un ejemplo utilizando la función currificada del ejemplo anterior:
 
 ```js
-var funcForY = curried(1);
+const funcForY = curried(1);
 console.log(funcForY(2)); // 3
 ```
 
@@ -45,7 +45,8 @@ Similarmente, <dfn>la aplicación de una función parcial</dfn> puede describirs
 function impartial(x, y, z) {
   return x + y + z;
 }
-var partialFn = impartial.bind(this, 1, 2);
+
+const partialFn = impartial.bind(this, 1, 2);
 partialFn(10); // 13
 ```
 
@@ -90,6 +91,7 @@ function add(x) {
 
   // Only change code above this line
 }
+
 add(10)(20)(30);
 ```
 
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md
index e0a87646aa6..1cc861e9418 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md
@@ -53,10 +53,10 @@ assert(__newValue === 5);
 
 ```js
 // The global variable
-var fixedValue = 4;
+let fixedValue = 4;
 
 // Only change code below this line
-function incrementer () {
+function incrementer() {
 
 
   // Only change code above this line
@@ -66,15 +66,9 @@ function incrementer () {
 # --solutions--
 
 ```js
-// The global variable
-var fixedValue = 4;
+let fixedValue = 4;
 
-// Only change code below this line
-function incrementer (fixedValue) {
+function incrementer(fixedValue) {
   return fixedValue + 1;
-
-  // Only change code above this line
 }
-
-
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md
index fe201c8f62e..188c50d7a4f 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md
@@ -11,7 +11,7 @@ dashedName: remove-elements-from-an-array-using-slice-instead-of-splice
 Un patrón común al trabajar con arreglos es cuando deseas eliminar elementos y conservar el resto del arreglo. JavaScript ofrece el método `splice` para esto, que toma argumentos para el índice de dónde comenzar a eliminar elementos, luego la cantidad de elementos para eliminar. Si no se proporciona el segundo argumento, el valor predeterminado es eliminar elementos hasta el final. Sin embargo, el método `splice` muta el arreglo original en el que se llama. Por ejemplo:
 
 ```js
-var cities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
+const cities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
 cities.splice(3, 1);
 ```
 
@@ -69,7 +69,8 @@ function nonMutatingSplice(cities) {
 
   // Only change code above this line
 }
-var inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
+
+const inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
 nonMutatingSplice(inputCities);
 ```
 
@@ -77,10 +78,7 @@ nonMutatingSplice(inputCities);
 
 ```js
 function nonMutatingSplice(cities) {
-  // Only change code below this line
   return cities.slice(0,3);
-  // Only change code above this line
 }
-var inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
-nonMutatingSplice(inputCities);
+const inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md
index a55fb82f7bf..14466e332d3 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md
@@ -68,24 +68,23 @@ assert(JSON.stringify(nonMutatingSort([140000, 104, 99])) ===
 ## --seed-contents--
 
 ```js
-var globalArray = [5, 6, 3, 2, 9];
+const globalArray = [5, 6, 3, 2, 9];
+
 function nonMutatingSort(arr) {
   // Only change code below this line
 
 
   // Only change code above this line
 }
+
 nonMutatingSort(globalArray);
 ```
 
 # --solutions--
 
 ```js
-var globalArray = [5, 6, 3, 2, 9];
+const globalArray = [5, 6, 3, 2, 9];
 function nonMutatingSort(arr) {
-  // Only change code below this line
   return [].concat(arr).sort((a,b) => a-b);
-  // Only change code above this line
 }
-nonMutatingSort(globalArray);
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md
index ac5c9b90eb5..c64fccc1623 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md
@@ -13,8 +13,8 @@ El método `slice` devuelve una copia de ciertos elementos de un arreglo. Puede
 Por ejemplo:
 
 ```js
-var arr = ["Cat", "Dog", "Tiger", "Zebra"];
-var newArray = arr.slice(1, 3);
+const arr = ["Cat", "Dog", "Tiger", "Zebra"];
+const newArray = arr.slice(1, 3);
 ```
 
 `newArray` tendría el valor de `["Dog", "Tiger"]`.
@@ -78,7 +78,8 @@ function sliceArray(anim, beginSlice, endSlice) {
 
   // Only change code above this line
 }
-var inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
+
+const inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
 sliceArray(inputAnim, 1, 3);
 ```
 
@@ -86,10 +87,7 @@ sliceArray(inputAnim, 1, 3);
 
 ```js
 function sliceArray(anim, beginSlice, endSlice) {
-  // Only change code below this line
-  return anim.slice(beginSlice, endSlice)
-  // Only change code above this line
+  return anim.slice(beginSlice, endSlice);
 }
-var inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
-sliceArray(inputAnim, 1, 3);
+const inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md
index 00319a5f380..169a9c8a3dd 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md
@@ -18,6 +18,7 @@ function ascendingOrder(arr) {
     return a - b;
   });
 }
+
 ascendingOrder([1, 5, 2, 3, 4]);
 ```
 
@@ -29,6 +30,7 @@ function reverseAlpha(arr) {
     return a === b ? 0 : a < b ? 1 : -1;
   });
 }
+
 reverseAlpha(['l', 'h', 'z', 'b', 's']);
 ```
 
@@ -86,6 +88,7 @@ function alphabeticalOrder(arr) {
   return arr
   // Only change code above this line
 }
+
 alphabeticalOrder(["a", "d", "c", "a", "z", "g"]);
 ```
 
@@ -93,9 +96,6 @@ alphabeticalOrder(["a", "d", "c", "a", "z", "g"]);
 
 ```js
 function alphabeticalOrder(arr) {
-  // Only change code below this line
   return arr.sort();
-  // Only change code above this line
 }
-alphabeticalOrder(["a", "d", "c", "a", "z", "g"]);
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md
index 3b0a35f278c..c701217f92f 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md
@@ -13,11 +13,11 @@ El método `split` divide una cadena en un arreglo de cadenas. Se necesita un ar
 Aquí hay dos ejemplos que dividen una cadena por espacios, luego otra por dígitos utilizando una expresión regular:
 
 ```js
-var str = "Hello World";
-var bySpace = str.split(" ");
+const str = "Hello World";
+const bySpace = str.split(" ");
 
-var otherString = "How9are7you2today";
-var byDigits = otherString.split(/\d/);
+const otherString = "How9are7you2today";
+const byDigits = otherString.split(/\d/);
 ```
 
 `bySpace` tendrá el valor `["Hello", "World"]` y `byDigits` tendrá el valor `["How", "are", "you", "today"]`.
@@ -74,6 +74,7 @@ function splitify(str) {
 
   // Only change code above this line
 }
+
 splitify("Hello World,I-am code");
 ```
 
@@ -81,8 +82,6 @@ splitify("Hello World,I-am code");
 
 ```js
 function splitify(str) {
-  // Only change code below this line
   return str.split(/\W/);
-  // Only change code above this line
 }
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md
index 218998d8581..0db9abe2e8e 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md
@@ -59,29 +59,29 @@ assert.deepEqual(finalTabs.tabs, [
 
 ```js
 // tabs is an array of titles of each site open within the window
-var Window = function(tabs) {
+const Window = function(tabs) {
   this.tabs = tabs; // We keep a record of the array inside the object
 };
 
 // When you join two windows into one window
-Window.prototype.join = function (otherWindow) {
+Window.prototype.join = function(otherWindow) {
   this.tabs = this.tabs.concat(otherWindow.tabs);
   return this;
 };
 
 // When you open a new tab at the end
-Window.prototype.tabOpen = function (tab) {
+Window.prototype.tabOpen = function(tab) {
   this.tabs.push('new tab'); // Let's open a new tab for now
   return this;
 };
 
 // When you close a tab
-Window.prototype.tabClose = function (index) {
+Window.prototype.tabClose = function(index) {
 
   // Only change code below this line
 
-  var tabsBeforeIndex = this.tabs.splice(0, index); // Get the tabs before the tab
-  var tabsAfterIndex = this.tabs.splice(index + 1); // Get the tabs after the tab
+  const tabsBeforeIndex = this.tabs.splice(0, index); // Get the tabs before the tab
+  const tabsAfterIndex = this.tabs.splice(index + 1); // Get the tabs after the tab
 
   this.tabs = tabsBeforeIndex.concat(tabsAfterIndex); // Join them together
 
@@ -91,12 +91,12 @@ Window.prototype.tabClose = function (index) {
  };
 
 // Let's create three browser windows
-var workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']); // Your mailbox, drive, and other work sites
-var socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']); // Social sites
-var videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']); // Entertainment sites
+const workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']); // Your mailbox, drive, and other work sites
+const socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']); // Social sites
+const videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']); // Entertainment sites
 
 // Now perform the tab opening, closing, and other operations
-var finalTabs = socialWindow
+const finalTabs = socialWindow
   .tabOpen() // Open a new tab for cat memes
   .join(videoWindow.tabClose(2)) // Close third tab in video window, and join
   .join(workWindow.tabClose(1).tabOpen());
@@ -106,40 +106,34 @@ console.log(finalTabs.tabs);
 # --solutions--
 
 ```js
-// tabs is an array of titles of each site open within the window
-var Window = function(tabs) {
-  this.tabs = tabs; // We keep a record of the array inside the object
+const Window = function(tabs) {
+  this.tabs = tabs;
 };
 
-// When you join two windows into one window
-Window.prototype.join = function (otherWindow) {
+Window.prototype.join = function(otherWindow) {
   this.tabs = this.tabs.concat(otherWindow.tabs);
   return this;
 };
 
-// When you open a new tab at the end
-Window.prototype.tabOpen = function (tab) {
-  this.tabs.push('new tab'); // Let's open a new tab for now
+Window.prototype.tabOpen = function(tab) {
+  this.tabs.push('new tab');
   return this;
 };
 
-// When you close a tab
-Window.prototype.tabClose = function (index) {
-  var tabsBeforeIndex = this.tabs.slice(0, index); // Get the tabs before the tab
-  var tabsAfterIndex = this.tabs.slice(index + 1); // Get the tabs after the tab
+Window.prototype.tabClose = function(index) {
+  const tabsBeforeIndex = this.tabs.slice(0, index);
+  const tabsAfterIndex = this.tabs.slice(index + 1);
 
-  this.tabs = tabsBeforeIndex.concat(tabsAfterIndex); // Join them together
+  this.tabs = tabsBeforeIndex.concat(tabsAfterIndex);
   return this;
  };
 
-// Let's create three browser windows
-var workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']); // Your mailbox, drive, and other work sites
-var socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']); // Social sites
-var videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']); //  Entertainment sites
+const workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']);
+const socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']);
+const videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']);
 
-// Now perform the tab opening, closing, and other operations
-var finalTabs = socialWindow
-  .tabOpen() // Open a new tab for cat memes
-  .join(videoWindow.tabClose(2)) // Close third tab in video window, and join
+const finalTabs = socialWindow
+  .tabOpen()
+  .join(videoWindow.tabClose(2))
   .join(workWindow.tabClose(1).tabOpen());
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md
index 7e746cd33c9..a4bbb2bd692 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md
@@ -13,7 +13,8 @@ El método `every` funciona con arreglos para comprobar si *every element* pasa
 Por ejemplo, el siguiente código comprobaría si cada elemento en el arreglo `numbers` es menor a 10:
 
 ```js
-var numbers = [1, 5, 8, 0, 10, 11];
+const numbers = [1, 5, 8, 0, 10, 11];
+
 numbers.every(function(currentValue) {
   return currentValue < 10;
 });
@@ -62,6 +63,7 @@ function checkPositive(arr) {
 
   // Only change code above this line
 }
+
 checkPositive([1, 2, 3, -4, 5]);
 ```
 
@@ -69,9 +71,6 @@ checkPositive([1, 2, 3, -4, 5]);
 
 ```js
 function checkPositive(arr) {
-  // Only change code below this line
   return arr.every(num => num > 0);
-  // Only change code above this line
 }
-checkPositive([1, 2, 3, -4, 5]);
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md
index 4e52ed1165c..f3d3aac7bcd 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md
@@ -93,7 +93,7 @@ assert(getRating(watchList.filter((_, i) => i < 1 || i > 2)) === 8.55);
 
 ```js
 // The global variable
-var watchList = [
+const watchList = [
   {
     "Title": "Inception",
     "Year": "2010",
@@ -206,22 +206,22 @@ var watchList = [
   }
 ];
 
-function getRating(watchList){
+function getRating(watchList) {
   // Only change code below this line
-  var averageRating;
+  let averageRating;
 
 
   // Only change code above this line
   return averageRating;
 }
+
 console.log(getRating(watchList));
 ```
 
 # --solutions--
 
 ```js
-// The global variable
-var watchList = [
+const watchList = [
   {
     "Title": "Inception",
     "Year": "2010",
@@ -334,8 +334,8 @@ var watchList = [
   }
 ];
 
-function getRating(watchList){
-  var averageRating;
+function getRating(watchList) {
+  let averageRating;
   const rating = watchList
     .filter(obj => obj.Director === "Christopher Nolan")
     .map(obj => Number(obj.imdbRating));
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md
index efeffa6c6c7..3673e4b4d53 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md
@@ -13,7 +13,8 @@ El método `some` funciona con arreglos para comprobar si *algún* elemento pasa
 Por ejemplo, el siguiente código comprobará si algún elemento en el arreglo `numbers` es menor que 10:
 
 ```js
-var numbers = [10, 50, 8, 220, 110, 11];
+const numbers = [10, 50, 8, 220, 110, 11];
+
 numbers.some(function(currentValue) {
   return currentValue < 10;
 });
@@ -62,6 +63,7 @@ function checkPositive(arr) {
 
   // Only change code above this line
 }
+
 checkPositive([1, 2, 3, -4, 5]);
 ```
 
@@ -69,9 +71,6 @@ checkPositive([1, 2, 3, -4, 5]);
 
 ```js
 function checkPositive(arr) {
-  // Only change code below this line
   return arr.some(elem => elem > 0);
-  // Only change code above this line
 }
-checkPositive([1, 2, 3, -4, 5]);
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md
index 056817c90c3..f3a462f1b79 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md
@@ -157,7 +157,7 @@ assert(diffArray([1, 'calf', 3, 'piglet'], [7, 'filly']).length === 6);
 
 ```js
 function diffArray(arr1, arr2) {
-  var newArr = [];
+  const newArr = [];
   return newArr;
 }
 
@@ -168,13 +168,12 @@ diffArray([1, 2, 3, 5], [1, 2, 3, 4, 5]);
 
 ```js
 function diffArray(arr1, arr2) {
-  var newArr = [];
-  var h1 = Object.create(null);
+  const newArr = [];
+  const h1 = Object.create(null);
   arr1.forEach(function(e) {
     h1[e] = e;
   });
-
-  var h2 = Object.create(null);
+  const h2 = Object.create(null);
   arr2.forEach(function(e) {
     h2[e] = e;
   });
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md
index 1f829d2b212..5c477dd5f88 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md
@@ -148,7 +148,7 @@ if(bob){
 ## --seed-contents--
 
 ```js
-var Person = function(firstAndLast) {
+const Person = function(firstAndLast) {
   // Only change code below this line
   // Complete the method below and implement the others similarly
   this.getFullName = function() {
@@ -157,16 +157,16 @@ var Person = function(firstAndLast) {
   return firstAndLast;
 };
 
-var bob = new Person('Bob Ross');
+const bob = new Person('Bob Ross');
 bob.getFullName();
 ```
 
 # --solutions--
 
 ```js
-var Person = function(firstAndLast) {
+const Person = function(firstAndLast) {
 
-  var firstName, lastName;
+  let firstName, lastName;
 
   function updateName(str) {
     firstName = str.split(" ")[0];
@@ -201,6 +201,6 @@ var Person = function(firstAndLast) {
   };
 };
 
-var bob = new Person('Bob Ross');
+const bob = new Person('Bob Ross');
 bob.getFullName();
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md
index fb35ce9597d..d6dd3dd0eca 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md
@@ -51,8 +51,8 @@ assert.deepEqual(
 
 ```js
 function orbitalPeriod(arr) {
-  var GM = 398600.4418;
-  var earthRadius = 6367.4447;
+  const GM = 398600.4418;
+  const earthRadius = 6367.4447;
   return arr;
 }
 
@@ -63,9 +63,9 @@ orbitalPeriod([{name : "sputnik", avgAlt : 35873.5553}]);
 
 ```js
 function orbitalPeriod(arr) {
-  var GM = 398600.4418;
-  var earthRadius = 6367.4447;
-  var TAU = 2 * Math.PI;
+  const GM = 398600.4418;
+  const earthRadius = 6367.4447;
+  const TAU = 2 * Math.PI;
   return arr.map(function(obj) {
     return {
       name: obj.name,
@@ -73,6 +73,4 @@ function orbitalPeriod(arr) {
     };
   });
 }
-
-orbitalPeriod([{name : "sputkin", avgAlt : 35873.5553}]);
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md
index f4086865314..e139bc8c50e 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md
@@ -61,7 +61,6 @@ function smallestCommons(arr) {
   return arr;
 }
 
-
 smallestCommons([1,5]);
 ```
 
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md
index 94aa8c67ca2..40c02fa0622 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md
@@ -103,7 +103,7 @@ assert.deepEqual(
 
 ```js
 function whatIsInAName(collection, source) {
-  var arr = [];
+  const arr = [];
   // Only change code below this line
 
 
@@ -118,8 +118,8 @@ whatIsInAName([{ first: "Romeo", last: "Montague" }, { first: "Mercutio", last:
 
 ```js
 function whatIsInAName(collection, source) {
-  var arr = [];
-  var keys = Object.keys(source);
+  const arr = [];
+  const keys = Object.keys(source);
   collection.forEach(function(e) {
     if(keys.every(function(key) {return e[key] === source[key];})) {
       arr.push(e);
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md
index cf8a206db7a..06bd0ee5bbe 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md
@@ -51,7 +51,6 @@ assert(
 
 ```js
 function rot13(str) {
-
   return str;
 }
 
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md
index 0ed764ff53e..252b036d14d 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md
@@ -186,7 +186,7 @@ assert.deepEqual(
 
 ```js
 function checkCashRegister(price, cash, cid) {
-  var change;
+  let change;
   return change;
 }
 
@@ -196,54 +196,57 @@ checkCashRegister(19.5, 20, [["PENNY", 1.01], ["NICKEL", 2.05], ["DIME", 3.1], [
 # --solutions--
 
 ```js
-var denom = [
-    { name: 'ONE HUNDRED', val: 100},
-    { name: 'TWENTY', val: 20},
-    { name: 'TEN', val: 10},
-    { name: 'FIVE', val: 5},
-    { name: 'ONE', val: 1},
-    { name: 'QUARTER', val: 0.25},
-    { name: 'DIME', val: 0.1},
-    { name: 'NICKEL', val: 0.05},
-    { name: 'PENNY', val: 0.01}
+const denom = [
+  { name: "ONE HUNDRED", val: 100 },
+  { name: "TWENTY", val: 20 },
+  { name: "TEN", val: 10 },
+  { name: "FIVE", val: 5 },
+  { name: "ONE", val: 1 },
+  { name: "QUARTER", val: 0.25 },
+  { name: "DIME", val: 0.1 },
+  { name: "NICKEL", val: 0.05 },
+  { name: "PENNY", val: 0.01 },
 ];
 
 function checkCashRegister(price, cash, cid) {
- var output = {status: null, change: []};
- var change = cash - price;
- var register = cid.reduce(function(acc, curr) {
- acc.total += curr[1];
- acc[curr[0]] = curr[1];
- return acc;
- }, {total: 0});
- if(register.total === change) {
- output.status = 'CLOSED';
- output.change = cid;
- return output;
- }
- if(register.total < change) {
- output.status = 'INSUFFICIENT_FUNDS';
- return output;
- }
- var change_arr = denom.reduce(function(acc, curr) {
- var value = 0;
- while(register[curr.name] > 0 && change >= curr.val) {
- change -= curr.val;
- register[curr.name] -= curr.val;
- value += curr.val;
- change = Math.round(change * 100) / 100;
- }
- if(value > 0) {
- acc.push([ curr.name, value ]);
- }
- return acc;
- }, []);
- if(change_arr.length < 1 || change > 0) {
- output.status = 'INSUFFICIENT_FUNDS';
- return output;
- }
- output.status = 'OPEN';
- output.change = change_arr;
- return output;
+  const output = { status: null, change: [] };
+  let change = cash - price;
+  const register = cid.reduce(
+    function (acc, curr) {
+      acc.total += curr[1];
+      acc[curr[0]] = curr[1];
+      return acc;
+    },
+    { total: 0 }
+  );
+  if (register.total === change) {
+    output.status = "CLOSED";
+    output.change = cid;
+    return output;
+  }
+  if (register.total < change) {
+    output.status = "INSUFFICIENT_FUNDS";
+    return output;
+  }
+  const change_arr = denom.reduce(function (acc, curr) {
+    let value = 0;
+    while (register[curr.name] > 0 && change >= curr.val) {
+      change -= curr.val;
+      register[curr.name] -= curr.val;
+      value += curr.val;
+      change = Math.round(change * 100) / 100;
+    }
+    if (value > 0) {
+      acc.push([curr.name, value]);
+    }
+    return acc;
+  }, []);
+  if (change_arr.length < 1 || change > 0) {
+    output.status = "INSUFFICIENT_FUNDS";
+    return output;
+  }
+  output.status = "OPEN";
+  output.change = change_arr;
+  return output;
 }
 ```
diff --git a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md
index 21389cd2392..d2ddb307be0 100644
--- a/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md
+++ b/curriculum/challenges/espanol/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md
@@ -107,8 +107,6 @@ function palindrome(str) {
   return true;
 }
 
-
-
 palindrome("eye");
 ```
 
diff --git a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/chain-middleware-to-create-a-time-server.md b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/chain-middleware-to-create-a-time-server.md
index d68ab003f34..4f93504b335 100644
--- a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/chain-middleware-to-create-a-time-server.md
+++ b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/chain-middleware-to-create-a-time-server.md
@@ -1,6 +1,6 @@
 ---
 id: 587d7fb1367417b2b2512bf4
-title: Chain Middleware to Create a Time Server
+title: Encadenando Middlewares para crear un servidor horario
 challengeType: 2
 forumTopicId: 301510
 dashedName: chain-middleware-to-create-a-time-server
@@ -8,9 +8,9 @@ dashedName: chain-middleware-to-create-a-time-server
 
 # --description--
 
-Middleware can be mounted at a specific route using `app.METHOD(path, middlewareFunction)`. Middleware can also be chained inside route definition.
+Un middleware se puede montar en una ruta especifica usando `app.METHOD(path, middlewareFunction)`. El middleware también se puede encadenar dentro de la definición de la ruta.
 
-Look at the following example:
+Veamos el siguiente ejemplo:
 
 ```js
 app.get('/user', function(req, res, next) {
@@ -21,17 +21,17 @@ app.get('/user', function(req, res, next) {
 });
 ```
 
-This approach is useful to split the server operations into smaller units. That leads to a better app structure, and the possibility to reuse code in different places. This approach can also be used to perform some validation on the data. At each point of the middleware stack you can block the execution of the current chain and pass control to functions specifically designed to handle errors. Or you can pass control to the next matching route, to handle special cases. We will see how in the advanced Express section.
+Este método es útil para dividir las operaciones del servidor en unidades más pequeñas. Lo que lleva a una mejor estructura de nuestra aplicación y a la posibilidad de reutilizar código en diferentes lugares. Este método también se puede utilizar para realizar ciertas validaciones de los datos. En cada punto de la pila del middleware puedes bloquear la ejecución de la cadena actual y darle el control a funciones diseñadas específicamente para el manejo de errores. O puedes pasar el control a la siguiente ruta que concuerde, para manejar casos especiales. Veremos cómo en la sección avanzada de Express.
 
 # --instructions--
 
-In the route `app.get('/now', ...)` chain a middleware function and the final handler. In the middleware function you should add the current time to the request object in the `req.time` key. You can use `new Date().toString()`. In the handler, respond with a JSON object, taking the structure `{time: req.time}`.
+En la ruta `app.get('/now', ...)` encadena una función del middleware con el controlador final. En la función del middleware debes añadir la hora actual al objeto de petición en la clave `req.time`. Puedes utilizar `new Date().toString()`. En el controlador, responde con un objeto JSON, tomando la estructura `{time: req.time}`.
 
-**Note:** The test will not pass if you don’t chain the middleware. If you mount the function somewhere else, the test will fail, even if the output result is correct.
+**Nota:** La prueba no pasará si no encadenas el middleware. Si montas la función en otro lugar, la prueba fallará, incluso si el resultado de salida es correcto.
 
 # --hints--
 
-The /now endpoint should have mounted middleware
+El endpoint /now debe tener el middleware montado
 
 ```js
 (getUserInput) =>
@@ -49,7 +49,7 @@ The /now endpoint should have mounted middleware
   );
 ```
 
-The /now endpoint should return a time that is +/- 20 secs from now
+El endpoint /now debe devolver un tiempo que es +/- 20 segundos a partir de este momento
 
 ```js
 (getUserInput) =>
diff --git a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/get-data-from-post-requests.md b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/get-data-from-post-requests.md
index 8398c13973f..3c471eb82c0 100644
--- a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/get-data-from-post-requests.md
+++ b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/get-data-from-post-requests.md
@@ -1,6 +1,6 @@
 ---
 id: 587d7fb2367417b2b2512bf8
-title: Get Data from POST Requests
+title: Obtén datos de las peticiones POST
 challengeType: 2
 forumTopicId: 301511
 dashedName: get-data-from-post-requests
@@ -8,27 +8,27 @@ dashedName: get-data-from-post-requests
 
 # --description--
 
-Mount a POST handler at the path `/name`. It’s the same path as before. We have prepared a form in the html frontpage. It will submit the same data of exercise 10 (Query string). If the body-parser is configured correctly, you should find the parameters in the object `req.body`. Have a look at the usual library example:
+Monta un manejador POST en la ruta `/name`. Es la misma ruta de antes. Hemos preparado un formulario en la página principal html. Se enviarán los mismos datos del ejercicio 10 (Query string). Si el "body-parser" está configurado correctamente, debe encontrar los parámetros en el objeto `req.body`. Echa un vistazo al ejemplo de la biblioteca:
 
 <blockquote>route: POST '/library'<br>urlencoded_body: userId=546&#x26;bookId=6754 <br>req.body: {userId: '546', bookId: '6754'}</blockquote>
 
-Respond with the same JSON object as before: `{name: 'firstname lastname'}`. Test if your endpoint works using the html form we provided in the app frontpage.
+Responde con el mismo objeto JSON que antes: `{name: 'firstname lastname'}`. Prueba si tu endpoint funciona usando el formulario html que proporcionamos en la página principal de la aplicación.
 
-Tip: There are several other http methods other than GET and POST. And by convention there is a correspondence between the http verb, and the operation you are going to execute on the server. The conventional mapping is:
+Nota: Hay varios métodos de http diferentes a GET y POST. Y por convención hay una correspondencia entre el verbo http y la operación que se va a ejecutar en el servidor. La asignación convencional es:
 
-POST (sometimes PUT) - Create a new resource using the information sent with the request,
+POST (a veces PUT): Crea un nuevo recurso usando la información enviada con la solicitud,
 
-GET - Read an existing resource without modifying it,
+GET: Lee un recurso existente sin modificarlo,
 
-PUT or PATCH (sometimes POST) - Update a resource using the data sent,
+PUT o PATCH (a veces POST): Actualiza un recurso usando los datos enviados,
 
-DELETE => Delete a resource.
+DELETE => Elimina un recurso.
 
-There are also a couple of other methods which are used to negotiate a connection with the server. Except from GET, all the other methods listed above can have a payload (i.e. the data into the request body). The body-parser middleware works with these methods as well.
+También hay un par de otros métodos que se utilizan para negociar una conexión con el servidor. A excepción de GET, todos los demás métodos mencionados anteriormente pueden tener un payload (es decir, los datos en el cuerpo de la solicitud). El middleware body-parser también funciona con estos métodos.
 
 # --hints--
 
-Test 1 : Your API endpoint should respond with the correct name
+Prueba 1: El endpoint de tu API debe responder con el nombre correcto
 
 ```js
 (getUserInput) =>
@@ -46,7 +46,7 @@ Test 1 : Your API endpoint should respond with the correct name
   );
 ```
 
-Test 2 : Your API endpoint should respond with the correct name
+Prueba 2: El endpoint de tu API debe responder con el nombre correcto
 
 ```js
 (getUserInput) =>
diff --git a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/get-query-parameter-input-from-the-client.md b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/get-query-parameter-input-from-the-client.md
index 0d301a9f5e3..677e70b6ddf 100644
--- a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/get-query-parameter-input-from-the-client.md
+++ b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/get-query-parameter-input-from-the-client.md
@@ -1,6 +1,6 @@
 ---
 id: 587d7fb2367417b2b2512bf6
-title: Get Query Parameter Input from the Client
+title: Obtén la entrada de parámetros de consulta del cliente
 challengeType: 2
 forumTopicId: 301512
 dashedName: get-query-parameter-input-from-the-client
@@ -8,19 +8,19 @@ dashedName: get-query-parameter-input-from-the-client
 
 # --description--
 
-Another common way to get input from the client is by encoding the data after the route path, using a query string. The query string is delimited by a question mark (?), and includes field=value couples. Each couple is separated by an ampersand (&). Express can parse the data from the query string, and populate the object `req.query`. Some characters, like the percent (%), cannot be in URLs and have to be encoded in a different format before you can send them. If you use the API from JavaScript, you can use specific methods to encode/decode these characters.
+Otra forma común de obtener la entrada del cliente es codificando los datos después de la ruta, usando una cadena de consulta. La cadena de consulta está delimitada por un signo de interrogación (?), e incluye parejas de campo=valor. Cada pareja está separada por un ampersand (&). Express puede analizar los datos de la cadena de consulta, y llenar el objeto `req.query`. Algunos caracteres, como el porcentaje (%), no pueden estar en URLs y tienen que ser codificados en un formato diferente antes de poder enviarlos. Si usas la API desde JavaScript, puedes usar métodos específicos para codificar/decodificar estos caracteres.
 
 <blockquote>route_path: '/library'<br>actual_request_URL: '/library?userId=546&#x26;bookId=6754' <br>req.query: {userId: '546', bookId: '6754'}</blockquote>
 
 # --instructions--
 
-Build an API endpoint, mounted at `GET /name`. Respond with a JSON document, taking the structure `{ name: 'firstname lastname'}`. The first and last name parameters should be encoded in a query string e.g. `?first=firstname&last=lastname`.
+Construye un endpoint para el API, montado en `GET /name`. Responde con un documento JSON, tomando la estructura `{ name: 'firstname lastname'}`. Los parámetros del nombre y apellido deben codificarse en una cadena de consulta, por ejemplo, `?first=firstname&last=lastname`.
 
-**Note:** In the following exercise you are going to receive data from a POST request, at the same `/name` route path. If you want, you can use the method `app.route(path).get(handler).post(handler)`. This syntax allows you to chain different verb handlers on the same path route. You can save a bit of typing, and have cleaner code.
+**Nota:** En el siguiente ejercicio va a recibir datos de una solicitud POST, a la misma ruta `/name`. Si lo deseas, puedes utilizar el método `app.route(path).get(handler).post(handler)`. Esta sintaxis permite encadenar diferentes manejadores de verbos en la misma ruta. Puedes ahorrar un poco de escritura y tener un código más limpio.
 
 # --hints--
 
-Test 1 : Your API endpoint should respond with the correct name
+Prueba 1: El endpoint de tu API debe responder con el nombre correcto
 
 ```js
 (getUserInput) =>
@@ -38,7 +38,7 @@ Test 1 : Your API endpoint should respond with the correct name
   );
 ```
 
-Test 2 : Your API endpoint should respond with the correct name
+Prueba 2: El endpoint de tu API debe responder con el nombre correcto
 
 ```js
 (getUserInput) =>
diff --git a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/get-route-parameter-input-from-the-client.md b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/get-route-parameter-input-from-the-client.md
index b0055f569ea..86b2649ef32 100644
--- a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/get-route-parameter-input-from-the-client.md
+++ b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/get-route-parameter-input-from-the-client.md
@@ -1,6 +1,6 @@
 ---
 id: 587d7fb2367417b2b2512bf5
-title: Get Route Parameter Input from the Client
+title: Obtén la entrada de parámetros de ruta del cliente
 challengeType: 2
 forumTopicId: 301513
 dashedName: get-route-parameter-input-from-the-client
@@ -8,17 +8,17 @@ dashedName: get-route-parameter-input-from-the-client
 
 # --description--
 
-When building an API, we have to allow users to communicate to us what they want to get from our service. For example, if the client is requesting information about a user stored in the database, they need a way to let us know which user they're interested in. One possible way to achieve this result is by using route parameters. Route parameters are named segments of the URL, delimited by slashes (/). Each segment captures the value of the part of the URL which matches its position. The captured values can be found in the `req.params` object.
+Cuando construimos una API, tenemos que permitir que los usuarios nos comuniquen lo que quieren obtener de nuestro servicio. Por ejemplo, si el cliente solicita información sobre un usuario almacenado en la base de datos, necesitan una forma de hacernos saber en qué usuario están interesados. Una posible forma de lograr este resultado es utilizando parámetros de ruta. Los parámetros de ruta son segmentos con nombre de la URL, delimitados por barras (/). Cada segmento captura el valor de la parte de la URL que coincide con su posición. Los valores capturados pueden encontrarse en el objeto `req.params`.
 
 <blockquote>route_path: '/user/:userId/book/:bookId'<br>actual_request_URL: '/user/546/book/6754' <br>req.params: {userId: '546', bookId: '6754'}</blockquote>
 
 # --instructions--
 
-Build an echo server, mounted at the route `GET /:word/echo`. Respond with a JSON object, taking the structure `{echo: word}`. You can find the word to be repeated at `req.params.word`. You can test your route from your browser's address bar, visiting some matching routes, e.g. `your-app-rootpath/freecodecamp/echo`.
+Construye un servidor de eco, montado en la ruta `GET /:word/echo`. Responde con un documento JSON, tomando la estructura `{echo: word}`. Puedes encontrar la palabra que se repetirá en `req.params.word`. Puedes probar tu ruta desde la barra de direcciones de tu navegador, visitando algunas rutas coincidentes, por ejemplo, `your-app-rootpath/freecodecamp/echo`.
 
 # --hints--
 
-Test 1 : Your echo server should repeat words correctly
+Prueba 1: Tu servidor de eco debe repetir las palabras correctamente
 
 ```js
 (getUserInput) =>
@@ -36,7 +36,7 @@ Test 1 : Your echo server should repeat words correctly
   );
 ```
 
-Test 2 : Your echo server should repeat words correctly
+Prueba 2: Tu servidor de eco debe repetir las palabras correctamente
 
 ```js
 (getUserInput) =>
diff --git a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/implement-a-root-level-request-logger-middleware.md b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/implement-a-root-level-request-logger-middleware.md
index 2a2faa35c39..c101d96b214 100644
--- a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/implement-a-root-level-request-logger-middleware.md
+++ b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/implement-a-root-level-request-logger-middleware.md
@@ -1,6 +1,6 @@
 ---
 id: 587d7fb1367417b2b2512bf3
-title: Implement a Root-Level Request Logger Middleware
+title: Implementa un Middleware de registro de peticiones a nivel raíz
 challengeType: 2
 forumTopicId: 301514
 dashedName: implement-a-root-level-request-logger-middleware
@@ -8,9 +8,9 @@ dashedName: implement-a-root-level-request-logger-middleware
 
 # --description--
 
-Earlier, you were introduced to the `express.static()` middleware function. Now it’s time to see what middleware is, in more detail. Middleware functions are functions that take 3 arguments: the request object, the response object, and the next function in the application’s request-response cycle. These functions execute some code that can have side effects on the app, and usually add information to the request or response objects. They can also end the cycle by sending a response when some condition is met. If they don’t send the response when they are done, they start the execution of the next function in the stack. This triggers calling the 3rd argument, `next()`.
+Anteriormente, se te presentó la función de middleware `express.static()`. Ahora es el momento de ver lo que es un middleware con más detalle. Las funciones de Middleware son funciones que toman 3 argumentos: el objeto de la petición, el objeto de respuesta y la siguiente función en el ciclo petición-respuesta de la aplicación. Estas funciones ejecutan algún código que puede tener efectos secundarios en la aplicación, y normalmente agregan información a los objetos de la petición o respuesta. También pueden terminar el ciclo enviando una respuesta cuando se cumple alguna condición. Si no envían la respuesta cuando han terminado, comienzan la ejecución de la siguiente función en la pila de ejecución. Esto hace que se llame al tercer argumento, `next()`.
 
-Look at the following example:
+Veamos el siguiente ejemplo:
 
 ```js
 function(req, res, next) {
@@ -19,17 +19,17 @@ function(req, res, next) {
 }
 ```
 
-Let’s suppose you mounted this function on a route. When a request matches the route, it displays the string “I’m a middleware…”, then it executes the next function in the stack. In this exercise, you are going to build root-level middleware. As you have seen in challenge 4, to mount a middleware function at root level, you can use the `app.use(<mware-function>)` method. In this case, the function will be executed for all the requests, but you can also set more specific conditions. For example, if you want a function to be executed only for POST requests, you could use `app.post(<mware-function>)`. Analogous methods exist for all the HTTP verbs (GET, DELETE, PUT, …).
+Supongamos que montaste esta función en una ruta. Cuando una solicitud coincide con la ruta, muestra la cadena “I'm a middleware…”, luego ejecuta la siguiente función en la pila de ejecución. En este ejercicio, vas a construir un middleware a nivel raíz. Como has visto en el desafío 4, para montar una función middleware a nivel raíz, puedes usar el método `app.use(<mware-function>)`. En este caso, la función se ejecutará para todas las peticiones, pero también se pueden establecer condiciones más específicas. Por ejemplo, si quieres que una función se ejecute sólo para solicitudes POST, puedes usar `app.post(<mware-function>)`. Existen métodos análogos para todos los verbos HTTP (GET, DELETE, PUT, …).
 
 # --instructions--
 
-Build a simple logger. For every request, it should log to the console a string taking the following format: `method path - ip`. An example would look like this: `GET /json - ::ffff:127.0.0.1`. Note that there is a space between `method` and `path` and that the dash separating `path` and `ip` is surrounded by a space on both sides. You can get the request method (http verb), the relative route path, and the caller’s ip from the request object using `req.method`, `req.path` and `req.ip`. Remember to call `next()` when you are done, or your server will be stuck forever. Be sure to have the ‘Logs’ opened, and see what happens when some request arrives.
+Construye un simple registrador. Para cada petición, debe registrar en la consola una cadena con el siguiente formato: `method path - ip`. Un ejemplo se vería así: `GET /json - ::ffff:127.0.0.1`. Ten en cuenta que hay un espacio entre `method` y `path` y que el guión que separa `path` e `ip` está rodeado por un espacio en ambos lados. Puedes obtener el método de solicitud (http verb), la ruta de ruta relativa y la ip del cliente desde el objeto de la petición usando `req.method`, `req.path` y `req.ip`. Recuerda llamar a `next()` cuando hayas terminado, o tu servidor permanecerá bloqueado permanentemente. Asegúrate de tener abiertos los "registros" y comprueba lo que sucede cuando llega una solicitud.
 
-**Note:** Express evaluates functions in the order they appear in the code. This is true for middleware too. If you want it to work for all the routes, it should be mounted before them.
+**Nota:** Express evalúa las funciones en el orden en que aparecen en el código. Esto también es cierto para los middleware. Si quieres que funcione para todas las rutas, debe montarse antes que ellas.
 
 # --hints--
 
-Root level logger middleware should be active
+El middleware de registro a nivel raíz debe estar activo
 
 ```js
 (getUserInput) =>
diff --git a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/serve-an-html-file.md b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/serve-an-html-file.md
index 1d618673227..4d33c4b6dfe 100644
--- a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/serve-an-html-file.md
+++ b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/serve-an-html-file.md
@@ -1,6 +1,6 @@
 ---
 id: 587d7fb0367417b2b2512bef
-title: Serve an HTML File
+title: Sirve un archivo HTML
 challengeType: 2
 forumTopicId: 301516
 dashedName: serve-an-html-file
@@ -8,7 +8,7 @@ dashedName: serve-an-html-file
 
 # --description--
 
-You can respond to requests with a file using the `res.sendFile(path)` method. You can put it inside the `app.get('/', ...)` route handler. Behind the scenes, this method will set the appropriate headers to instruct your browser on how to handle the file you want to send, according to its type. Then it will read and send the file. This method needs an absolute file path. We recommend you to use the Node global variable `__dirname` to calculate the path like this:
+Puedes responder a peticiones con un archivo utilizando el método `res.sendFile(path)`. Puedes ponerlo dentro del gestor de rutas `app.get('/', ...)`. En segundo plano, este método establecerá las cabeceras apropiadas para indicar a tu navegador cómo manejar el archivo que se desea enviar, de acuerdo a su tipo. Entonces leerá y enviará el archivo. Este método necesita una ruta de archivo absoluta. Te recomendamos que uses la variable global de Node `__dirname` para calcular la ruta como esta:
 
 ```js
 absolutePath = __dirname + relativePath/file.ext
@@ -16,13 +16,13 @@ absolutePath = __dirname + relativePath/file.ext
 
 # --instructions--
 
-Send the `/views/index.html` file as a response to GET requests to the `/` path. If you view your live app, you should see a big HTML heading (and a form that we will use later…), with no style applied.
+Envía el archivo `/views/index.html` como respuesta a las solicitudes GET a la ruta `/`. Si ves tu aplicación en vivo, debes ver un gran encabezado HTML (y un formulario que usaremos más adelante…), sin ningún estilo aplicado.
 
-**Note:** You can edit the solution of the previous challenge or create a new one. If you create a new solution, keep in mind that Express evaluates routes from top to bottom, and executes the handler for the first match. You have to comment out the preceding solution, or the server will keep responding with a string.
+**Nota:** Puedes editar la solución del desafío anterior o crear uno nuevo. Si creas una nueva solución, ten en cuenta que Express evalúa las rutas de arriba a abajo, y ejecuta el manejador para la primera coincidencia. Tienes que comentar la solución anterior, o el servidor seguirá respondiendo con una cadena.
 
 # --hints--
 
-Your app should serve the file views/index.html
+Tu app debe servir el archivo views/index.html
 
 ```js
 (getUserInput) =>
diff --git a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/serve-json-on-a-specific-route.md b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/serve-json-on-a-specific-route.md
index 1e977061c7c..d8b1bbe8c83 100644
--- a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/serve-json-on-a-specific-route.md
+++ b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/serve-json-on-a-specific-route.md
@@ -1,6 +1,6 @@
 ---
 id: 587d7fb1367417b2b2512bf1
-title: Serve JSON on a Specific Route
+title: Sirve JSON en una ruta específica
 challengeType: 2
 forumTopicId: 301517
 dashedName: serve-json-on-a-specific-route
@@ -8,17 +8,17 @@ dashedName: serve-json-on-a-specific-route
 
 # --description--
 
-While an HTML server serves HTML, an API serves data. A <dfn>REST</dfn> (REpresentational State Transfer) API allows data exchange in a simple way, without the need for clients to know any detail about the server. The client only needs to know where the resource is (the URL), and the action it wants to perform on it (the verb). The GET verb is used when you are fetching some information, without modifying anything. These days, the preferred data format for moving information around the web is JSON. Simply put, JSON is a convenient way to represent a JavaScript object as a string, so it can be easily transmitted.
+Mientras que un servidor HTML sirve HTML, una API sirve datos. Una API <dfn>REST</dfn> (REpresentational State Transfer) permite el intercambio de datos de una manera sencilla, sin necesidad de que los clientes conozcan ningún detalle sobre el servidor. El cliente sólo necesita saber dónde está el recurso (la URL), y la acción que quiere realizar en él (el verbo). El verbo GET se utiliza cuando se obtiene alguna información, sin modificar nada. En la actualidad, el formato de datos preferido para mover información por la web es JSON. En pocas palabras, JSON es una manera conveniente de representar un objeto JavaScript como una cadena de texto, por lo que puede ser fácilmente transmitido.
 
-Let's create a simple API by creating a route that responds with JSON at the path `/json`. You can do it as usual, with the `app.get()` method. Inside the route handler, use the method `res.json()`, passing in an object as an argument. This method closes the request-response loop, returning the data. Behind the scenes, it converts a valid JavaScript object into a string, then sets the appropriate headers to tell your browser that you are serving JSON, and sends the data back. A valid object has the usual structure `{key: data}`. `data` can be a number, a string, a nested object or an array. `data` can also be a variable or the result of a function call, in which case it will be evaluated before being converted into a string.
+Vamos a crear una API simple creando una ruta que responda con JSON en la ruta `/json`. Puedes hacerlo como de costumbre, con el método `app.get()`. Dentro del manejador de ruta, utiliza el método `res.json()`, pasando un objeto como argumento. Este método cierra el bucle de solicitud y respuesta, devolviendo los datos. Tras bambalinas, convierte un objeto JavaScript en una cadena, luego establece las cabeceras apropiadas para decirle a tu navegador que está sirviendo JSON, y devuelve los datos. Un objeto válido tiene la estructura habitual `{key: data}`. `data` puede ser un número, una cadena de texto, un objeto anidado o un arreglo. `data` también puede ser una variable o el resultado de una llamada a una función, en cuyo caso será evaluado antes de ser convertido en una cadena de texto.
 
 # --instructions--
 
-Serve the object `{"message": "Hello json"}` as a response, in JSON format, to GET requests to the `/json` route. Then point your browser to `your-app-url/json`, you should see the message on the screen.
+Sirve el objeto `{"message": "Hello json"}` como respuesta, en formato JSON, a las solicitudes GET en la ruta `/json`. A continuación, apunta tu navegador a `your-app-url/json`, debes ver el mensaje en la pantalla.
 
 # --hints--
 
-The endpoint `/json` should serve the json object `{"message": "Hello json"}`
+El endpoint `/json` debe servir el objeto json `{"message": "Hello json"}`
 
 ```js
 (getUserInput) =>
diff --git a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/serve-static-assets.md b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/serve-static-assets.md
index f3e2796c54e..bad41c52b1a 100644
--- a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/serve-static-assets.md
+++ b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/serve-static-assets.md
@@ -1,6 +1,6 @@
 ---
 id: 587d7fb0367417b2b2512bf0
-title: Serve Static Assets
+title: Sirve recursos estáticos
 challengeType: 2
 forumTopicId: 301518
 dashedName: serve-static-assets
@@ -8,21 +8,21 @@ dashedName: serve-static-assets
 
 # --description--
 
-An HTML server usually has one or more directories that are accessible by the user. You can place there the static assets needed by your application (stylesheets, scripts, images).
+Un servidor HTML normalmente tiene uno o más directorios a los que el usuario puede acceder. Puedes colocar allí los recursos estáticos que necesite tu aplicación (hojas de estilo, scripts, imágenes).
 
-In Express, you can put in place this functionality using the middleware `express.static(path)`, where the `path` parameter is the absolute path of the folder containing the assets.
+En Express, puedes poner en marcha esta funcionalidad utilizando el middleware `express.static(path)`, donde el parámetro `path` es la ruta absoluta de la carpeta que contiene los recursos.
 
-If you don’t know what middleware is... don’t worry, we will discuss in detail later. Basically, middleware are functions that intercept route handlers, adding some kind of information. A middleware needs to be mounted using the method `app.use(path, middlewareFunction)`. The first `path` argument is optional. If you don’t pass it, the middleware will be executed for all requests.
+Si no sabes qué es middleware... no te preocupes, hablaremos en detalle más adelante. Básicamente, middleware son funciones que interceptan los manejadores de rutas, añadiendo algún tipo de información. Un middleware necesita ser montado usando el método `app.use(path, middlewareFunction)`. El primer argumento de `path` es opcional. Si no lo pasas, el middleware se ejecutará para todas las peticiones.
 
 # --instructions--
 
-Mount the `express.static()` middleware to the path `/public` with `app.use()`. The absolute path to the assets folder is `__dirname + /public`.
+Monta el middleware `express.static()` a la ruta `/public` con `app.use()`. La ruta absoluta a la carpeta de recursos es `__dirname + /public`.
 
-Now your app should be able to serve a CSS stylesheet. Note that the `/public/style.css` file is referenced in the `/views/index.html` in the project boilerplate. Your front-page should look a little better now!
+Ahora tu aplicación debe ser capaz de servir una hoja de estilos CSS. Ten en cuenta que el archivo `/public/style.css` está referenciado en el archivo `/views/index.html` en el plantilla del proyecto. ¡Tu página principal debería verse un poco mejor ahora!
 
 # --hints--
 
-Your app should serve asset files from the `/public` directory to the `/public` path
+Tu aplicación debe servir archivos de recursos desde el directorio `/public` a la ruta `/public`
 
 ```js
 (getUserInput) =>
diff --git a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/start-a-working-express-server.md b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/start-a-working-express-server.md
index e8e3e82fc5a..5052d93e20c 100644
--- a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/start-a-working-express-server.md
+++ b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/start-a-working-express-server.md
@@ -1,6 +1,6 @@
 ---
 id: 587d7fb0367417b2b2512bee
-title: Start a Working Express Server
+title: Inicia un servidor Express
 challengeType: 2
 forumTopicId: 301519
 dashedName: start-a-working-express-server
@@ -8,9 +8,9 @@ dashedName: start-a-working-express-server
 
 # --description--
 
-In the first two lines of the file `myApp.js`, you can see how easy it is to create an Express app object. This object has several methods, and you will learn many of them in these challenges. One fundamental method is `app.listen(port)`. It tells your server to listen on a given port, putting it in running state. For testing reasons, we need the app to be running in the background so we added this method in the `server.js` file for you.
+En las primeras dos líneas del archivo `myApp.js`, puedes ver lo fácil que es crear un objeto app Express. Este objeto tiene varios métodos, y aprenderás muchos de ellos en estos desafíos. Un método fundamental es `app.listen(port)`. Le dice a tu servidor que escuche en un puerto determinado, poniéndolo en estado de ejecución. Por razones de prueba, necesitamos que la aplicación se ejecute en segundo plano, así que añadimos este método en el archivo `server.js` para ti.
 
-Let’s serve our first string! In Express, routes takes the following structure: `app.METHOD(PATH, HANDLER)`. METHOD is an http method in lowercase. PATH is a relative path on the server (it can be a string, or even a regular expression). HANDLER is a function that Express calls when the route is matched. Handlers take the form `function(req, res) {...}`, where req is the request object, and res is the response object. For example, the handler
+¡Sirvamos nuestra primer cadena! En Express, las rutas toman la siguiente estructura: `app.METHOD(PATH, HANDLER)`. METHOD es un método http en minúsculas. PATH es una ruta relativa en el servidor (puede ser una cadena, o incluso una expresión regular). HANDLER es una función que Express llama cuando la ruta coincide. Los Handlers toman la forma `function(req, res) {...}`, donde req es el objeto de la solicitud, y res es el objeto de respuesta. Por ejemplo, el handler
 
 ```js
 function(req, res) {
@@ -18,17 +18,17 @@ function(req, res) {
 }
 ```
 
-will serve the string 'Response String'.
+servirá la cadena 'Response String'.
 
 # --instructions--
 
-Use the `app.get()` method to serve the string "Hello Express" to GET requests matching the `/` (root) path. Be sure that your code works by looking at the logs, then see the results in the preview if you are using Replit.
+Utiliza el método `app.get()` para servir la cadena "Hello Express" a las peticiones GET que coincidan con la ruta `/` (raíz). Asegúrate de que tu código funciona mirando los registros, luego ve los resultados en la vista previa si estás usando Replit.
 
-**Note:** All the code for these lessons should be added in between the few lines of code we have started you off with.
+**Nota:** Todo el código de estas lecciones debe añadirse entre las pocas líneas de código con las que hemos iniciado.
 
 # --hints--
 
-Your app should serve the string 'Hello Express'
+Tu aplicación debe mostrarte en consola la cadena 'Hello Express'
 
 ```js
 (getUserInput) =>
diff --git a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/use-body-parser-to-parse-post-requests.md b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/use-body-parser-to-parse-post-requests.md
index 5baf9fc636e..9008541c06c 100644
--- a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/use-body-parser-to-parse-post-requests.md
+++ b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/use-body-parser-to-parse-post-requests.md
@@ -1,6 +1,6 @@
 ---
 id: 587d7fb2367417b2b2512bf7
-title: Use body-parser to Parse POST Requests
+title: Usa body-parser para analizar las peticiones POST
 challengeType: 2
 forumTopicId: 301520
 dashedName: use-body-parser-to-parse-post-requests
@@ -8,9 +8,9 @@ dashedName: use-body-parser-to-parse-post-requests
 
 # --description--
 
-Besides GET, there is another common HTTP verb, it is POST. POST is the default method used to send client data with HTML forms. In REST convention, POST is used to send data to create new items in the database (a new user, or a new blog post). You don’t have a database in this project, but you are going to learn how to handle POST requests anyway.
+Además de GET, hay otro verbo HTTP común, es POST. POST es el método por defecto utilizado para enviar datos del cliente con formularios HTML. En la convención REST, POST se utiliza para enviar datos para crear nuevos elementos en la base de datos (un nuevo usuario, o una nueva entrada de blog). No tienes una base de datos en este proyecto, pero de todos modos aprenderás a manejar las peticiones POST.
 
-In these kind of requests, the data doesn’t appear in the URL, it is hidden in the request body. The body is a part of the HTTP request, also called the payload. Even though the data is not visible in the URL, this does not mean that it is private. To see why, look at the raw content of an HTTP POST request:
+En este tipo de peticiones, los datos no aparecen en la URL, están ocultos en el cuerpo de la petición. El cuerpo es parte de la petición HTTP, también llamada la carga útil. Aunque los datos no son visibles en la URL, esto no significa que sean privados. Para ver por qué, mire el contenido bruto de una petición HTTP POST:
 
 ```http
 POST /path/subpath HTTP/1.0
@@ -22,19 +22,19 @@ Content-Length: 20
 name=John+Doe&age=25
 ```
 
-As you can see, the body is encoded like the query string. This is the default format used by HTML forms. With Ajax, you can also use JSON to handle data having a more complex structure. There is also another type of encoding: multipart/form-data. This one is used to upload binary files. In this exercise, you will use a urlencoded body. To parse the data coming from POST requests, you have to install the `body-parser` package. This package allows you to use a series of middleware, which can decode data in different formats.
+Como puedes ver, el cuerpo está codificado como la cadena de consulta. Este es el formato por defecto utilizado por los formularios HTML. Con Ajax, también puedes utilizar JSON para manejar datos con una estructura más compleja. También hay otro tipo de codificación: multiparte/form-data. Este se utiliza para subir archivos binarios. En este ejercicio, usarás un cuerpo urlencoded. Para analizar los datos provenientes de peticiones POST, tienes que instalar el paquete `body-parser`. Este paquete te permite usar una serie de middleware, que pueden decodificar datos en diferentes formatos.
 
 # --instructions--
 
-Install the `body-parser` module in your `package.json`. Then, `require` it at the top of the file. Store it in a variable named `bodyParser`. The middleware to handle urlencoded data is returned by `bodyParser.urlencoded({extended: false})`. Pass the function returned by the previous method call to `app.use()`. As usual, the middleware must be mounted before all the routes that depend on it.
+Instala el módulo `body-parser` en tu `package.json`. Luego, agrega `require` en la parte superior del archivo con el nuevo módulo. Almacénelo en una variable llamada `bodyParser`. El middleware para manejar datos urlencoded es devuelto por `bodyParser.urlencoded({extended: false})`. Pasa la función devuelta por el método anterior llamada a `app.use()`. Como de costumbre, el middleware debe ser montado antes de todas las rutas que dependen de él.
 
-**Note:** `extended` is a configuration option that tells `body-parser` which parsing needs to be used. When `extended=false` it uses the classic encoding `querystring` library. When `extended=true` it uses `qs` library for parsing.
+**Nota:** `extended` es una opción de configuración que le dice a `body-parser` qué análisis necesita ser usado. Cuando `extended=false`, utiliza la biblioteca `querystring` de codificación clásica. Cuando `extended=true` utiliza la biblioteca `qs` para analizar la sintaxis.
 
-When using `extended=false`, values can be only strings or arrays. The object returned when using `querystring` does not prototypically inherit from the default JavaScript `Object`, which means functions like `hasOwnProperty`, `toString` will not be available. The extended version allows more data flexibility, but it is outmatched by JSON.
+Cuando se utiliza `extended=false`, los valores sólo pueden ser cadenas o arreglos. El objeto devuelto al usar `querystring` no hereda de forma prototípica del `Object` de JavaScript por defecto, lo que significa que funciones como `hasOwnProperty`, `toString` no estarán disponibles. La versión "extended" permite más flexibilidad de datos, pero es superada por JSON.
 
 # --hints--
 
-The 'body-parser' middleware should be mounted
+El middleware 'body-parser' debe ser montado
 
 ```js
 (getUserInput) =>
diff --git a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/use-the-.env-file.md b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/use-the-.env-file.md
index e953553f4be..12f586e435e 100644
--- a/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/use-the-.env-file.md
+++ b/curriculum/challenges/espanol/05-back-end-development-and-apis/basic-node-and-express/use-the-.env-file.md
@@ -1,6 +1,6 @@
 ---
 id: 587d7fb1367417b2b2512bf2
-title: Use the .env File
+title: Usa el archivo .env
 challengeType: 2
 forumTopicId: 301521
 dashedName: use-the--env-file
@@ -8,23 +8,25 @@ dashedName: use-the--env-file
 
 # --description--
 
-The `.env` file is a hidden file that is used to pass environment variables to your application. This file is secret, no one but you can access it, and it can be used to store data that you want to keep private or hidden. For example, you can store API keys from external services or your database URI. You can also use it to store configuration options. By setting configuration options, you can change the behavior of your application, without the need to rewrite some code.
+El archivo `.env` es un archivo oculto que se utiliza para pasar variables de entorno a la aplicación. Este archivo es secreto, solamente tú puedes acceder a él, y puede ser utilizado para almacenar datos que desees mantener privados u ocultos. Por ejemplo, puedes almacenar claves de APIs de servicios externos o la URI de tu base de datos. También puedes usarlo para guardar opciones de configuración. Modificando las opciones de configuración, puedes cambiar el comportamiento de tu aplicación, sin necesidad de reescribir código.
 
-The environment variables are accessible from the app as `process.env.VAR_NAME`. The `process.env` object is a global Node object, and variables are passed as strings. By convention, the variable names are all uppercase, with words separated by an underscore. The `.env` is a shell file, so you don’t need to wrap names or values in quotes. It is also important to note that there cannot be space around the equals sign when you are assigning values to your variables, e.g. `VAR_NAME=value`. Usually, you will put each variable definition on a separate line.
+Las variables de entorno son accesibles desde la aplicación como `process.env.VAR_NAME`. El objeto `process.env` es un objeto global de Node, y las variables son pasadas como cadenas de texto. Por convención, los nombres de las variables son en letras mayúsculas, con las palabras separadas por guión bajo. El archivo `.env` es un archivo shell, por lo que no es necesario incluir los nombres o valores entre comillas. También es importante tener en cuenta que no pueden haber espacios alrededor del signo de igual cuando se asignan valores a las variables, por ejemplo: `VAR_NAME=value`. Normalmente, usted pondrá cada definición de variable en una línea separada.
 
 # --instructions--
 
-Let's add an environment variable as a configuration option.
+Añadamos una variable de entorno como opción de configuración.
 
-Create a `.env` file in the root of your project directory, and store the variable `MESSAGE_STYLE=uppercase` in it.
+Crea un archivo `.env` en la raíz del directorio de tu proyecto y almacena la variable `MESSAGE_STYLE=uppercase` en él.
 
-Then, in the `/json` GET route handler you created in the last challenge, transform the response object's message to uppercase if `process.env.MESSAGE_STYLE` equals `uppercase`. The response object should either be `{"message": "Hello json"}` or `{"message": "HELLO JSON"}`, depending on the `MESSAGE_STYLE` value.
+Luego, en el manejador de rutas `/json` GET creado en el último desafío, transforma el mensaje del objeto de respuesta a mayúsculas si `process.env.MESSAGE_STYLE` es igual a `uppercase`. El objeto de respuesta debe ser `{"message": "Hello json"}` o `{"message": "HELLO JSON"}`, dependiendo del valor `MESSAGE_STYLE`.
 
-**Note:** If you are using Replit, you cannot create a `.env` file. Instead, use the built-in <dfn>SECRETS</dfn> tab to add the variable.
+**Nota:** Si estás usando Replit, no puedes crear un archivo `.env`. En su lugar, utiliza la pestaña integrada <dfn>SECRETS</dfn> para añadir la variable.
+
+Si estás trabajando localmente, necesitarás el paquete `dotenv`. Carga variables de entorno desde tu archivo `.env` en `process.env`. Instálalo con `npm install dotenv`. Luego, en la parte superior de tu archivo `myApp.js`, importa y carga las variables con `require('dotenv').config()`.
 
 # --hints--
 
-The response of the endpoint `/json` should change according to the environment variable `MESSAGE_STYLE`
+La respuesta del endpoint `/json` debe cambiar de acuerdo a la variable de entorno `MESSAGE_STYLE`
 
 ```js
 (getUserInput) =>
diff --git a/curriculum/challenges/italian/01-responsive-web-design/applied-accessibility/use-headings-to-show-hierarchical-relationships-of-content.md b/curriculum/challenges/italian/01-responsive-web-design/applied-accessibility/use-headings-to-show-hierarchical-relationships-of-content.md
index d997fd32508..abcd3bafcfa 100644
--- a/curriculum/challenges/italian/01-responsive-web-design/applied-accessibility/use-headings-to-show-hierarchical-relationships-of-content.md
+++ b/curriculum/challenges/italian/01-responsive-web-design/applied-accessibility/use-headings-to-show-hierarchical-relationships-of-content.md
@@ -17,7 +17,7 @@ Se stai scrivendo un articolo con un'introduzione, un corpo, e una conclusione,
 
 Le intestazioni di rango uguale (o superiore) iniziano nuove sezioni implicite, intestazioni di rango minore iniziano sottosezioni di quella precedente.
 
-Ad esempio, una pagina con un elemento `h2` seguito da diverse sottosezioni etichettate con tag `h4` confonderebbe un utente di screen reader. Con sei scelte, è allettante utilizzare un tag perché appare meglio nel browser, ma ricorda che puoi utilizzare CSS per modificarne la dimensione.
+Ad esempio, una pagina con un elemento `h2` seguito da diverse sottosezioni etichettate con elementi `h4` confonderebbe un utente di screen reader. Con sei scelte, è allettante utilizzare un tag perché appare meglio nel browser, ma ricorda che puoi utilizzare CSS per modificarne la dimensione.
 
 Un ultimo punto: ogni pagina dovrebbe avere sempre uno (e uno solo) elemento `h1`, relativo al tema principale del tuo contenuto. Questa e le altre intestazioni sono utilizzate in parte dai motori di ricerca per capire l'argomento della pagina.
 
@@ -27,7 +27,7 @@ Camper Cat vuole una pagina sul suo sito dedicata a come diventare un ninja. Aiu
 
 # --hints--
 
-Il tuo codice dovrebbe avere 6 tag `h3`.
+Il tuo codice dovrebbe avere 6 elementi `h3`.
 
 ```js
 assert($('h3').length === 6);
@@ -39,7 +39,7 @@ Il tuo codice dovrebbe avere 6 tag di chiusura `h3`.
 assert((code.match(/\/h3/g) || []).length === 6);
 ```
 
-Il tuo codice non dovrebbe avere alcun tag `h5`.
+Il tuo codice non dovrebbe avere alcun elemento `h5`.
 
 ```js
 assert($('h5').length === 0);
diff --git a/curriculum/challenges/italian/01-responsive-web-design/applied-visual-design/adjust-the-size-of-a-heading-element-versus-a-paragraph-element.md b/curriculum/challenges/italian/01-responsive-web-design/applied-visual-design/adjust-the-size-of-a-heading-element-versus-a-paragraph-element.md
index 56204bf5d45..2c478a2e415 100644
--- a/curriculum/challenges/italian/01-responsive-web-design/applied-visual-design/adjust-the-size-of-a-heading-element-versus-a-paragraph-element.md
+++ b/curriculum/challenges/italian/01-responsive-web-design/applied-visual-design/adjust-the-size-of-a-heading-element-versus-a-paragraph-element.md
@@ -1,6 +1,6 @@
 ---
 id: 587d781b367417b2b2512abd
-title: Regolare la dimensione di un'intestazione rispetto a quella di un paragrafo
+title: Regolare la dimensione di un elemento di intestazione rispetto a quella di un elemento paragrafo
 challengeType: 0
 videoUrl: 'https://scrimba.com/c/c3bRPTz'
 forumTopicId: 301037
@@ -9,11 +9,11 @@ dashedName: adjust-the-size-of-a-heading-element-versus-a-paragraph-element
 
 # --description--
 
-La dimensione del carattere dei tag di intestazione (da `h1` a `h6`) dovrebbe essere generalmente più grande della dimensione del carattere dei tag di paragrafo. Questo rende più facile per l'utente capire visivamente il layout e il livello di importanza di ogni elemento della pagina. Si utilizza la proprietà `font-size` per regolare la dimensione del testo in un elemento.
+La dimensione del carattere degli elementi di intestazione (da `h1` a `h6`) dovrebbe essere generalmente più grande della dimensione del carattere degli elementi di paragrafo. Questo rende più facile per l'utente capire visivamente il layout e il livello di importanza di ogni elemento della pagina. Si utilizza la proprietà `font-size` per regolare la dimensione del testo in un elemento.
 
 # --instructions--
 
-Per rendere l'intestazione significativamente più grande del paragrafo, porta `font-size` del tag `h4` a 27 pixel.
+Per rendere l'intestazione significativamente più grande del paragrafo, porta `font-size` dell'elemento `h4` a 27 pixel.
 
 # --hints--
 
@@ -116,3 +116,4 @@ assert($('h4').css('font-size') == '27px');
   </div>
 </div>
 ```
+
diff --git a/curriculum/challenges/italian/01-responsive-web-design/applied-visual-design/create-visual-balance-using-the-text-align-property.md b/curriculum/challenges/italian/01-responsive-web-design/applied-visual-design/create-visual-balance-using-the-text-align-property.md
index 702bfb2cbb2..bafd04a6709 100644
--- a/curriculum/challenges/italian/01-responsive-web-design/applied-visual-design/create-visual-balance-using-the-text-align-property.md
+++ b/curriculum/challenges/italian/01-responsive-web-design/applied-visual-design/create-visual-balance-using-the-text-align-property.md
@@ -13,7 +13,7 @@ Questa sezione del curriculum si concentra sul Visual Design applicato. Il primo
 
 Il testo è spesso una buona parte del contenuto web. Il CSS ha diverse opzioni su come allinearlo con la proprietà `text-align`.
 
-`text-align: justify;` fa sì che tutte le righe di testo tranne l'ultima riga incontrino i bordi sinistro e destro della riga.
+`text-align: justify;` spazia il testo in modo che ogni riga abbia la stessa lunghezza.
 
 `text-align: center;` centra il testo
 
diff --git a/curriculum/challenges/italian/01-responsive-web-design/applied-visual-design/use-the-s-tag-to-strikethrough-text.md b/curriculum/challenges/italian/01-responsive-web-design/applied-visual-design/use-the-s-tag-to-strikethrough-text.md
index 82af33cf422..b891883d61c 100644
--- a/curriculum/challenges/italian/01-responsive-web-design/applied-visual-design/use-the-s-tag-to-strikethrough-text.md
+++ b/curriculum/challenges/italian/01-responsive-web-design/applied-visual-design/use-the-s-tag-to-strikethrough-text.md
@@ -13,7 +13,7 @@ Per barrare il testo, ovvero tracciare una linea orizzontale che tagli i caratte
 
 # --instructions--
 
-Avvolgi il tag `s` intorno a `Google` all'interno del tag `h4`, quindi aggiungi la parola `Alphabet` accanto ad esso, senza applicarle la formattazione barrata.
+Avvolgi le tag `s` attorno a `Google` dentro le tag `h4` e poi aggiungi la parola `Alphabet` affianco senza la formattazione barrata.
 
 # --hints--
 
diff --git a/curriculum/challenges/italian/01-responsive-web-design/applied-visual-design/use-the-strong-tag-to-make-text-bold.md b/curriculum/challenges/italian/01-responsive-web-design/applied-visual-design/use-the-strong-tag-to-make-text-bold.md
index 8452d6cd859..351d9c13e8c 100644
--- a/curriculum/challenges/italian/01-responsive-web-design/applied-visual-design/use-the-strong-tag-to-make-text-bold.md
+++ b/curriculum/challenges/italian/01-responsive-web-design/applied-visual-design/use-the-strong-tag-to-make-text-bold.md
@@ -13,7 +13,7 @@ Per rendere il testo in grassetto, puoi usare il tag `strong`. Esso viene spesso
 
 # --instructions--
 
-Avvolgi un tag `strong` intorno al testo `Stanford University` all'interno del tag `p` (non includere il punto).
+Avvolgi le `strong` tag attorno al testo `Stanford University` dentro al tag `p` (non includere il punto!).
 
 # --hints--
 
diff --git a/curriculum/challenges/italian/01-responsive-web-design/basic-html-and-html5/check-radio-buttons-and-checkboxes-by-default.md b/curriculum/challenges/italian/01-responsive-web-design/basic-html-and-html5/check-radio-buttons-and-checkboxes-by-default.md
index 3d98d33115a..b9912572989 100644
--- a/curriculum/challenges/italian/01-responsive-web-design/basic-html-and-html5/check-radio-buttons-and-checkboxes-by-default.md
+++ b/curriculum/challenges/italian/01-responsive-web-design/basic-html-and-html5/check-radio-buttons-and-checkboxes-by-default.md
@@ -35,6 +35,18 @@ La prima casella di spunta del tuo modulo dovrebbe essere spuntata di default.
 assert($('input[type="checkbox"]').prop('checked'));
 ```
 
+Non dovresti cambiare il testo all'interno dell'etichetta `Indoor`.
+
+```js
+assert.equal(document.querySelector('label[for="indoor"]')?.innerText?.trim(), 'Indoor');
+```
+
+Non dovresti cambiare il testo all'interno dell'etichetta `Loving`.
+
+```js
+assert.equal(document.querySelector('label[for="loving"]')?.innerText?.trim(), 'Loving');
+```
+
 # --seed--
 
 ## --seed-contents--
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md
index 4ed5680ec7e..f6162996234 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md
@@ -18,9 +18,9 @@ Gli indici degli array sono scritti nella stessa notazione tra parentesi usata d
 **Esempio**
 
 ```js
-var array = [50,60,70];
+const array = [50, 60, 70];
 array[0];
-var data = array[1];
+const data = array[1];
 ```
 
 `array[0]` ora è `50` e `data` ha il valore `60`.
@@ -76,7 +76,7 @@ if(typeof myArray !== "undefined" && typeof myData !== "undefined"){(function(y,
 ## --seed-contents--
 
 ```js
-var myArray = [50,60,70];
+const myArray = [50, 60, 70];
 
 
 ```
@@ -84,6 +84,6 @@ var myArray = [50,60,70];
 # --solutions--
 
 ```js
-var myArray = [50,60,70];
-var myData = myArray[0];
+const myArray = [50, 60, 70];
+const myData = myArray[0];
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md
index 6dc9eca87b9..002237ffc8b 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md
@@ -14,12 +14,13 @@ dashedName: access-multi-dimensional-arrays-with-indexes
 **Esempio**
 
 ```js
-var arr = [
-  [1,2,3],
-  [4,5,6],
-  [7,8,9],
-  [[10,11,12], 13, 14]
+const arr = [
+  [1, 2, 3],
+  [4, 5, 6],
+  [7, 8, 9],
+  [[10, 11, 12], 13, 14]
 ];
+
 arr[3];
 arr[3][0];
 arr[3][0][1];
@@ -58,14 +59,19 @@ if(typeof myArray !== "undefined"){(function(){return "myData: " + myData + " my
 ## --seed-contents--
 
 ```js
-var myArray = [[1,2,3], [4,5,6], [7,8,9], [[10,11,12], 13, 14]];
+const myArray = [
+  [1, 2, 3],
+  [4, 5, 6],
+  [7, 8, 9],
+  [[10, 11, 12], 13, 14],
+];
 
-var myData = myArray[0][0];
+const myData = myArray[0][0];
 ```
 
 # --solutions--
 
 ```js
-var myArray = [[1,2,3],[4,5,6], [7,8,9], [[10,11,12], 13, 14]];
-var myData = myArray[2][1];
+const myArray = [[1, 2, 3], [4, 5, 6], [7, 8, 9], [[10, 11, 12], 13, 14]];
+const myData = myArray[2][1];
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md
index e4e3c271114..2521cb7174d 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md
@@ -14,7 +14,7 @@ Come abbiamo visto in precedenti esempi, gli oggetti possono contenere sia ogget
 Ecco un esempio di come accedere a un array nidificato:
 
 ```js
-var ourPets = [
+const ourPets = [
   {
     animalType: "cat",
     names: [
@@ -32,6 +32,7 @@ var ourPets = [
     ]
   }
 ];
+
 ourPets[0].names[1];
 ourPets[1].names[0];
 ```
@@ -72,7 +73,7 @@ assert(/=\s*myPlants\[1\].list\[1\]/.test(code));
 ## --seed-contents--
 
 ```js
-var myPlants = [
+const myPlants = [
   {
     type: "flowers",
     list: [
@@ -91,13 +92,13 @@ var myPlants = [
   }
 ];
 
-var secondTree = "";
+const secondTree = "";
 ```
 
 # --solutions--
 
 ```js
-var myPlants = [
+const myPlants = [
   {
     type: "flowers",
     list: [
@@ -116,5 +117,5 @@ var myPlants = [
   }
 ];
 
-var secondTree = myPlants[1].list[1];
+const secondTree = myPlants[1].list[1];
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md
index 0343cea510e..2a577d8e0a1 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md
@@ -14,7 +14,7 @@ Le sotto-proprietà degli oggetti possono essere accessibili concatenando insiem
 Ecco un oggetto nidificato:
 
 ```js
-var ourStorage = {
+const ourStorage = {
   "desk": {
     "drawer": "stapler"
   },
@@ -26,6 +26,7 @@ var ourStorage = {
     "bottom drawer": "soda"
   }
 };
+
 ourStorage.cabinet["top drawer"].folder2;
 ourStorage.desk.drawer;
 ```
@@ -66,7 +67,7 @@ assert(/=\s*myStorage\.car\.inside\[\s*("|')glove box\1\s*\]/g.test(code));
 ## --seed-contents--
 
 ```js
-var myStorage = {
+const myStorage = {
   "car": {
     "inside": {
       "glove box": "maps",
@@ -78,13 +79,13 @@ var myStorage = {
   }
 };
 
-var gloveBoxContents = undefined;
+const gloveBoxContents = undefined;
 ```
 
 # --solutions--
 
 ```js
-var myStorage = {
+const myStorage = {
   "car":{
     "inside":{
       "glove box":"maps",
@@ -95,5 +96,5 @@ var myStorage = {
     }
   }
 };
-var gloveBoxContents = myStorage.car.inside["glove box"];
+const gloveBoxContents = myStorage.car.inside["glove box"];
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md
index fb5d7d29a0a..447f7067b7f 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md
@@ -16,11 +16,12 @@ Tuttavia, puoi ancora usare la notazione a parentesi sulle proprietà dell'ogget
 Ecco un esempio di come usare la notazione a parentesi per leggere la proprietà di un oggetto:
 
 ```js
-var myObj = {
+const myObj = {
   "Space Name": "Kirk",
   "More Space": "Spock",
   "NoSpace": "USS Enterprise"
 };
+
 myObj["Space Name"];
 myObj['More Space'];
 myObj["NoSpace"];
@@ -78,26 +79,25 @@ assert(code.match(/testObj\s*?\[('|")[^'"]+\1\]/g).length > 1);
 
 ```js
 // Setup
-var testObj = {
+const testObj = {
   "an entree": "hamburger",
   "my side": "veggies",
   "the drink": "water"
 };
 
 // Only change code below this line
-
-var entreeValue = testObj;   // Change this line
-var drinkValue = testObj;    // Change this line
+const entreeValue = testObj;   // Change this line
+const drinkValue = testObj;    // Change this line
 ```
 
 # --solutions--
 
 ```js
-var testObj = {
+const testObj = {
   "an entree": "hamburger",
   "my side": "veggies",
   "the drink": "water"
 };
-var entreeValue = testObj["an entree"];
-var drinkValue = testObj['the drink'];
+const entreeValue = testObj["an entree"];
+const drinkValue = testObj['the drink'];
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md
index 1a145c00b9d..2f17b7f8822 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md
@@ -16,15 +16,17 @@ La notazione a punti è quella che usi quando conosci già il nome della proprie
 Di seguito è riportato un esempio di utilizzo della notazione a punti (`.`) per leggere la proprietà di un oggetto:
 
 ```js
-var myObj = {
+const myObj = {
   prop1: "val1",
   prop2: "val2"
 };
-var prop1val = myObj.prop1;
-var prop2val = myObj.prop2;
+
+const prop1val = myObj.prop1;
+const prop2val = myObj.prop2;
 ```
 
 `prop1val` ha il valore della stringa `val1` e `prop2val` ha il avere un valore della stringa `val2`.
+
 # --instructions--
 
 Leggi i valori delle proprietà di `testObj` utilizzando la notazione a punti. Imposta la variabile `hatValue` in modo che sia uguale alla proprietà `hat` dell'oggetto, e imposta la variabile `shirtValue` in modo che sia uguale alla proprietà `shirt` dell'oggetto.
@@ -73,27 +75,26 @@ assert(code.match(/testObj\.\w+/g).length > 1);
 
 ```js
 // Setup
-var testObj = {
+const testObj = {
   "hat": "ballcap",
   "shirt": "jersey",
   "shoes": "cleats"
 };
 
 // Only change code below this line
-
-var hatValue = testObj;      // Change this line
-var shirtValue = testObj;    // Change this line
+const hatValue = testObj;      // Change this line
+const shirtValue = testObj;    // Change this line
 ```
 
 # --solutions--
 
 ```js
-var testObj = {
+const testObj = {
   "hat": "ballcap",
   "shirt": "jersey",
   "shoes": "cleats"
 };
 
-var hatValue = testObj.hat;
-var shirtValue = testObj.shirt;
+const hatValue = testObj.hat;
+const shirtValue = testObj.shirt;
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md
index 7e48babe8ad..0a55b7ccb55 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md
@@ -14,11 +14,14 @@ Un altro uso della notazione a parentesi con gli oggetti è quello di accedere a
 Ecco un esempio di utilizzo di una variabile per accedere a una proprietà:
 
 ```js
-var dogs = {
-  Fido: "Mutt",  Hunter: "Doberman",  Snoopie: "Beagle"
+const dogs = {
+  Fido: "Mutt",
+  Hunter: "Doberman",
+  Snoopie: "Beagle"
 };
-var myDog = "Hunter";
-var myBreed = dogs[myDog];
+
+const myDog = "Hunter";
+const myBreed = dogs[myDog];
 console.log(myBreed);
 ```
 
@@ -27,14 +30,16 @@ La stringa `Doberman` sarà visualizzata nella console.
 Un altro modo per utilizzare questo concetto è quando il nome della proprietà viene ottenuto dinamicamente durante l'esecuzione del programma, come segue:
 
 ```js
-var someObj = {
+const someObj = {
   propName: "John"
 };
+
 function propPrefix(str) {
-  var s = "prop";
+  const s = "prop";
   return s + str;
 }
-var someProp = propPrefix("Name");
+
+const someProp = propPrefix("Name");
 console.log(someObj[someProp]);
 ```
 
@@ -96,26 +101,25 @@ if(typeof player !== "undefined"){(function(v){return v;})(player);}
 
 ```js
 // Setup
-var testObj = {
+const testObj = {
   12: "Namath",
   16: "Montana",
   19: "Unitas"
 };
 
 // Only change code below this line
-
-var playerNumber;       // Change this line
-var player = testObj;   // Change this line
+const playerNumber = 42;  // Change this line
+const player = testObj;   // Change this line
 ```
 
 # --solutions--
 
 ```js
-var testObj = {
+const testObj = {
   12: "Namath",
   16: "Montana",
   19: "Unitas"
 };
-var playerNumber = 16;
-var player = testObj[playerNumber];
+const playerNumber = 16;
+const player = testObj[playerNumber];
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md
index b7c1d3b39ed..e2c379658ed 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md
@@ -28,7 +28,7 @@ Ora quando valuteremo `ourDog.bark`, otterremo il suo abbaiare, `bow-wow`.
 Esempio:
 
 ```js
-var ourDog = {
+const ourDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
@@ -67,7 +67,7 @@ assert(!/bark[^\n]:/.test(code));
 ## --seed-contents--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
@@ -80,7 +80,7 @@ var myDog = {
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md
index db44754a406..5c51addbbfe 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md
@@ -18,7 +18,7 @@ JavaScript utilizza il simbolo `+` come operatore di addizione quando è posizio
 **Esempio:**
 
 ```js
-myVar = 5 + 10;
+const myVar = 5 + 10;
 ```
 
 `myVar` ora ha il valore `15`.
@@ -52,11 +52,11 @@ assert(/\+/.test(code));
 ## --seed-contents--
 
 ```js
-var sum = 10 + 0;
+const sum = 10 + 0;
 ```
 
 # --solutions--
 
 ```js
-var sum = 10 + 10;
+const sum = 10 + 10;
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md
index 29a1a0d95bb..601d3e6c715 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md
@@ -92,7 +92,7 @@ assert(code.match(/break/g).length > 2);
 
 ```js
 function switchOfStuff(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
 
@@ -108,7 +108,7 @@ switchOfStuff(1);
 
 ```js
 function switchOfStuff(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case "a":
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md
index 4ab02ac5abe..64d7c32aad7 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md
@@ -14,8 +14,8 @@ Proprio come possiamo costruire una stringa su più righe di stringhe <dfn>lette
 Esempio:
 
 ```js
-var anAdjective = "awesome!";
-var ourStr = "freeCodeCamp is ";
+const anAdjective = "awesome!";
+let ourStr = "freeCodeCamp is ";
 ourStr += anAdjective;
 ```
 
@@ -64,15 +64,14 @@ assert(code.match(/myStr\s*\+=\s*someAdjective\s*/).length > 0);
 
 ```js
 // Change code below this line
-
-var someAdjective;
-var myStr = "Learning to code is ";
+const someAdjective = "";
+let myStr = "Learning to code is ";
 ```
 
 # --solutions--
 
 ```js
-var someAdjective = "neat";
-var myStr = "Learning to code is ";
+const someAdjective = "neat";
+let myStr = "Learning to code is ";
 myStr += someAdjective;
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/assignment-with-a-returned-value.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/assignment-with-a-returned-value.md
index 7f5495e0fec..4a410f6d46f 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/assignment-with-a-returned-value.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/assignment-with-a-returned-value.md
@@ -49,13 +49,14 @@ assert(/processed\s*=\s*processArg\(\s*7\s*\)/.test(code));
 
 ```js
 // Setup
-var processed = 0;
+let processed = 0;
 
 function processArg(num) {
   return (num + 3) / 5;
 }
 
 // Only change code below this line
+
 ```
 
 # --solutions--
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md
index 7c2e39e0c59..2bc4084a847 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md
@@ -18,7 +18,7 @@ Gli oggetti sono utili per archiviare i dati in modo strutturato e possono rappr
 Ecco un esempio di oggetto gatto (cat):
 
 ```js
-var cat = {
+const cat = {
   "name": "Whiskers",
   "legs": 4,
   "tails": 1,
@@ -29,7 +29,7 @@ var cat = {
 In questo esempio, tutte le proprietà sono memorizzate come stringhe, come `name`, `legs`e `tails`. Per le proprietà puoi anche usare i numeri. Puoi anche omettere le virgolette per le proprietà di tipo stringa di una sola parola, come segue:
 
 ```js
-var anotherObject = {
+const anotherObject = {
   make: "Ford",
   5: "five",
   "model": "focus"
@@ -139,18 +139,18 @@ assert(
 ## --seed-contents--
 
 ```js
-var myDog = {
-// Only change code below this line
+const myDog = {
+  // Only change code below this line
 
 
-// Only change code above this line
+  // Only change code above this line
 };
 ```
 
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md
index c9c1eb08d1f..9751c1dc03d 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md
@@ -16,7 +16,7 @@ L'operatore di base è l'operatore di uguaglianza `==`. L'operatore di uguaglian
 ```js
 function equalityTest(myVal) {
   if (myVal == 10) {
-     return "Equal";
+    return "Equal";
   }
   return "Not Equal";
 }
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-inequality-operator.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-inequality-operator.md
index 048161809c8..7b8c7ea3174 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-inequality-operator.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-inequality-operator.md
@@ -25,7 +25,7 @@ Nell'ordine, queste espressioni saranno valutate `true`, `false`, `false`, `fals
 
 # --instructions--
 
-Aggiungi l'operatore di disuguaglianza `!=` nell'istruzione `if` in modo che la funzione restituisca la stringa `Not Equal` quando `val` non equivale a `99`
+Aggiungi l'operatore di disuguaglianza `!=` nella condizione dell' `if` in modo che la funzione restituisca la stringa `Not Equal` quando `val` non equivale a `99`.
 
 # --hints--
 
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-strict-equality-operator.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-strict-equality-operator.md
index eac103167e5..3107758b4db 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-strict-equality-operator.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-strict-equality-operator.md
@@ -26,7 +26,7 @@ Nel secondo esempio, `3` è un tipo `Number` e `'3'` è un tipo `String`.
 
 # --instructions--
 
-Usa l'operatore di uguaglianza stretta nell'istruzione `if` in modo che la funzione restituisca la stringa `Equal` quando `val` è strettamente uguale a `7`
+Usa l'operatore di uguaglianza stretta nella condizione dell'`if` in modo che la funzione restituisca la stringa `Equal` quando `val` è strettamente uguale a `7`.
 
 # --hints--
 
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md
index 3a7516605f8..4549ea2628c 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md
@@ -20,7 +20,7 @@ per aggiungere `5` a `myVar`. Poiché questo è uno scherma molto comune, ci son
 Uno di questi operatori è l'operatore `+=`.
 
 ```js
-var myVar = 1;
+let myVar = 1;
 myVar += 5;
 console.log(myVar);
 ```
@@ -61,9 +61,9 @@ Non dovresti modificare il codice sopra il commento specificato.
 
 ```js
 assert(
-  /var a = 3;/.test(code) &&
-    /var b = 17;/.test(code) &&
-    /var c = 12;/.test(code)
+  /let a = 3;/.test(code) &&
+    /let b = 17;/.test(code) &&
+    /let c = 12;/.test(code)
 );
 ```
 
@@ -78,9 +78,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 3;
-var b = 17;
-var c = 12;
+let a = 3;
+let b = 17;
+let c = 12;
 
 // Only change code below this line
 a = a + 12;
@@ -91,9 +91,9 @@ c = c + 7;
 # --solutions--
 
 ```js
-var a = 3;
-var b = 17;
-var c = 12;
+let a = 3;
+let b = 17;
+let c = 12;
 
 a += 12;
 b += 9;
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md
index b14acf94bfe..446a9a95641 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md
@@ -55,9 +55,9 @@ Non dovresti modificare il codice sopra il commento specificato.
 
 ```js
 assert(
-  /var a = 48;/.test(code) &&
-    /var b = 108;/.test(code) &&
-    /var c = 33;/.test(code)
+  /let a = 48;/.test(code) &&
+    /let b = 108;/.test(code) &&
+    /let c = 33;/.test(code)
 );
 ```
 
@@ -72,9 +72,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 48;
-var b = 108;
-var c = 33;
+let a = 48;
+let b = 108;
+let c = 33;
 
 // Only change code below this line
 a = a / 12;
@@ -85,9 +85,9 @@ c = c / 11;
 # --solutions--
 
 ```js
-var a = 48;
-var b = 108;
-var c = 33;
+let a = 48;
+let b = 108;
+let c = 33;
 
 a /= 12;
 b /= 4;
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md
index 6ba1434e327..5229214cda7 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md
@@ -55,9 +55,9 @@ Non dovresti modificare il codice sopra il commento specificato.
 
 ```js
 assert(
-  /var a = 5;/.test(code) &&
-    /var b = 12;/.test(code) &&
-    /var c = 4\.6;/.test(code)
+  /let a = 5;/.test(code) &&
+    /let b = 12;/.test(code) &&
+    /let c = 4\.6;/.test(code)
 );
 ```
 
@@ -72,9 +72,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 5;
-var b = 12;
-var c = 4.6;
+let a = 5;
+let b = 12;
+let c = 4.6;
 
 // Only change code below this line
 a = a * 5;
@@ -85,9 +85,9 @@ c = c * 10;
 # --solutions--
 
 ```js
-var a = 5;
-var b = 12;
-var c = 4.6;
+let a = 5;
+let b = 12;
+let c = 4.6;
 
 a *= 5;
 b *= 3;
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md
index 37aaeb515a2..9604a3105b2 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md
@@ -55,7 +55,7 @@ Non dovresti modificare il codice sopra il commento specificato.
 
 ```js
 assert(
-  /var a = 11;/.test(code) && /var b = 9;/.test(code) && /var c = 3;/.test(code)
+  /let a = 11;/.test(code) && /let b = 9;/.test(code) && /let c = 3;/.test(code)
 );
 ```
 
@@ -70,9 +70,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 11;
-var b = 9;
-var c = 3;
+let a = 11;
+let b = 9;
+let c = 3;
 
 // Only change code below this line
 a = a - 6;
@@ -83,9 +83,9 @@ c = c - 1;
 # --solutions--
 
 ```js
-var a = 11;
-var b = 9;
-var c = 3;
+let a = 11;
+let b = 9;
+let c = 3;
 
 a -= 6;
 b -= 15;
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-plus-operator.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-plus-operator.md
index 022391c2fa7..4d892a62d25 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-plus-operator.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-plus-operator.md
@@ -22,7 +22,7 @@ In JavaScript, quando l'operatore `+` viene usato con un valore di tipo `String`
 Esempio:
 
 ```js
-var ourStr = "I come first. " + "I come second.";
+const ourStr = "I come first. " + "I come second.";
 ```
 
 La stringa `I come first. I come second.` sarebbe visualizzata nella console.
@@ -44,10 +44,10 @@ Dovresti usare l'operatore `+` per costruire `myStr`.
 assert(code.match(/(["']).*\1\s*\+\s*(["']).*\2/g));
 ```
 
-`myStr` dovrebbe essere creato usando la parola chiave `var`.
+`myStr` dovrebbe essere creato usando la parola chiave `const`.
 
 ```js
-assert(/var\s+myStr/.test(code));
+assert(/const\s+myStr/.test(code));
 ```
 
 Dovresti assegnare il risultato alla variabile `myStr`.
@@ -73,11 +73,11 @@ assert(/myStr\s*=/.test(code));
 ## --seed-contents--
 
 ```js
-var myStr; // Change this line
+const myStr = ""; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var myStr = "This is the start. " + "This is the end.";
+const myStr = "This is the start. " + "This is the end.";
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md
index b8676edf8b8..9dbaaec1679 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md
@@ -16,7 +16,7 @@ Possiamo anche usare l'operatore `+=` per <dfn>concatenare</dfn> una stringa all
 Esempio:
 
 ```js
-var ourStr = "I come first. ";
+let ourStr = "I come first. ";
 ourStr += "I come second.";
 ```
 
@@ -57,14 +57,12 @@ assert(code.match(/myStr\s*\+=\s*(["']).*\1/g));
 ## --seed-contents--
 
 ```js
-// Only change code below this line
-
-var myStr;
+let myStr;
 ```
 
 # --solutions--
 
 ```js
-var myStr = "This is the first sentence. ";
+let myStr = "This is the first sentence. ";
 myStr += "This is the second sentence.";
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md
index 809fc93be2f..464e2e5b568 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md
@@ -14,8 +14,8 @@ A volte dovrai costruire una stringa, nello stile di [Mad Libs](https://en.wikip
 Esempio:
 
 ```js
-var ourName = "freeCodeCamp";
-var ourStr = "Hello, our name is " + ourName + ", how are you?";
+const ourName = "freeCodeCamp";
+const ourStr = "Hello, our name is " + ourName + ", how are you?";
 ```
 
 `ourStr` avrà un valore stringa `Hello, our name is freeCodeCamp, how are you?`.
@@ -63,13 +63,13 @@ assert(code.match(/["']\s*\+\s*myName\s*\+\s*["']/g).length > 0);
 
 ```js
 // Only change code below this line
-var myName;
-var myStr;
+const myName = "";
+const myStr = "";
 ```
 
 # --solutions--
 
 ```js
-var myName = "Bob";
-var myStr = "My name is " + myName + " and I am well!";
+const myName = "Bob";
+const myStr = "My name is " + myName + " and I am well!";
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/count-backwards-with-a-for-loop.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/count-backwards-with-a-for-loop.md
index 34f024419b4..fb9839f6032 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/count-backwards-with-a-for-loop.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/count-backwards-with-a-for-loop.md
@@ -16,13 +16,14 @@ Per decrementare di due ad ogni iterazione, dovremo cambiare la nostra inizializ
 Inizieremo da `i = 10` e ripeteremo finché `i > 0`. Diminuiremo `i` di 2 ad ogni ciclo con `i -= 2`.
 
 ```js
-var ourArray = [];
-for (var i = 10; i > 0; i -= 2) {
+const ourArray = [];
+
+for (let i = 10; i > 0; i -= 2) {
   ourArray.push(i);
 }
 ```
 
-`ourArray` adesso conterrà `[10,8,6,4,2]`. Cambiamo la nostra inizializzazione e espressione finale in modo da poter contare indietro di due per creare un array di numeri dispari discendenti.
+`ourArray` adesso conterrà `[10, 8, 6, 4, 2]`. Cambiamo la nostra inizializzazione e espressione finale in modo da poter contare indietro di due per creare un array di numeri dispari discendenti.
 
 # --instructions--
 
@@ -42,7 +43,7 @@ Dovresti usare il metodo array `push`.
 assert(code.match(/myArray.push/));
 ```
 
-`myArray` dovrebbe essere uguale a `[9,7,5,3,1]`.
+`myArray` dovrebbe essere uguale a `[9, 7, 5, 3, 1]`.
 
 ```js
 assert.deepEqual(myArray, [9, 7, 5, 3, 1]);
@@ -60,16 +61,17 @@ if(typeof myArray !== "undefined"){(function(){return myArray;})();}
 
 ```js
 // Setup
-var myArray = [];
+const myArray = [];
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myArray = [];
-for (var i = 9; i > 0; i -= 2) {
+const myArray = [];
+for (let i = 9; i > 0; i -= 2) {
   myArray.push(i);
 }
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md
index cf0e722a4bc..2b77d02d98e 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md
@@ -159,7 +159,7 @@ assert(
 ## --seed-contents--
 
 ```js
-var count = 0;
+let count = 0;
 
 function cc(card) {
   // Only change code below this line
@@ -175,7 +175,7 @@ cc(2); cc(3); cc(7); cc('K'); cc('A');
 # --solutions--
 
 ```js
-var count = 0;
+let count = 0;
 function cc(card) {
   switch(card) {
     case 2:
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md
index 936dfa05270..8e3efadda90 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md
@@ -42,13 +42,14 @@ assert(myDecimal % 1 != 0);
 ## --seed-contents--
 
 ```js
-var ourDecimal = 5.7;
+const ourDecimal = 5.7;
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myDecimal = 9.9;
+const myDecimal = 9.9;
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/declare-a-read-only-variable-with-the-const-keyword.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/declare-a-read-only-variable-with-the-const-keyword.md
index cca667f914e..4144ea4ceca 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/declare-a-read-only-variable-with-the-const-keyword.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/declare-a-read-only-variable-with-the-const-keyword.md
@@ -10,7 +10,7 @@ dashedName: declare-a-read-only-variable-with-the-const-keyword
 
 La parola chiave `let` non è l'unico nuovo modo per dichiarare le variabili. In ES6, puoi anche dichiarare variabili usando la parola chiave `const`.
 
-`const` ha tutte le fantastiche caratteristiche che ha `let`, con il il valore aggiunto che le variabili dichiarate utilizzando `const` sono di sola lettura. Esse sono un valore costante, il che significa che una volta assegnata una variabile con `const`, non può più essere riassegnata.
+`const` ha tutte le fantastiche caratteristiche che ha `let`, con il il valore aggiunto che le variabili dichiarate utilizzando `const` sono di sola lettura. Esse sono un valore costante, il che significa che una volta assegnata una variabile con `const`, non può più essere riassegnata:
 
 ```js
 const FAV_PET = "Cats";
@@ -19,9 +19,11 @@ FAV_PET = "Dogs";
 
 La console mostrerà un errore a causa della riassegnazione del valore di `FAV_PET`.
 
-Come puoi vedere, cercare di riassegnare una variabile dichiarata con `const` genererà un errore. Dovresti sempre dichiarare le variabili che non vuoi riassegnare usando la parola chiave `const`. Questo aiuta quando nel caso dovessi tentare accidentalmente di riassegnare il valore a una variabile che è destinata a rimanere costante. Una pratica comune quando si dà il nome alle costanti è usare tutte le lettere maiuscole, separando le parole con un underscore.
+Dovresti sempre dichiarare le variabili che non vuoi riassegnare usando la parola chiave `const`. Questo aiuta quando nel caso dovessi tentare accidentalmente di riassegnare il valore a una variabile che è destinata a rimanere costante.
 
-**Nota:** È pratica comune per gli sviluppatori usare identificatori di variabili a lettere maiuscole per valori immutabili e a lettere minuscole o camelCase per valori mutabili (oggetti e array). In una sfida successiva vedrai un esempio di identificatore di variabile con lettere minuscole utilizzato per un array.
+Una pratica comune quando si dà il nome alle costanti è usare tutte le lettere maiuscole, separando le parole con un underscore.
+
+**Nota:** È pratica comune per gli sviluppatori usare identificatori di variabili a lettere maiuscole per valori immutabili e a lettere minuscole o camelCase per valori mutabili (oggetti e array). Imparerai di più su oggetti, array, e valori mutabili e immutabili in sfide future. In sfide future vedrai esempi di identificatori di variavile in maiuscolo, minuscolo e camelCase.
 
 # --instructions--
 
@@ -35,23 +37,33 @@ Modifica il codice in modo che tutte le variabili siano dichiarate utilizzando `
 (getUserInput) => assert(!getUserInput('index').match(/var/g));
 ```
 
-`SENTENCE` dovrebbe essere una variabile costante dichiarata con `const`.
+Dovresti cambiare `fCC` a solo maiuscole.
 
 ```js
-(getUserInput) => assert(getUserInput('index').match(/(const SENTENCE)/g));
+(getUserInput) => {
+  assert(getUserInput('index').match(/(FCC)/));
+  assert(!getUserInput('index').match(/fCC/));
+}
 ```
 
-`i` dovrebbe essere dichiarata con `let`.
+`FCC` dovrebbe essere una variabile costante dichiarata con `const`.
 
 ```js
-(getUserInput) => assert(getUserInput('index').match(/(let i)/g));
+assert.equal(FCC, 'freeCodeCamp');
+assert.match(code, /const\s+FCC/);
 ```
 
-`console.log` dovrebbe essere cambiato per stampare la variabile `SENTENCE`.
+`fact` dovrebbe essere dichiarata con `let`.
+
+```js
+(getUserInput) => assert(getUserInput('index').match(/(let fact)/g));
+```
+
+`console.log` dovrebbe essere cambiato in modo da stampare le variabili `FCC` e `fact`.
 
 ```js
 (getUserInput) =>
-  assert(getUserInput('index').match(/console\.log\(\s*SENTENCE\s*\)\s*;?/g));
+  assert(getUserInput('index').match(/console\.log\(\s*FCC\s*\,\s*fact\s*\)\s*;?/g));
 ```
 
 # --seed--
@@ -59,31 +71,21 @@ Modifica il codice in modo che tutte le variabili siano dichiarate utilizzando `
 ## --seed-contents--
 
 ```js
-function printManyTimes(str) {
+// Only change code below this line
+var fCC = "freeCodeCamp";
+var fact = "is cool!";
+// Only change code above this line
 
-  // Only change code below this line
-
-  var sentence = str + " is cool!";
-  for (var i = 0; i < str.length; i+=2) {
-    console.log(sentence);
-  }
-
-  // Only change code above this line
-
-}
-printManyTimes("freeCodeCamp");
+fact = "is awesome!";
+console.log(fCC, fact);
 ```
 
 # --solutions--
 
 ```js
-function printManyTimes(str) {
+const FCC = "freeCodeCamp";
+let fact = "is cool!";
 
-  const SENTENCE = str + " is cool!";
-  for (let i = 0; i < str.length; i+=2) {
-    console.log(SENTENCE);
-  }
-
-}
-printManyTimes("freeCodeCamp");
+fact = "is awesome!";
+console.log(FCC, fact);
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/declare-string-variables.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/declare-string-variables.md
index 93851155f1c..21013359bce 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/declare-string-variables.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/declare-string-variables.md
@@ -9,13 +9,19 @@ dashedName: declare-string-variables
 
 # --description--
 
-Precedentemente abbiamo usato il codice
+In precedenza hai usato il seguente codice per dichiarare una variabile:
+
+```js
+var myName;
+```
+
+Ma puoi anche dichiarare una variabile con valore stringa in questo modo:
 
 ```js
 var myName = "your name";
 ```
 
-`"your name"` è chiamato una <dfn>stringa</dfn> <dfn>letterale</dfn>. È una stringa perché è una serie di zero o più caratteri racchiusi in virgolette singole o doppie.
+`"your name"` è chiamato una <dfn>stringa</dfn> <dfn>letterale</dfn>. Una stringa letterale, o stringa, è una serie di zero o più caratteri racchiusi in virgolette singole o doppie.
 
 # --instructions--
 
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md
index 0c047046522..75bd853e1f2 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md
@@ -39,7 +39,7 @@ assert(myVar === 10);
 
 ```js
 assert(
-  /var\s*myVar\s*=\s*11;\s*\/*.*\s*([-]{2}\s*myVar|myVar\s*[-]{2});/.test(code)
+  /let\s*myVar\s*=\s*11;\s*\/*.*\s*([-]{2}\s*myVar|myVar\s*[-]{2});/.test(code)
 );
 ```
 
@@ -52,7 +52,7 @@ assert(/[-]{2}\s*myVar|myVar\s*[-]{2}/.test(code));
 Non dovresti modificare il codice sopra il commento specificato.
 
 ```js
-assert(/var myVar = 11;/.test(code));
+assert(/let myVar = 11;/.test(code));
 ```
 
 # --seed--
@@ -66,7 +66,7 @@ assert(/var myVar = 11;/.test(code));
 ## --seed-contents--
 
 ```js
-var myVar = 11;
+let myVar = 11;
 
 // Only change code below this line
 myVar = myVar - 1;
@@ -75,6 +75,6 @@ myVar = myVar - 1;
 # --solutions--
 
 ```js
-var myVar = 11;
+let myVar = 11;
 myVar--;
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md
index 01b03808be6..1ab4e1e7ad1 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md
@@ -18,7 +18,7 @@ delete ourDog.bark;
 Esempio:
 
 ```js
-var ourDog = {
+const ourDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
@@ -70,7 +70,7 @@ assert(code.match(/"tails": 1/g).length > 0);
 
 ```js
 // Setup
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
@@ -79,12 +79,13 @@ var myDog = {
 };
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md
index 1cca4be92d7..ad30fcc1a9a 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md
@@ -46,11 +46,11 @@ assert(code.match(/quotient/g).length === 1);
 ## --seed-contents--
 
 ```js
-var quotient = 0.0 / 2.0; // Change this line
+const quotient = 0.0 / 2.0; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var quotient = 4.4 / 2.0;
+const quotient = 4.4 / 2.0;
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md
index 0240fb31119..0739cc32c25 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md
@@ -16,7 +16,7 @@ JavaScript utilizza il simbolo `/` per la divisione.
 **Esempio**
 
 ```js
-myVar = 16 / 2;
+const myVar = 16 / 2;
 ```
 
 `myVar` ora ha il valore `8`.
@@ -49,11 +49,11 @@ assert(/\d+\s*\/\s*\d+/.test(code));
 ## --seed-contents--
 
 ```js
-var quotient = 66 / 0;
+const quotient = 66 / 0;
 ```
 
 # --solutions--
 
 ```js
-var quotient = 66 / 33;
+const quotient = 66 / 33;
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md
index 98b4514870e..17aad98a65f 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md
@@ -89,11 +89,11 @@ console.log('myStr:\n' + myStr);}})();
 ## --seed-contents--
 
 ```js
-var myStr; // Change this line
+const myStr = ""; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var myStr = "FirstLine\n\t\\SecondLine\nThirdLine";
+const myStr = "FirstLine\n\t\\SecondLine\nThirdLine";
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md
index 8a7022ecf36..40fc3c28230 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md
@@ -14,7 +14,7 @@ Quando definisci una stringa devi cominciare e finire con una virgoletta singola
 In JavaScript, puoi fare l'<dfn>escape</dfn> di una virgoletta per distinguerla da quella usata per terminare la stringa posizionando una <dfn>barra rovesciata</dfn> (`\`) davanti alla virgoletta.
 
 ```js
-var sampleStr = "Alan said, \"Peter is learning JavaScript\".";
+const sampleStr = "Alan said, \"Peter is learning JavaScript\".";
 ```
 
 Questo segnala a JavaScript che la virgoletta seguente non è la fine della stringa, ma dovrebbe invece apparire dentro la stringa. Quindi se dovessi farla visualizzare nella console, otterresti:
@@ -62,11 +62,11 @@ assert(/I am a "double quoted" string inside "double quotes(\."|"\.)$/.test(mySt
 ## --seed-contents--
 
 ```js
-var myStr = ""; // Change this line
+const myStr = ""; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var myStr = "I am a \"double quoted\" string inside \"double quotes\".";
+const myStr = "I am a \"double quoted\" string inside \"double quotes\".";
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/explore-differences-between-the-var-and-let-keywords.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/explore-differences-between-the-var-and-let-keywords.md
index 9e5a126c03f..bc3fff3b865 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/explore-differences-between-the-var-and-let-keywords.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/explore-differences-between-the-var-and-let-keywords.md
@@ -8,32 +8,30 @@ dashedName: explore-differences-between-the-var-and-let-keywords
 
 # --description--
 
-Uno dei maggiori problemi quando si dichiarano delle variabili con la parola chiave `var` è che è possibile sovrascrivere le dichiarazioni delle variabili senza errori.
+Uno dei maggiori problemi quando si dichiarano delle variabili con la parola chiave `var` è che è possibile sovrascrivere facilmente le dichiarazioni delle variabili:
 
 ```js
-var camper = 'James';
-var camper = 'David';
+var camper = "James";
+var camper = "David";
 console.log(camper);
 ```
 
-Qui la console mostrerà la stringa `David`.
+Nel codice qui sopra, la variabile `camper` è originariamente dichiarata come `James` per poi essere sovrascritta con `David`. La console poi mostra la stringa `David`.
 
-Come puoi vedere nel codice qui sopra, la variabile `camper` è originariamente dichiarata come `James` per poi essere sovrascritta con `David`. In una piccola applicazione si potrebbe non incorrere in questo tipo di problema, ma quando il codice diventa più grande, potresti accidentalmente sovrascrivere una variabile che non hai intenzione di sovrascrivere. Poiché questo comportamento non lancia un errore, la ricerca e la correzione di bug diventa più difficile.  
-Una nuova parola chiave, chiamata `let`, è stata introdotta in ES6 per risolvere questo potenziale problema con la parola chiave `var`. Se dovessi sostituire `var` con `let` nelle dichiarazioni delle variabili nel codice sopra, il risultato sarebbe un errore.
+In una piccola applicazione, potresti non incorrere in questo tipo di problema. Ma man mano che il tuo codebase diventa più grande potresti accidentalmente sovrascrivere una variabile che non intendevi sovrascrivere. Poiché questo comportamento non da errore, cercare e sistemare bug diventa più difficile.
+
+Una parola chiave chiamata `let` è stata introdotta in ES6, un aggiornamento importante a JavaScript, per risolvere questo potenziale problema con la parola chiave `var`. Imparerai altre caratteristiche di ES6 in sfide future.
+
+Se sostituisci `var` con `let` nel codice qua sopra, risulta in un errore:
 
 ```js
-let camper = 'James';
-let camper = 'David';
+let camper = "James";
+let camper = "David";
 ```
 
-Questo errore può essere visto nella console del tuo browser. Quindi, a differenza di `var`, quando si utilizza `let`, una variabile con lo stesso nome può essere dichiarata solo una volta. Nota l'`"use strict"`. Questo abilita la Strict Mode (Modalità Rigorosa), che cattura gli errori di codifica comuni e le azioni "non sicure". Per esempio:
+L'errore può essere visto nella console del browser.
 
-```js
-"use strict";
-x = 3.14;
-```
-
-Questo mostrerà l'errore `x is not defined`.
+Quindi a differenza di `var`, wuando usi `let`, una variabile con lo stesso nome può essere dichiarata una sola volta.
 
 # --instructions--
 
@@ -53,10 +51,10 @@ Aggiorna il codice in modo che utilizzi solo la parola chiave `let`.
 assert(catName === 'Oliver');
 ```
 
-`quote` dovrebbe essere uguale alla stringa `Oliver says Meow!`
+`catSound` dovrebbe essere uguale alla stringa `Meow!`
 
 ```js
-assert(quote === 'Oliver says Meow!');
+assert(catSound === 'Meow!');
 ```
 
 # --seed--
@@ -64,28 +62,13 @@ assert(quote === 'Oliver says Meow!');
 ## --seed-contents--
 
 ```js
-var catName;
-var quote;
-function catTalk() {
-  "use strict";
-
-  catName = "Oliver";
-  quote = catName + " says Meow!";
-
-}
-catTalk();
+var catName = "Oliver";
+var catSound = "Meow!";
 ```
 
 # --solutions--
 
 ```js
-let catName;
-let quote;
-function catTalk() {
-  'use strict';
-
-  catName = 'Oliver';
-  quote = catName + ' says Meow!';
-}
-catTalk();
+let catName = "Oliver";
+let catSound = "Meow!";
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/find-the-length-of-a-string.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/find-the-length-of-a-string.md
index ccfc058a172..e590f6893db 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/find-the-length-of-a-string.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/find-the-length-of-a-string.md
@@ -17,7 +17,7 @@ console.log("Alan Peter".length);
 
 Il valore `10` sarà visualizzato nella console.
 
-Ad esempio, se avessimo creato una variabile `var firstName = "Ada"`, potremmo scoprire quanto è lunga la stringa `Ada` utilizzando la proprietà `firstName.length`.
+Ad esempio, se avessimo creato una variabile `const firstName = "Ada"`, potremmo scoprire quanto è lunga la stringa `Ada` utilizzando la proprietà `firstName.length`.
 
 # --instructions--
 
@@ -29,8 +29,8 @@ Non dovresti cambiare le dichiarazioni della variabile nella sezione `// Setup`.
 
 ```js
 assert(
-  code.match(/var lastNameLength = 0;/) &&
-    code.match(/var lastName = "Lovelace";/)
+  code.match(/let lastNameLength = 0;/) &&
+    code.match(/const lastName = "Lovelace";/)
 );
 ```
 
@@ -52,18 +52,17 @@ assert(code.match(/=\s*lastName\.length/g) && !code.match(/lastName\s*=\s*8/));
 
 ```js
 // Setup
-var lastNameLength = 0;
-var lastName = "Lovelace";
+let lastNameLength = 0;
+const lastName = "Lovelace";
 
 // Only change code below this line
-
 lastNameLength = lastName;
 ```
 
 # --solutions--
 
 ```js
-var lastNameLength = 0;
-var lastName = "Lovelace";
+let lastNameLength = 0;
+const lastName = "Lovelace";
 lastNameLength = lastName.length;
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md
index 5640d2122ba..5985a299242 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md
@@ -31,7 +31,7 @@ Imposta `remainder` pari al resto di `11` diviso per `3` utilizzando l'operatore
 La variabile `remainder` dovrebbe essere inizializzata
 
 ```js
-assert(/var\s+?remainder/.test(code));
+assert(/(const|let|var)\s+?remainder/.test(code));
 ```
 
 Il valore di `remainder` dovrebbe essere `2`
@@ -57,13 +57,11 @@ assert(/\s+?remainder\s*?=\s*?.*%.*;?/.test(code));
 ## --seed-contents--
 
 ```js
-// Only change code below this line
-
-var remainder;
+const remainder = 0;
 ```
 
 # --solutions--
 
 ```js
-var remainder =  11 % 3;
+const remainder = 11 % 3;
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/global-scope-and-functions.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/global-scope-and-functions.md
index 499da827e02..e662de1aade 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/global-scope-and-functions.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/global-scope-and-functions.md
@@ -11,13 +11,13 @@ dashedName: global-scope-and-functions
 
 In JavaScript, lo <dfn>scope</dfn> (campo di applicazione o ambito di visibilità) si riferisce alla visibilità delle variabili. Le variabili che sono definite al di fuori del blocco di una funzione hanno un campo di applicazione <dfn>globale</dfn>. Questo significa che possono essere viste ovunque nel tuo codice JavaScript.
 
-Le variabili che vengono dichiarate senza la parola chiave `var` vengono create automaticamente nell'ambito `global`. Questo può dare delle conseguenze indesiderate da un'altra parte nel tuo codice o quando si esegue nuovamente la funzione. Dovresti sempre dichiarare le tue variabili con `var`.
+Le variabili che vengono dichiarate senza la parola chiave `let` o la parola chiave `const` vengono create automaticamente nell'ambito `global`. Questo può dare delle conseguenze indesiderate da un'altra parte nel tuo codice o quando si esegue nuovamente la funzione. Dovresti sempre dichiarare le tue variabili con `let` o `const`.
 
 # --instructions--
 
-Usando `var`, dichiara una variabile globale denominata `myGlobal` al di fuori di qualsiasi funzione. Inizializzala con un valore di `10`.
+Usando `let` o `const`, dichiara una variabile globale denominata `myGlobal` al di fuori di qualsiasi funzione. Inizializzala con un valore di `10`.
 
-All'interno della funzione `fun1`, assegna `5` a `oopsGlobal` ***senza*** utilizzare la parola chiave `var`.
+All'interno della funzione `fun1`, assegna `5` a `oopsGlobal` ***senza*** utilizzare le parole chiave `let` o `const`.
 
 # --hints--
 
@@ -33,10 +33,10 @@ assert(typeof myGlobal != 'undefined');
 assert(myGlobal === 10);
 ```
 
-`myGlobal` dovrebbe essere dichiarata usando la parola chiave `var`
+`myGlobal` dovrebbe essere dichiarata usando la parola chiave `let` o `const`
 
 ```js
-assert(/var\s+myGlobal/.test(code));
+assert(/(let|const)\s+myGlobal/.test(code));
 ```
 
 `oopsGlobal` dovrebbe essere una variabile globale e avere un valore di `5`
@@ -109,7 +109,7 @@ function fun2() {
 # --solutions--
 
 ```js
-var myGlobal = 10;
+const myGlobal = 10;
 
 function fun1() {
   oopsGlobal = 5;
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md
index 852c88daa21..40cedbbfd81 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md
@@ -14,9 +14,10 @@ dashedName: global-vs--local-scope-in-functions
 In questo esempio:
 
 ```js
-var someVar = "Hat";
+const someVar = "Hat";
+
 function myFun() {
-  var someVar = "Head";
+  const someVar = "Head";
   return someVar;
 }
 ```
@@ -53,13 +54,11 @@ assert(/return outerWear/.test(code));
 
 ```js
 // Setup
-var outerWear = "T-Shirt";
+const outerWear = "T-Shirt";
 
 function myOutfit() {
   // Only change code below this line
 
-
-
   // Only change code above this line
   return outerWear;
 }
@@ -70,9 +69,9 @@ myOutfit();
 # --solutions--
 
 ```js
-var outerWear = "T-Shirt";
+const outerWear = "T-Shirt";
 function myOutfit() {
-  var outerWear = "sweater";
+  const outerWear = "sweater";
   return outerWear;
 }
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md
index ba3b91c6008..e74d90aeadd 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md
@@ -90,7 +90,8 @@ assert(golfScore(5, 9) === 'Go Home!');
 ## --seed-contents--
 
 ```js
-var names = ["Hole-in-one!", "Eagle", "Birdie", "Par", "Bogey", "Double Bogey", "Go Home!"];
+const names = ["Hole-in-one!", "Eagle", "Birdie", "Par", "Bogey", "Double Bogey", "Go Home!"];
+
 function golfScore(par, strokes) {
   // Only change code below this line
 
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md
index 8d0f9a7c1f9..435b92ad320 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md
@@ -39,7 +39,7 @@ Non dovresti utilizzare l'operatore di assegnazione.
 
 ```js
 assert(
-  /var\s*myVar\s*=\s*87;\s*\/*.*\s*([+]{2}\s*myVar|myVar\s*[+]{2});/.test(code)
+  /let\s*myVar\s*=\s*87;\s*\/*.*\s*([+]{2}\s*myVar|myVar\s*[+]{2});/.test(code)
 );
 ```
 
@@ -52,7 +52,7 @@ assert(/[+]{2}\s*myVar|myVar\s*[+]{2}/.test(code));
 Non dovresti cambiare il codice sopra il commento specificato.
 
 ```js
-assert(/var myVar = 87;/.test(code));
+assert(/let myVar = 87;/.test(code));
 ```
 
 # --seed--
@@ -66,7 +66,7 @@ assert(/var myVar = 87;/.test(code));
 ## --seed-contents--
 
 ```js
-var myVar = 87;
+let myVar = 87;
 
 // Only change code below this line
 myVar = myVar + 1;
@@ -75,6 +75,6 @@ myVar = myVar + 1;
 # --solutions--
 
 ```js
-var myVar = 87;
+let myVar = 87;
 myVar++;
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md
index 5a725a78ec8..640f3be83a4 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md
@@ -64,7 +64,7 @@ assert(testElse(10) === 'Bigger than 5');
 Non dovresti modificare il codice sopra o sotto i commenti specificati.
 
 ```js
-assert(/var result = "";/.test(code) && /return result;/.test(code));
+assert(/let result = "";/.test(code) && /return result;/.test(code));
 ```
 
 # --seed--
@@ -73,7 +73,7 @@ assert(/var result = "";/.test(code) && /return result;/.test(code));
 
 ```js
 function testElse(val) {
-  var result = "";
+  let result = "";
   // Only change code below this line
 
   if (val > 5) {
@@ -95,7 +95,7 @@ testElse(4);
 
 ```js
 function testElse(val) {
-  var result = "";
+  let result = "";
   if(val > 5) {
     result = "Bigger than 5";
   } else {
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-odd-numbers-with-a-for-loop.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-odd-numbers-with-a-for-loop.md
index 8da25783420..02f2ac569b1 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-odd-numbers-with-a-for-loop.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-odd-numbers-with-a-for-loop.md
@@ -14,13 +14,14 @@ I cicli for non devono necessariamente iterare un numero alla volta. Modificando
 Inizieremo da `i = 0` e ripeteremo il ciclo finché `i < 10`. Incrementeremo `i` di 2 ad ogni ciclo con `i += 2`.
 
 ```js
-var ourArray = [];
-for (var i = 0; i < 10; i += 2) {
+const ourArray = [];
+
+for (let i = 0; i < 10; i += 2) {
   ourArray.push(i);
 }
 ```
 
-`ourArray` ora conterrà `[0,2,4,6,8]`. Cambiamo la nostra `initialization` in modo da poter iterare sui numeri dispari.
+`ourArray` ora conterrà `[0, 2, 4, 6, 8]`. Cambiamo la nostra `initialization` in modo da poter iterare sui numeri dispari.
 
 # --instructions--
 
@@ -34,7 +35,7 @@ Dovresti usare un ciclo `for`.
 assert(/for\s*\([^)]+?\)/.test(code));
 ```
 
-`myArray` dovrebbe essere uguale a `[1,3,5,7,9]`.
+`myArray` dovrebbe essere uguale a `[1, 3, 5, 7, 9]`.
 
 ```js
 assert.deepEqual(myArray, [1, 3, 5, 7, 9]);
@@ -52,16 +53,17 @@ if(typeof myArray !== "undefined"){(function(){return myArray;})();}
 
 ```js
 // Setup
-var myArray = [];
+const myArray = [];
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myArray = [];
-for (var i = 1; i < 10; i += 2) {
+const myArray = [];
+for (let i = 1; i < 10; i += 2) {
   myArray.push(i);
 }
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md
index ab85b7eac84..5be90a8aae7 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md
@@ -12,8 +12,9 @@ dashedName: iterate-through-an-array-with-a-for-loop
 Un compito comune in JavaScript è quello di iterare attraverso i contenuti di un array. Un modo per farlo è con un ciclo `for`. Questo codice visualizzerà ogni elemento dell'array `arr` nella console:
 
 ```js
-var arr = [10, 9, 8, 7, 6];
-for (var i = 0; i < arr.length; i++) {
+const arr = [10, 9, 8, 7, 6];
+
+for (let i = 0; i < arr.length; i++) {
    console.log(arr[i]);
 }
 ```
@@ -62,18 +63,19 @@ assert(!__helpers.removeWhiteSpace(code).match(/total[=+-]0*[1-9]+/gm));
 
 ```js
 // Setup
-var myArr = [ 2, 3, 4, 5, 6];
+const myArr = [2, 3, 4, 5, 6];
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myArr = [ 2, 3, 4, 5, 6];
-var total = 0;
+const myArr = [2, 3, 4, 5, 6];
+let total = 0;
 
-for (var i = 0; i < myArr.length; i++) {
+for (let i = 0; i < myArr.length; i++) {
   total += myArr[i];
 }
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md
index 83c34501218..e55ddddf261 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md
@@ -12,8 +12,9 @@ dashedName: iterate-with-javascript-do---while-loops
 Il prossimo tipo di ciclo che vedremo si chiama `do...while`. Si chiama ciclo `do... while` perché prima eseguirà (`do`) un passaggio del codice all'interno del ciclo indipendentemente dalle condizioni, e poi continuerà ad eseguire il ciclo finché (`while`) la condizione specificata avrà valore `true`.
 
 ```js
-var ourArray = [];
-var i = 0;
+const ourArray = [];
+let i = 0;
+
 do {
   ourArray.push(i);
   i++;
@@ -23,8 +24,9 @@ do {
 L'esempio sopra si comporta come altri tipi di cicli, e l'array risultante sarà `[0, 1, 2, 3, 4]`. Tuttavia, ciò che rende il `do...while` diverso da altri cicli è come si comporta quando la condizione fallisce al primo controllo. Vediamolo in azione: ecco un normale ciclo `while` che eseguirà il codice nel ciclo finché `i < 5`:
 
 ```js
-var ourArray = []; 
-var i = 5;
+const ourArray = []; 
+let i = 5;
+
 while (i < 5) {
   ourArray.push(i);
   i++;
@@ -34,8 +36,9 @@ while (i < 5) {
 In questo esempio, inizializziamo il valore di `ourArray` a un array vuoto e il valore di `i` a 5. Quando eseguiamo il ciclo `while`, la condizione vale `false` perché `i` non è inferiore a 5, e in questo modo non eseguiremo il codice all'interno del ciclo. Il risultato è che `ourArray` finirà per non avere valori aggiunti, e sarà ancora simile a `[]` quando tutto il codice nell'esempio precedente sarà stato completato. Ora, dai un'occhiata a un ciclo `do...while`:
 
 ```js
-var ourArray = []; 
-var i = 5;
+const ourArray = []; 
+let i = 5;
+
 do {
   ourArray.push(i);
   i++;
@@ -80,8 +83,8 @@ if(typeof myArray !== "undefined"){(function(){return myArray;})();}
 
 ```js
 // Setup
-var myArray = [];
-var i = 10;
+const myArray = [];
+let i = 10;
 
 // Only change code below this line
 while (i < 5) {
@@ -93,8 +96,8 @@ while (i < 5) {
 # --solutions--
 
 ```js
-var myArray = [];
-var i = 10;
+const myArray = [];
+let i = 10;
 do {
   myArray.push(i);
   i++;
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-for-loops.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-for-loops.md
index 4ad581c2956..46a73d0507d 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-for-loops.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-for-loops.md
@@ -26,13 +26,14 @@ L'espressione finale è eseguita alla fine di ogni iterazione del ciclo, prima d
 Nell'esempio seguente inizializziamo con `i = 0` e iteriamo finché la nostra condizione `i < 5` è vera. Incrementeremo `i` di `1` ad ogni iterazione del ciclo con `i++` come espressione finale.
 
 ```js
-var ourArray = [];
-for (var i = 0; i < 5; i++) {
+const ourArray = [];
+
+for (let i = 0; i < 5; i++) {
   ourArray.push(i);
 }
 ```
 
-`ourArray` ha ora il valore `[0,1,2,3,4]`.
+`ourArray` ha ora il valore `[0, 1, 2, 3, 4]`.
 
 # --instructions--
 
@@ -46,7 +47,7 @@ Dovresti usare un ciclo `for`.
 assert(/for\s*\([^)]+?\)/.test(code));
 ```
 
-`myArray` dovrebbe essere uguale a `[1,2,3,4,5]`.
+`myArray` dovrebbe essere uguale a `[1, 2, 3, 4, 5]`.
 
 ```js
 assert.deepEqual(myArray, [1, 2, 3, 4, 5]);
@@ -64,16 +65,17 @@ if (typeof myArray !== "undefined"){(function(){return myArray;})();}
 
 ```js
 // Setup
-var myArray = [];
+const myArray = [];
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myArray = [];
-for (var i = 1; i < 6; i++) {
+const myArray = [];
+for (let i = 1; i < 6; i++) {
   myArray.push(i);
 }
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-while-loops.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-while-loops.md
index 266673087dc..0aa2bb494ee 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-while-loops.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-while-loops.md
@@ -14,9 +14,10 @@ dashedName: iterate-with-javascript-while-loops
 Il primo tipo di ciclo che vedremo è chiamato un ciclo `while` perché viene eseguito finché (while) una condizione specificata è vera e si arresta una volta che la condizione non è più vera.
 
 ```js
-var ourArray = [];
-var i = 0;
-while(i < 5) {
+const ourArray = [];
+let i = 0;
+
+while (i < 5) {
   ourArray.push(i);
   i++;
 }
@@ -38,7 +39,7 @@ Dovresti usare un ciclo `while`.
 assert(code.match(/while/g));
 ```
 
-`myArray` dovrebbe essere uguale a `[5,4,3,2,1,0]`.
+`myArray` dovrebbe essere uguale a `[5, 4, 3, 2, 1, 0]`.
 
 ```js
 assert.deepEqual(myArray, [5, 4, 3, 2, 1, 0]);
@@ -56,17 +57,18 @@ if(typeof myArray !== "undefined"){(function(){return myArray;})();}
 
 ```js
 // Setup
-var myArray = [];
+const myArray = [];
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myArray = [];
-var i = 5;
-while(i >= 0) {
+const myArray = [];
+let i = 5;
+while (i >= 0) {
   myArray.push(i);
   i--;
 }
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md
index cd289d6d2e2..49cc50547e8 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md
@@ -15,9 +15,10 @@ Ecco una funzione `myTest` con una variabile locale chiamata `loc`.
 
 ```js
 function myTest() {
-  var loc = "foo";
+  const loc = "foo";
   console.log(loc);
 }
+
 myTest();
 console.log(loc);
 ```
@@ -38,6 +39,7 @@ Il codice non dovrebbe contenere una variabile globale `myVar`.
 function declared() {
   myVar;
 }
+
 assert.throws(declared, ReferenceError);
 ```
 
@@ -57,7 +59,6 @@ assert(
 
 ```js
 function myLocalScope() {
-
   // Only change code below this line
 
   console.log('inside myLocalScope', myVar);
@@ -73,9 +74,8 @@ console.log('outside myLocalScope', myVar);
 
 ```js
 function myLocalScope() {
-
   // Only change code below this line
-  var myVar;
+  let myVar;
   console.log('inside myLocalScope', myVar);
 }
 myLocalScope();
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-pop.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-pop.md
index c1e3d5b8e9d..1b84fa86708 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-pop.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-pop.md
@@ -16,8 +16,8 @@ Un altro modo per cambiare i dati in un array è con la funzione `.pop()`.
 Qualsiasi tipo di elemento può essere estratto da un array - numeri, stringhe, anche array annidati.
 
 ```js
-var threeArr = [1, 4, 6];
-var oneDown = threeArr.pop();
+const threeArr = [1, 4, 6];
+const oneDown = threeArr.pop();
 console.log(oneDown);
 console.log(threeArr);
 ```
@@ -26,7 +26,7 @@ Il primo `console.log` mostrerà il valore `6`e il secondo mostrerà il valore `
 
 # --instructions--
 
-Utilizza la funzione `.pop()` per rimuovere l'ultimo elemento da `myArray`, assegnando il valore estratto a `removedFromMyArray`.
+Utilizza la funzione `.pop()` per rimuovere l'ultimo elemento da `myArray` e assegna il valore estratto a `removedFromMyArray`.
 
 # --hints--
 
@@ -69,22 +69,22 @@ assert(
 ## --after-user-code--
 
 ```js
-(function(y, z){return 'myArray = ' + JSON.stringify(y) + ' & removedFromMyArray = ' + JSON.stringify(z);})(myArray, removedFromMyArray);
+if (typeof removedFromMyArray !== 'undefined') (function(y, z){return 'myArray = ' + JSON.stringify(y) + ' & removedFromMyArray = ' + JSON.stringify(z);})(myArray, removedFromMyArray);
 ```
 
 ## --seed-contents--
 
 ```js
 // Setup
-var myArray = [["John", 23], ["cat", 2]];
+const myArray = [["John", 23], ["cat", 2]];
 
 // Only change code below this line
-var removedFromMyArray;
+
 ```
 
 # --solutions--
 
 ```js
-var myArray = [["John", 23], ["cat", 2]];
-var removedFromMyArray = myArray.pop();
+const myArray = [["John", 23], ["cat", 2]];
+const removedFromMyArray = myArray.pop();
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md
index a09fe87259d..f1ffde2dfb4 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md
@@ -16,10 +16,10 @@ Un modo semplice per aggiungere dei dati alla fine di un array è tramite la fun
 Esempi:
 
 ```js
-var arr1 = [1,2,3];
+const arr1 = [1, 2, 3];
 arr1.push(4);
 
-var arr2 = ["Stimpson", "J", "cat"];
+const arr2 = ["Stimpson", "J", "cat"];
 arr2.push(["happy", "joy"]);
 ```
 
@@ -64,14 +64,15 @@ assert(
 
 ```js
 // Setup
-var myArray = [["John", 23], ["cat", 2]];
+const myArray = [["John", 23], ["cat", 2]];
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myArray = [["John", 23], ["cat", 2]];
+const myArray = [["John", 23], ["cat", 2]];
 myArray.push(["dog",3]);
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-shift.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-shift.md
index 6486d361e58..302b952f496 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-shift.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-shift.md
@@ -16,15 +16,15 @@ dashedName: manipulate-arrays-with-shift
 Esempio:
 
 ```js
-var ourArray = ["Stimpson", "J", ["cat"]];
-var removedFromOurArray = ourArray.shift();
+const ourArray = ["Stimpson", "J", ["cat"]];
+const removedFromOurArray = ourArray.shift();
 ```
 
 `removedFromOurArray` dovrebbe avere un valore stringa `Stimpson`e `ourArray` dovrebbe valere `["J", ["cat"]]`.
 
 # --instructions--
 
-Utilizza la funzione `.shift()` per rimuovere il primo elemento da `myArray`, assegnando il valore "spostato" a `removedFromMyArray`.
+Utilizza la funzione `.shift()` per rimuovere il primo elemento da `myArray` e assegna il valore estratto a `removedFromMyArray`.
 
 # --hints--
 
@@ -65,24 +65,24 @@ assert(
 ## --after-user-code--
 
 ```js
-(function(y, z){return 'myArray = ' + JSON.stringify(y) + ' & removedFromMyArray = ' + JSON.stringify(z);})(myArray, removedFromMyArray);
+if (typeof removedFromMyArray !== 'undefined') (function(y, z){return 'myArray = ' + JSON.stringify(y) + ' & removedFromMyArray = ' + JSON.stringify(z);})(myArray, removedFromMyArray);
 ```
 
 ## --seed-contents--
 
 ```js
 // Setup
-var myArray = [["John", 23], ["dog", 3]];
+const myArray = [["John", 23], ["dog", 3]];
 
 // Only change code below this line
-var removedFromMyArray;
+
 ```
 
 # --solutions--
 
 ```js
-var myArray = [["John", 23], ["dog", 3]];
+const myArray = [["John", 23], ["dog", 3]];
 
 // Only change code below this line
-var removedFromMyArray = myArray.shift();
+const removedFromMyArray = myArray.shift();
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-unshift.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-unshift.md
index 63437d2bd29..9eded38dad0 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-unshift.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-unshift.md
@@ -16,7 +16,7 @@ Non puoi solo fare uno `shift` di elementi dall'inizio di un array: puoi anche f
 Esempio:
 
 ```js
-var ourArray = ["Stimpson", "J", "cat"];
+const ourArray = ["Stimpson", "J", "cat"];
 ourArray.shift();
 ourArray.unshift("Happy");
 ```
@@ -25,7 +25,7 @@ Dopo lo `shift`, `ourArray` avrà il valore `["J", "cat"]`. Dopo l'`unshift`, `o
 
 # --instructions--
 
-Aggiungi `["Paul",35]` all'inizio della variabile `myArray` usando `unshift()`.
+Aggiungi `["Paul", 35]` all'inizio della variabile `myArray` usando `unshift()`.
 
 # --hints--
 
@@ -63,16 +63,17 @@ assert(
 
 ```js
 // Setup
-var myArray = [["John", 23], ["dog", 3]];
+const myArray = [["John", 23], ["dog", 3]];
 myArray.shift();
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myArray = [["John", 23], ["dog", 3]];
+const myArray = [["John", 23], ["dog", 3]];
 myArray.shift();
 myArray.unshift(["Paul", 35]);
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md
index 7dc5e34fffa..ee2a3f97b13 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md
@@ -14,7 +14,7 @@ A volte potresti voler memorizzare i dati in una <dfn>struttura di dati</dfn> fl
 Ecco un esempio di struttura di dati complessa:
 
 ```js
-var ourMusic = [
+const ourMusic = [
   {
     "artist": "Daft Punk",
     "title": "Homework",
@@ -135,7 +135,7 @@ myMusic.forEach(object => {
 ## --seed-contents--
 
 ```js
-var myMusic = [
+const myMusic = [
   {
     "artist": "Billy Joel",
     "title": "Piano Man",
@@ -153,7 +153,7 @@ var myMusic = [
 # --solutions--
 
 ```js
-var myMusic = [
+const myMusic = [
   {
     "artist": "Billy Joel",
     "title": "Piano Man",
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/modify-array-data-with-indexes.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/modify-array-data-with-indexes.md
index e1d60237943..f88063fda3d 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/modify-array-data-with-indexes.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/modify-array-data-with-indexes.md
@@ -9,12 +9,12 @@ dashedName: modify-array-data-with-indexes
 
 # --description--
 
-A differenza delle stringhe, gli elementi degli array sono <dfn>mutabili</dfn> e possono essere cambiati liberamente.
+A differenza delle stringhe, gli elementi degli array sono <dfn>mutabili</dfn> e possono essere cambiati liberamente, anche se l'array è stato dichiarato con `const`.
 
 **Esempio**
 
 ```js
-var ourArray = [50,40,30];
+const ourArray = [50, 40, 30];
 ourArray[0] = 15;
 ```
 
@@ -28,7 +28,7 @@ Modificare i dati memorizzati all'indice `0` di `myArray` a un valore di `45`.
 
 # --hints--
 
-`myArray` dovrebbe ora essere `[45,64,99]`.
+`myArray` dovrebbe ora essere `[45, 64, 99]`.
 
 ```js
 assert(
@@ -73,14 +73,15 @@ if(typeof myArray !== "undefined"){(function(){return myArray;})();}
 
 ```js
 // Setup
-var myArray = [18,64,99];
+const myArray = [18, 64, 99];
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myArray = [18,64,99];
+const myArray = [18, 64, 99];
 myArray[0] = 45;
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md
index 91ee911e174..75ac5877718 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md
@@ -12,7 +12,7 @@ dashedName: multiple-identical-options-in-switch-statements
 Se l'istruzione `break` viene omessa da un'istruzione `switch` e in particolare da un suo `case`, le istruzione `case` successive sono eseguite fino a quando non si incontra un `break`. Se hai diversi input con lo stesso output, potrai rappresentarli in un'istruzione `switch` come la seguente:
 
 ```js
-var result = "";
+let result = "";
 switch(val) {
   case 1:
   case 2:
@@ -109,7 +109,7 @@ assert(code.match(/case/g).length === 9);
 
 ```js
 function sequentialSizes(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
 
@@ -125,7 +125,7 @@ sequentialSizes(1);
 
 ```js
 function sequentialSizes(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case 1:
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md
index 0154e925e8f..ba1c14e1054 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md
@@ -42,11 +42,11 @@ assert(/\*/.test(code));
 ## --seed-contents--
 
 ```js
-var product = 2.0 * 0.0;
+const product = 2.0 * 0.0;
 ```
 
 # --solutions--
 
 ```js
-var product = 2.0 * 2.5;
+const product = 2.0 * 2.5;
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md
index 9f835224361..4895a754e9e 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md
@@ -16,7 +16,7 @@ JavaScript utilizza il simbolo `*` per la moltiplicazione di due numeri.
 **Esempio**
 
 ```js
-myVar = 13 * 13;
+const myVar = 13 * 13;
 ```
 
 `myVar` dovrebbe avere il valore `169`.
@@ -50,11 +50,11 @@ assert(/\*/.test(code));
 ## --seed-contents--
 
 ```js
-var product = 8 * 0;
+const product = 8 * 0;
 ```
 
 # --solutions--
 
 ```js
-var product = 8 * 10;
+const product = 8 * 10;
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md
index 63ca252c752..a0d376d9741 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md
@@ -12,7 +12,7 @@ dashedName: nest-one-array-within-another-array
 È anche possibile nidificare array all'interno di altri array, come nell'esempio:
 
 ```js
-[["Bulls", 23], ["White Sox", 45]]
+const teams = [["Bulls", 23], ["White Sox", 45]];
 ```
 
 Questo viene anche chiamato un <dfn>array multidimensionale</dfn>.
@@ -41,11 +41,11 @@ if(typeof myArray !== "undefined"){(function(){return myArray;})();}
 
 ```js
 // Only change code below this line
-var myArray = [];
+const myArray = [];
 ```
 
 # --solutions--
 
 ```js
-var myArray = [[1,2,3]];
+const myArray = [[1, 2, 3]];
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/nesting-for-loops.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/nesting-for-loops.md
index c098d946a58..111d183e81b 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/nesting-for-loops.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/nesting-for-loops.md
@@ -12,11 +12,12 @@ dashedName: nesting-for-loops
 Se disponi di un array multidimensionale, è possibile utilizzare la stessa logica del punto precedente per iterare sia attraverso l'array che attraverso i suoi sottoarray. Ecco un esempio:
 
 ```js
-var arr = [
-  [1,2], [3,4], [5,6]
+const arr = [
+  [1, 2], [3, 4], [5, 6]
 ];
-for (var i=0; i < arr.length; i++) {
-  for (var j=0; j < arr[i].length; j++) {
+
+for (let i = 0; i < arr.length; i++) {
+  for (let j = 0; j < arr[i].length; j++) {
     console.log(arr[i][j]);
   }
 }
@@ -30,13 +31,13 @@ Modifica la funzione `multiplyAll` in modo che restituisca il prodotto di tutti
 
 # --hints--
 
-`multiplyAll([[1],[2],[3]])` dovrebbe restituire `6`
+`multiplyAll([[1], [2], [3]])` dovrebbe restituire `6`
 
 ```js
 assert(multiplyAll([[1], [2], [3]]) === 6);
 ```
 
-`multiplyAll([[1,2],[3,4],[5,6,7]])` dovrebbe restituire `5040`
+`multiplyAll([[1, 2], [3, 4], [5, 6, 7]])` dovrebbe restituire `5040`
 
 ```js
 assert(
@@ -48,7 +49,7 @@ assert(
 );
 ```
 
-`multiplyAll([[5,1],[0.2, 4, 0.5],[3, 9]])` dovrebbe restituire `54`
+`multiplyAll([[5, 1], [0.2, 4, 0.5], [3, 9]])` dovrebbe restituire `54`
 
 ```js
 assert(
@@ -66,28 +67,26 @@ assert(
 
 ```js
 function multiplyAll(arr) {
-  var product = 1;
+  let product = 1;
   // Only change code below this line
 
   // Only change code above this line
   return product;
 }
 
-multiplyAll([[1,2],[3,4],[5,6,7]]);
+multiplyAll([[1, 2], [3, 4], [5, 6, 7]]);
 ```
 
 # --solutions--
 
 ```js
 function multiplyAll(arr) {
-  var product = 1;
-  for (var i = 0; i < arr.length; i++) {
-    for (var j = 0; j < arr[i].length; j++) {
+  let product = 1;
+  for (let i = 0; i < arr.length; i++) {
+    for (let j = 0; j < arr[i].length; j++) {
       product *= arr[i][j];
     }
   }
   return product;
 }
-
-multiplyAll([[1,2],[3,4],[5,6,7]]);
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md
index ee07d56f521..f4955a3dd1e 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md
@@ -68,34 +68,33 @@ assert(lookUpProfile('Akira', 'address') === 'No such property');
 
 ```js
 // Setup
-var contacts = [
-    {
-        "firstName": "Akira",
-        "lastName": "Laine",
-        "number": "0543236543",
-        "likes": ["Pizza", "Coding", "Brownie Points"]
-    },
-    {
-        "firstName": "Harry",
-        "lastName": "Potter",
-        "number": "0994372684",
-        "likes": ["Hogwarts", "Magic", "Hagrid"]
-    },
-    {
-        "firstName": "Sherlock",
-        "lastName": "Holmes",
-        "number": "0487345643",
-        "likes": ["Intriguing Cases", "Violin"]
-    },
-    {
-        "firstName": "Kristian",
-        "lastName": "Vos",
-        "number": "unknown",
-        "likes": ["JavaScript", "Gaming", "Foxes"]
-    }
+const contacts = [
+  {
+    firstName: "Akira",
+    lastName: "Laine",
+    number: "0543236543",
+    likes: ["Pizza", "Coding", "Brownie Points"],
+  },
+  {
+    firstName: "Harry",
+    lastName: "Potter",
+    number: "0994372684",
+    likes: ["Hogwarts", "Magic", "Hagrid"],
+  },
+  {
+    firstName: "Sherlock",
+    lastName: "Holmes",
+    number: "0487345643",
+    likes: ["Intriguing Cases", "Violin"],
+  },
+  {
+    firstName: "Kristian",
+    lastName: "Vos",
+    number: "unknown",
+    likes: ["JavaScript", "Gaming", "Foxes"],
+  },
 ];
 
-
 function lookUpProfile(name, prop) {
   // Only change code below this line
 
@@ -108,44 +107,38 @@ lookUpProfile("Akira", "likes");
 # --solutions--
 
 ```js
-var contacts = [
-    {
-        "firstName": "Akira",
-        "lastName": "Laine",
-        "number": "0543236543",
-        "likes": ["Pizza", "Coding", "Brownie Points"]
-    },
-    {
-        "firstName": "Harry",
-        "lastName": "Potter",
-        "number": "0994372684",
-        "likes": ["Hogwarts", "Magic", "Hagrid"]
-    },
-    {
-        "firstName": "Sherlock",
-        "lastName": "Holmes",
-        "number": "0487345643",
-        "likes": ["Intriguing Cases", "Violin"]
-    },
-    {
-        "firstName": "Kristian",
-        "lastName": "Vos",
-        "number": "unknown",
-        "likes": ["JavaScript", "Gaming", "Foxes"]
-    },
+const contacts = [
+  {
+    firstName: "Akira",
+    lastName: "Laine",
+    number: "0543236543",
+    likes: ["Pizza", "Coding", "Brownie Points"],
+  },
+  {
+    firstName: "Harry",
+    lastName: "Potter",
+    number: "0994372684",
+    likes: ["Hogwarts", "Magic", "Hagrid"],
+  },
+  {
+    firstName: "Sherlock",
+    lastName: "Holmes",
+    number: "0487345643",
+    likes: ["Intriguing Cases", "Violin"],
+  },
+  {
+    firstName: "Kristian",
+    lastName: "Vos",
+    number: "unknown",
+    likes: ["JavaScript", "Gaming", "Foxes"],
+  },
 ];
-
-
-//Write your function in between these comments
-function lookUpProfile(name, prop){
-    for(var i in contacts){
-      if(contacts[i].firstName === name) {
-        return contacts[i][prop] || "No such property";
-      }
+function lookUpProfile(name, prop) {
+  for (let i in contacts) {
+    if (contacts[i].firstName === name) {
+      return contacts[i][prop] || "No such property";
     }
-   return "No such contact";
+  }
+  return "No such contact";
 }
-//Write your function in between these comments
-
-lookUpProfile("Akira", "likes");
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md
index 4bfd19ae6cd..5f9caec414f 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md
@@ -12,21 +12,21 @@ dashedName: quoting-strings-with-single-quotes
 I valori <dfn>Stringa</dfn> in JavaScript possono essere scritti con virgolette singole o doppie, purché si inizi e si termini con lo stesso tipo di virgolette. A differenza di alcuni altri linguaggi di programmazione, le virgolette singole e doppie funzionano allo stesso modo in JavaScript.
 
 ```js
-doubleQuoteStr = "This is a string"; 
-singleQuoteStr = 'This is also a string';
+const doubleQuoteStr = "This is a string"; 
+const singleQuoteStr = 'This is also a string';
 ```
 
 Il motivo per cui potresti voler usare un tipo di virgolette piuttosto dell'altro è se volessi usare entrambi in una stringa. Questo potrebbe accadere volendo salvare una conversazione in una stringa e avendo la conversazione tra virgolette. Un altro uso sarebbe salvare un tag `<a>` con vari attributi tra virgolette, tutto all'interno di una stringa.
 
 ```js
-conversation = 'Finn exclaims to Jake, "Algebraic!"';
+const conversation = 'Finn exclaims to Jake, "Algebraic!"';
 ```
 
 Tuttavia, questo diventa un problema se è necessario utilizzare le virgolette più esterne al suo interno. Ricorda, una stringa ha lo stesso tipo di virgolette all'inizio e alla fine. Ma se hai la stessa virgoletta da qualche parte nel mezzo, la stringa si fermerà anzitempo e lancerà un errore.
 
 ```js
-goodStr = 'Jake asks Finn, "Hey, let\'s go on an adventure?"'; 
-badStr = 'Finn responds, "Let's go!"';
+const goodStr = 'Jake asks Finn, "Hey, let\'s go on an adventure?"'; 
+const badStr = 'Finn responds, "Let's go!"';
 ```
 
 Qui `badStr` genererà un errore.
@@ -71,11 +71,11 @@ assert(code.match(/"/g).length === 4 && code.match(/'/g).length === 2);
 ## --seed-contents--
 
 ```js
-var myStr = "<a href=\"http://www.example.com\" target=\"_blank\">Link</a>";
+const myStr = "<a href=\"http://www.example.com\" target=\"_blank\">Link</a>";
 ```
 
 # --solutions--
 
 ```js
-var myStr = '<a href="http://www.example.com" target="_blank">Link</a>';
+const myStr = '<a href="http://www.example.com" target="_blank">Link</a>';
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md
index 3614886d35b..12a7b5a260f 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md
@@ -115,7 +115,7 @@ const _recordCollection = {
 
 ```js
 // Setup
-var recordCollection = {
+const recordCollection = {
   2548: {
     albumTitle: 'Slippery When Wet',
     artist: 'Bon Jovi',
@@ -146,7 +146,7 @@ updateRecords(recordCollection, 5439, 'artist', 'ABBA');
 # --solutions--
 
 ```js
-var recordCollection = {
+const recordCollection = {
   2548: {
     albumTitle: 'Slippery When Wet',
     artist: 'Bon Jovi',
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md
index 33bba64de84..a4299082318 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md
@@ -14,9 +14,9 @@ La ricorsione è il concetto che una funzione può essere espressa in termini di
 
 ```js
   function multiply(arr, n) {
-    var product = 1;
-    for (var i = 0; i < n; i++) {
-        product *= arr[i];
+    let product = 1;
+    for (let i = 0; i < n; i++) {
+      product *= arr[i];
     }
     return product;
   }
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md
index 6db6c8ebfc0..0495ccbb344 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md
@@ -108,7 +108,7 @@ assert(chainToSwitch(156) === '');
 
 ```js
 function chainToSwitch(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
   if (val === "bob") {
@@ -134,7 +134,7 @@ chainToSwitch(7);
 
 ```js
 function chainToSwitch(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case "bob":
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md
index 3ef69cfb90f..a00a5893cbf 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md
@@ -17,7 +17,8 @@ Possiamo passare dei valori a una funzione con gli <dfn>argomenti</dfn>. È poss
 function plusThree(num) {
   return num + 3;
 }
-var answer = plusThree(5);
+
+const answer = plusThree(5);
 ```
 
 `answer` ha il valore `8`.
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/return-early-pattern-for-functions.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/return-early-pattern-for-functions.md
index bfab0e5bbe4..102f744000b 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/return-early-pattern-for-functions.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/return-early-pattern-for-functions.md
@@ -33,43 +33,43 @@ Ricorda che [`undefined` è una parola chiave](https://www.freecodecamp.org/lear
 
 # --hints--
 
-`abTest(2,2)` dovrebbe restituire un numero
+`abTest(2, 2)` dovrebbe restituire un numero
 
 ```js
 assert(typeof abTest(2, 2) === 'number');
 ```
 
-`abTest(2,2)` dovrebbe restituire `8`
+`abTest(2, 2)` dovrebbe restituire `8`
 
 ```js
 assert(abTest(2, 2) === 8);
 ```
 
-`abTest(-2,2)` dovrebbe restituire `undefined`
+`abTest(-2, 2)` dovrebbe restituire `undefined`
 
 ```js
 assert(abTest(-2, 2) === undefined);
 ```
 
-`abTest(2,-2)` dovrebbe restituire `undefined`
+`abTest(2, -2)` dovrebbe restituire `undefined`
 
 ```js
 assert(abTest(2, -2) === undefined);
 ```
 
-`abTest(2,8)` dovrebbe restituire `18`
+`abTest(2, 8)` dovrebbe restituire `18`
 
 ```js
 assert(abTest(2, 8) === 18);
 ```
 
-`abTest(3,3)` dovrebbe restituire `12`
+`abTest(3, 3)` dovrebbe restituire `12`
 
 ```js
 assert(abTest(3, 3) === 12);
 ```
 
-`abTest(0,0)` dovrebbe restituire `0`
+`abTest(0, 0)` dovrebbe restituire `0`
 
 ```js
 assert(abTest(0, 0) === 0);
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/returning-boolean-values-from-functions.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/returning-boolean-values-from-functions.md
index 661409438e7..7f4c3d06b4f 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/returning-boolean-values-from-functions.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/returning-boolean-values-from-functions.md
@@ -14,7 +14,7 @@ dashedName: returning-boolean-values-from-functions
 A volte le persone usano un'istruzione `if/else` per fare un confronto, in questo modo:
 
 ```js
-function isEqual(a,b) {
+function isEqual(a, b) {
   if (a === b) {
     return true;
   } else {
@@ -26,7 +26,7 @@ function isEqual(a,b) {
 Ma c'è un modo migliore per farlo. Dal momento che `===` restituisce `true` o `false`, possiamo restituire il risultato del confronto:
 
 ```js
-function isEqual(a,b) {
+function isEqual(a, b) {
   return a === b;
 }
 ```
@@ -37,13 +37,13 @@ Correggi la funzione `isLess` per rimuovere le istruzioni `if/else`.
 
 # --hints--
 
-`isLess(10,15)` dovrebbe restituire `true`
+`isLess(10, 15)` dovrebbe restituire `true`
 
 ```js
 assert(isLess(10, 15) === true);
 ```
 
-`isLess(15,10)` dovrebbe restituire `false`
+`isLess(15, 10)` dovrebbe restituire `false`
 
 ```js
 assert(isLess(15, 10) === false);
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md
index cb0671f1e66..155d38ab423 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md
@@ -78,7 +78,7 @@ assert(code.match(/break/g).length > 2);
 
 ```js
 function caseInSwitch(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
 
@@ -94,7 +94,7 @@ caseInSwitch(1);
 
 ```js
 function caseInSwitch(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case 1:
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md
index e5815c13d4f..1e73a853748 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md
@@ -81,13 +81,13 @@ var hasNumber = false;
 ## --seed-contents--
 
 ```js
-var myList = [];
+const myList = [];
 ```
 
 # --solutions--
 
 ```js
-var myList = [
+const myList = [
   ["Candy", 10],
   ["Potatoes", 12],
   ["Eggs", 12],
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md
index 0d18c887b48..1547a7b8a41 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md
@@ -93,12 +93,10 @@ function nextInLine(arr, item) {
 
   return item;
   // Only change code above this line
-
-
 }
 
 // Setup
-var testArr = [1,2,3,4,5];
+const testArr = [1, 2, 3, 4, 5];
 
 // Display code
 console.log("Before: " + JSON.stringify(testArr));
@@ -109,7 +107,7 @@ console.log("After: " + JSON.stringify(testArr));
 # --solutions--
 
 ```js
-var testArr = [ 1,2,3,4,5];
+const testArr = [1, 2, 3, 4, 5];
 
 function nextInLine(arr, item) {
     arr.push(item);
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md
index d280f77f5b9..99e986b2a9d 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md
@@ -14,7 +14,7 @@ Con le variabili `array` di JavaScript, possiamo memorizzare diversi dati in un
 La dichiarazione di un array inizia con una parentesi quadra di apertura, e termina con una parentesi quadra di chiusura, con gli elementi separati da virgole, in questo modo:
 
 ```js
-var sandwich = ["peanut butter", "jelly", "bread"]
+const sandwich = ["peanut butter", "jelly", "bread"];
 ```
 
 # --instructions--
@@ -53,11 +53,11 @@ assert(typeof myArray[1] !== 'undefined' && typeof myArray[1] == 'number');
 
 ```js
 // Only change code below this line
-var myArray = [];
+const myArray = [];
 ```
 
 # --solutions--
 
 ```js
-var myArray = ["The Answer", 42];
+const myArray = ["The Answer", 42];
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md
index 767509bb366..627d6b8ff6b 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md
@@ -16,7 +16,7 @@ JavaScript utilizza il simbolo `-` per la sottrazione.
 **Esempio**
 
 ```js
-myVar = 12 - 6;
+const myVar = 12 - 6;
 ```
 
 `myVar` avrà il valore `6`.
@@ -49,11 +49,11 @@ assert(/difference=45-33;?/.test(__helpers.removeWhiteSpace(code)));
 ## --seed-contents--
 
 ```js
-var difference = 45 - 0;
+const difference = 45 - 0;
 ```
 
 # --solutions--
 
 ```js
-var difference = 45 - 33;
+const difference = 45 - 33;
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md
index a7ac8140578..01345fc3967 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md
@@ -13,10 +13,11 @@ A volte è utile verificare se la proprietà di un dato oggetto esiste o meno. P
 **Esempio**
 
 ```js
-var myObj = {
+const myObj = {
   top: "hat",
   bottom: "pants"
 };
+
 myObj.hasOwnProperty("top");
 myObj.hasOwnProperty("middle");
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md
index 779c4661dfd..0f3a4e8bb7e 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md
@@ -14,14 +14,14 @@ In JavaScript, le stringhe (`String`) sono <dfn>immutabili</dfn>, il che signifi
 Ad esempio, il codice seguente:
 
 ```js
-var myStr = "Bob";
+let myStr = "Bob";
 myStr[0] = "J";
 ```
 
 non può modificare il valore di `myStr` in `Job`, poiché il contenuto di `myStr` non può essere modificato. Tieni presente che questo *non* significa che `myStr` non può essere modificato, ma solo che i singoli caratteri di una <dfn>stringa letterale</dfn> non possono essere cambiati. L'unico modo per modificare `myStr` è di assegnargli una nuova stringa, in questo modo:
 
 ```js
-var myStr = "Bob";
+let myStr = "Bob";
 myStr = "Job";
 ```
 
@@ -55,7 +55,7 @@ assert(/myStr = "Jello World"/.test(code));
 
 ```js
 // Setup
-var myStr = "Jello World";
+let myStr = "Jello World";
 
 // Only change code below this line
 myStr[0] = "H"; // Change this line
@@ -65,6 +65,6 @@ myStr[0] = "H"; // Change this line
 # --solutions--
 
 ```js
-var myStr = "Jello World";
+let myStr = "Jello World";
 myStr = "Hello World";
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md
index 15d85f5f608..5d3c5e13fcb 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md
@@ -43,7 +43,6 @@ welcomeToBooleans();
 
 ```js
 function welcomeToBooleans() {
-
   // Only change code below this line
 
   return false; // Change this line
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md
index ec452a1a41a..c6229632088 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md
@@ -14,10 +14,12 @@ Una funzione può includere l'istruzione `return` ma questa non deve essere nece
 **Esempio**
 
 ```js
-var sum = 0;
+let sum = 0;
+
 function addSum(num) {
   sum = sum + num;
 }
+
 addSum(3);
 ```
 
@@ -61,7 +63,7 @@ assert(
 
 ```js
 // Setup
-var sum = 0;
+let sum = 0;
 
 function addThree() {
   sum = sum + 3;
@@ -79,7 +81,7 @@ addFive();
 # --solutions--
 
 ```js
-var sum = 0;
+let sum = 0;
 
 function addThree() {
   sum = sum + 3;
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md
index c3141f438f9..27d8a790c03 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md
@@ -14,7 +14,7 @@ Dopo aver creato un oggetto JavaScript, è possibile aggiornare le sue propriet
 Ad esempio, diamo un'occhiata a `ourDog`:
 
 ```js
-var ourDog = {
+const ourDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
@@ -54,7 +54,7 @@ assert(/"name": "Coder"/.test(code));
 
 ```js
 // Setup
-var myDog = {
+const myDog = {
   "name": "Coder",
   "legs": 4,
   "tails": 1,
@@ -62,12 +62,13 @@ var myDog = {
 };
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Coder",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-first-character-in-a-string.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-first-character-in-a-string.md
index 7b22d3e89f4..a4f84e0268f 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-first-character-in-a-string.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-first-character-in-a-string.md
@@ -13,13 +13,13 @@ dashedName: use-bracket-notation-to-find-the-first-character-in-a-string
 
 La maggior parte dei moderni linguaggi di programmazione, come JavaScript, non inizia a contare da 1 come gli esseri umani. Loro iniziano dallo 0. Questo è indicato come indicizzazione <dfn>Zero-based</dfn>.
 
-Ad esempio, il carattere all'indice 0 nella parola `Charles` è `C`. Quindi, se `var firstName = "Charles"`, è possibile ottenere il valore della prima lettera della stringa utilizzando `firstName[0]`.
+Ad esempio, il carattere all'indice 0 nella parola `Charles` è `C`. Quindi, se `const firstName = "Charles"`, è possibile ottenere il valore della prima lettera della stringa utilizzando `firstName[0]`.
 
 Esempio:
 
 ```js
-var firstName = "Charles";
-var firstLetter = firstName[0];
+const firstName = "Charles";
+const firstLetter = firstName[0];
 ```
 
 `firstLetter` dovrebbe avere un valore stringa `C`.
@@ -56,8 +56,8 @@ assert(code.match(/firstLetterOfLastName\s*?=\s*?lastName\[.*?\]/));
 
 ```js
 // Setup
-var firstLetterOfLastName = "";
-var lastName = "Lovelace";
+let firstLetterOfLastName = "";
+const lastName = "Lovelace";
 
 // Only change code below this line
 firstLetterOfLastName = lastName; // Change this line
@@ -66,8 +66,8 @@ firstLetterOfLastName = lastName; // Change this line
 # --solutions--
 
 ```js
-var firstLetterOfLastName = "";
-var lastName = "Lovelace";
+let firstLetterOfLastName = "";
+const lastName = "Lovelace";
 
 // Only change code below this line
 firstLetterOfLastName = lastName[0];
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-last-character-in-a-string.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-last-character-in-a-string.md
index 728b070b502..e19e3fe9fe3 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-last-character-in-a-string.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-last-character-in-a-string.md
@@ -11,13 +11,13 @@ dashedName: use-bracket-notation-to-find-the-last-character-in-a-string
 
 Al fine di ottenere l'ultima lettera di una stringa, è possibile sottrarre uno dalla lunghezza della stringa.
 
-Per esempio, se `var firstName = "Ada"`, puoi ottenere il valore dell'ultima lettera della stringa usando `firstName[firstName.length - 1]`.
+Per esempio, se `const firstName = "Ada"`, puoi ottenere il valore dell'ultima lettera della stringa usando `firstName[firstName.length - 1]`.
 
 Esempio:
 
 ```js
-var firstName = "Ada";
-var lastLetter = firstName[firstName.length - 1];
+const firstName = "Ada";
+const lastLetter = firstName[firstName.length - 1];
 ```
 
 `lastLetter` dovrebbe avere un valore stringa `a`.
@@ -54,15 +54,15 @@ assert(code.match(/\.length/g).length > 0);
 
 ```js
 // Setup
-var lastName = "Lovelace";
+const lastName = "Lovelace";
 
 // Only change code below this line
-var lastLetterOfLastName = lastName; // Change this line
+const lastLetterOfLastName = lastName; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var lastName = "Lovelace";
-var lastLetterOfLastName = lastName[lastName.length - 1];
+const lastName = "Lovelace";
+const lastLetterOfLastName = lastName[lastName.length - 1];
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md
index 32b4010e765..0e89b3f80f6 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md
@@ -16,8 +16,8 @@ Ricorda che i computer iniziano a contare da `0`, quindi il primo carattere è i
 Esempio:
 
 ```js
-var firstName = "Ada";
-var secondLetterOfFirstName = firstName[1];
+const firstName = "Ada";
+const secondLetterOfFirstName = firstName[1];
 ```
 
 `secondLetterOfFirstName` dovrebbe acere un valore stringa `d`.
@@ -54,15 +54,15 @@ assert(code.match(/thirdLetterOfLastName\s*?=\s*?lastName\[.*?\]/));
 
 ```js
 // Setup
-var lastName = "Lovelace";
+const lastName = "Lovelace";
 
 // Only change code below this line
-var thirdLetterOfLastName = lastName; // Change this line
+const thirdLetterOfLastName = lastName; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var lastName = "Lovelace";
-var thirdLetterOfLastName = lastName[2];
+const lastName = "Lovelace";
+const thirdLetterOfLastName = lastName[2];
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-to-last-character-in-a-string.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-to-last-character-in-a-string.md
index f29cf5783da..9e288b6f467 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-to-last-character-in-a-string.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-to-last-character-in-a-string.md
@@ -11,13 +11,13 @@ dashedName: use-bracket-notation-to-find-the-nth-to-last-character-in-a-string
 
 È possibile utilizzare lo stesso principio che abbiamo appena usato per recuperare l'ultimo carattere in una stringa per recuperare il carattere n-ultimo dalla fine.
 
-Ad esempio, puoi ottenere il valore della terzultima lettera della stringa `var firstName = "Augusta"` usando `firstName[firstName. lunghezza - 3]`
+Ad esempio, puoi ottenere il valore della terzultima lettera della stringa `const firstName = "Augusta"` usando `firstName[firstName.length - 3]`
 
 Esempio:
 
 ```js
-var firstName = "Augusta";
-var thirdToLastLetter = firstName[firstName.length - 3];
+const firstName = "Augusta";
+const thirdToLastLetter = firstName[firstName.length - 3];
 ```
 
 `thirdToLastLetter` dovrebbe avere un valore stringa `s`.
@@ -54,15 +54,15 @@ assert(code.match(/\.length/g).length > 0);
 
 ```js
 // Setup
-var lastName = "Lovelace";
+const lastName = "Lovelace";
 
 // Only change code below this line
-var secondToLastLetterOfLastName = lastName; // Change this line
+const secondToLastLetterOfLastName = lastName; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var lastName = "Lovelace";
-var secondToLastLetterOfLastName = lastName[lastName.length - 2];
+const lastName = "Lovelace";
+const secondToLastLetterOfLastName = lastName[lastName.length - 2];
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-conditional-logic-with-if-statements.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-conditional-logic-with-if-statements.md
index d563f229c83..a0712627a32 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-conditional-logic-with-if-statements.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-conditional-logic-with-if-statements.md
@@ -9,7 +9,7 @@ dashedName: use-conditional-logic-with-if-statements
 
 # --description--
 
-Le istruzioni `If` sono usate nel codice per prendere decisioni. La parola chiave `if` dice a JavaScript di eseguire il codice nelle parentesi graffe in determinate condizioni, definite nelle parentesi tonde. Queste condizioni sono note come condizioni `Boolean` e possono essere solo `true` o `false`.
+Le istruzioni `if` sono usate nel codice per prendere decisioni. La parola chiave `if` dice a JavaScript di eseguire il codice nelle parentesi graffe in determinate condizioni, definite nelle parentesi tonde. Queste condizioni sono note come condizioni `Boolean` e possono essere solo `true` o `false`.
 
 Quando la condizione valuta un `true`, il programma esegue la dichiarazione all'interno delle parentesi graffe. Quando la condizione booleana valuta un `false`, la dichiarazione all'interno delle parentesi graffe non sarà eseguita.
 
@@ -22,10 +22,11 @@ Quando la condizione valuta un `true`, il programma esegue la dichiarazione all'
 ```js
 function test (myCondition) {
   if (myCondition) {
-     return "It was true";
+    return "It was true";
   }
   return "It was false";
 }
+
 test(true);
 test(false);
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md
index 3f3574500e3..11cfe957417 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md
@@ -73,7 +73,7 @@ function rangeOfNumbers(startNum, endNum) {
   if (endNum - startNum === 0) {
     return [startNum];
   } else {
-    var numbers = rangeOfNumbers(startNum, endNum - 1);
+    const numbers = rangeOfNumbers(startNum, endNum - 1);
     numbers.push(endNum);
     return numbers;
   }
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md
index a13766d6846..a4001a6006b 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md
@@ -20,7 +20,7 @@ parseInt(string, radix);
 Ecco un esempio:
 
 ```js
-var a = parseInt("11", 2);
+const a = parseInt("11", 2);
 ```
 
 La variabile radix dice che `11` è nel sistema binario, o in base 2. Questo esempio converte la stringa `11` in un intero `3`.
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md
index ded630df7a2..3d11acc5080 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md
@@ -12,7 +12,7 @@ dashedName: use-the-parseint-function
 La funzione `parseInt()` analizza una stringa e restituisce un numero intero. Ecco un esempio:
 
 ```js
-var a = parseInt("007");
+const a = parseInt("007");
 ```
 
 La funzione di cui sopra converte la stringa `007` nell'intero `7`. Se il primo carattere della stringa non può essere convertito in un numero, restituisce `NaN`.
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md
index f238d440ba9..bc280c8f390 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md
@@ -14,7 +14,7 @@ Gli oggetti possono essere pensati come una memorizzazione di coppie chiave / va
 Ecco l'esempio di una semplice ricerca in un alfabeto inverso:
 
 ```js
-var alpha = {
+const alpha = {
   1:"Z",
   2:"Y",
   3:"X",
@@ -24,10 +24,11 @@ var alpha = {
   25:"B",
   26:"A"
 };
+
 alpha[2];
 alpha[24];
 
-var value = 2;
+const value = 2;
 alpha[value];
 ```
 
@@ -102,7 +103,7 @@ assert(
 ```js
 // Setup
 function phoneticLookup(val) {
-  var result = "";
+  let result = "";
 
   // Only change code below this line
   switch(val) {
@@ -136,9 +137,9 @@ phoneticLookup("charlie");
 
 ```js
 function phoneticLookup(val) {
-  var result = "";
+  let result = "";
 
-  var lookup = {
+  const lookup = {
     alpha: "Adams",
     bravo: "Boston",
     charlie: "Chicago",
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md
index b358f58679b..96e39636aa6 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md
@@ -16,7 +16,7 @@ In un gioco "Mad Libs" ti vengono fornite frasi con alcune parole mancanti, come
 Considera questa frase: It was really **\_\_\_\_**, and we **\_\_\_\_** ourselves **\_\_\_\_**. Questa frase ha tre parti mancanti - un aggettivo, un verbo e un avverbio, e possiamo aggiungere parole di nostra scelta per completarla. Possiamo quindi assegnare la frase completata a una variabile come segue:
 
 ```js
-var sentence = "It was really " + "hot" + ", and we " + "laughed" + " ourselves " + "silly" + ".";
+const sentence = "It was really " + "hot" + ", and we " + "laughed" + " ourselves " + "silly" + ".";
 ```
 
 # --instructions--
@@ -84,24 +84,24 @@ const removeAssignments = str => str
 ## --seed-contents--
 
 ```js
-var myNoun = "dog";
-var myAdjective = "big";
-var myVerb = "ran";
-var myAdverb = "quickly";
+const myNoun = "dog";
+const myAdjective = "big";
+const myVerb = "ran";
+const myAdverb = "quickly";
 
 // Only change code below this line
-var wordBlanks = ""; // Change this line
+const wordBlanks = ""; // Change this line
 // Only change code above this line
 ```
 
 # --solutions--
 
 ```js
-var myNoun = "dog";
-var myAdjective = "big";
-var myVerb = "ran";
-var myAdverb = "quickly";
+const myNoun = "dog";
+const myAdjective = "big";
+const myVerb = "ran";
+const myAdverb = "quickly";
 
-var wordBlanks = "Once there was a " + myNoun + " which was very " + myAdjective + ". ";
+let wordBlanks = "Once there was a " + myNoun + " which was very " + myAdjective + ". ";
 wordBlanks += "It " + myVerb + " " + myAdverb + " around the yard.";
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/es6/compare-scopes-of-the-var-and-let-keywords.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/es6/compare-scopes-of-the-var-and-let-keywords.md
index 78b0ae1d53e..8f8ef090d24 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/es6/compare-scopes-of-the-var-and-let-keywords.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/es6/compare-scopes-of-the-var-and-let-keywords.md
@@ -8,11 +8,13 @@ dashedName: compare-scopes-of-the-var-and-let-keywords
 
 # --description--
 
+Se non hai familiarità con `let`, guarda [questa sfida](/italian/learn/javascript-algorithms-and-data-structures/basic-javascript/explore-differences-between-the-var-and-let-keywords).
+
 Quando si dichiara una variabile con la parola chiave `var`, essa viene dichiarata globalmente, o localmente se dichiarata all'interno di una funzione.
 
 La parola chiave `let` si comporta allo stesso modo, ma con alcune funzioni extra. Quando si dichiara una variabile con la parola chiave `let` all'interno di un blocco, di una dichiarazione o di un'espressione, il suo ambito di applicazione è limitato a tale blocco, dichiarazione o espressione.
 
-Ad esempio:
+Per esempio:
 
 ```js
 var numArray = [];
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/es6/mutate-an-array-declared-with-const.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/es6/mutate-an-array-declared-with-const.md
index 90afce5d3b2..584d9b959e6 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/es6/mutate-an-array-declared-with-const.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/es6/mutate-an-array-declared-with-const.md
@@ -8,6 +8,8 @@ dashedName: mutate-an-array-declared-with-const
 
 # --description--
 
+Se non hai familiarità con `const`, guarda [questa sfida](/italian/learn/javascript-algorithms-and-data-structures/basic-javascript/declare-a-read-only-variable-with-the-const-keyword).
+
 La dichiarazione `const` ha molti casi di utilizzo nel JavaScript moderno.
 
 Alcuni sviluppatori preferiscono assegnare tutte le loro variabili usando `const` come impostazione predefinita, a meno che non sappiano che dovranno riassegnare il valore. Solo in quel caso usano `let`.
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md
index ec106d4bad9..7de60422feb 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md
@@ -13,7 +13,7 @@ La programmazione funzionale riguarda la creazione e l'utilizzo di funzioni non
 L'ultima sfida ha introdotto il metodo `concat` come modo per combinare degli array in uno nuovo senza mutare gli array originali. Confronta `concat` con il metodo `push`. `push` aggiunge un elemento alla fine dello stesso array sul quale viene richiamato, mutando quello stesso array. Ecco un esempio:
 
 ```js
-var arr = [1, 2, 3];
+const arr = [1, 2, 3];
 arr.push([4, 5, 6]);
 ```
 
@@ -71,8 +71,9 @@ function nonMutatingPush(original, newItem) {
 
   // Only change code above this line
 }
-var first = [1, 2, 3];
-var second = [4, 5];
+
+const first = [1, 2, 3];
+const second = [4, 5];
 nonMutatingPush(first, second);
 ```
 
@@ -82,7 +83,6 @@ nonMutatingPush(first, second);
 function nonMutatingPush(original, newItem) {
   return original.concat(newItem);
 }
-var first = [1, 2, 3];
-var second = [4, 5];
-nonMutatingPush(first, second);
+const first = [1, 2, 3];
+const second = [4, 5];
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md
index b17658cb35d..0be730b16ef 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md
@@ -77,7 +77,6 @@ function urlSlug(title) {
 # --solutions--
 
 ```js
-// Only change code below this line
 function urlSlug(title) {
   return title.trim().split(/\s+/).join("-").toLowerCase();
 }
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md
index 4c05d5ff648..d3aabcc8b07 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md
@@ -57,9 +57,9 @@ La tua funzione `incrementer` dovrebbe restituire un valore basato sul valore de
 
 ```js
 // The global variable
-var fixedValue = 4;
+let fixedValue = 4;
 
-function incrementer () {
+function incrementer() {
   // Only change code below this line
 
 
@@ -70,7 +70,7 @@ function incrementer () {
 # --solutions--
 
 ```js
-var fixedValue = 4
+let fixedValue = 4
 
 function incrementer() {
   return fixedValue + 1
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md
index 8cbb8ed9d93..276483c0d6e 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md
@@ -13,8 +13,8 @@ Il metodo `join` viene utilizzato per unire gli elementi di un array per creare
 Ecco un esempio:
 
 ```js
-var arr = ["Hello", "World"];
-var str = arr.join(" ");
+const arr = ["Hello", "World"];
+const str = arr.join(" ");
 ```
 
 `str` conterrà la stringa `Hello World`.
@@ -76,6 +76,7 @@ function sentensify(str) {
 
   // Only change code above this line
 }
+
 sentensify("May-the-force-be-with-you");
 ```
 
@@ -83,8 +84,6 @@ sentensify("May-the-force-be-with-you");
 
 ```js
 function sentensify(str) {
-  // Only change code below this line
   return str.split(/\W/).join(' ');
-  // Only change code above this line
 }
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md
index 2e670d61e9a..9080414f5bc 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md
@@ -60,8 +60,9 @@ function nonMutatingConcat(original, attach) {
 
   // Only change code above this line
 }
-var first = [1, 2, 3];
-var second = [4, 5];
+
+const first = [1, 2, 3];
+const second = [4, 5];
 nonMutatingConcat(first, second);
 ```
 
@@ -69,11 +70,8 @@ nonMutatingConcat(first, second);
 
 ```js
 function nonMutatingConcat(original, attach) {
-  // Only change code below this line
   return original.concat(attach);
-  // Only change code above this line
 }
-var first = [1, 2, 3];
-var second = [4, 5];
-nonMutatingConcat(first, second);
+const first = [1, 2, 3];
+const second = [4, 5];
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md
index 7481fe5ad4b..f86c26fd5a9 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md
@@ -38,17 +38,17 @@ assert(!code.match(/\.?[\s\S]*?map/g));
 
 ```js
 // The global variable
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myMap = function(callback) {
-  var newArray = [];
+  const newArray = [];
   // Only change code below this line
 
   // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myMap(function(item) {
+const new_s = s.myMap(function(item) {
   return item * 2;
 });
 ```
@@ -56,20 +56,17 @@ var new_s = s.myMap(function(item) {
 # --solutions--
 
 ```js
-// the global Array
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myMap = function(callback) {
-  var newArray = [];
-  // Only change code below this line
-  for (var elem of this) {
+  const newArray = [];
+  for (const elem of this) {
     newArray.push(callback(elem));
   }
-  // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myMap(function(item) {
+const new_s = s.myMap(function(item) {
   return item * 2;
 });
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md
index 0ac91d4557f..be2cd8f1b80 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md
@@ -34,16 +34,16 @@ assert(!code.match(/\.?[\s\S]*?filter/g));
 
 ```js
 // The global variable
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myFilter = function(callback) {
   // Only change code below this line
-  var newArray = [];
+  const newArray = [];
   // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myFilter(function(item) {
+const new_s = s.myFilter(function(item) {
   return item % 2 === 1;
 });
 ```
@@ -51,20 +51,17 @@ var new_s = s.myFilter(function(item) {
 # --solutions--
 
 ```js
-// the global Array
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myFilter = function(callback) {
-  var newArray = [];
-  // Only change code below this line
+  const newArray = [];
   for (let i = 0; i < this.length; i++) {
     if (callback(this[i])) newArray.push(this[i]);
   }
-  // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myFilter(function(item) {
+const new_s = s.myFilter(function(item) {
   return item % 2 === 1;
 });
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md
index 08b0f550945..a16389a1195 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md
@@ -35,7 +35,7 @@ curried(1)(2)
 Questo sarà utile nel tuo programma se non sarai in grado di fornire tutti gli argomenti ad una funzione in una sola volta. Potrai salvare ogni chiamata di funzione in una variabile, che manterrà il riferimento alla funzione restituita, che prenderà l'argomento successivo quando sarà disponibile. Ecco un esempio usando la funzione curried dell'esempio visto sopra:
 
 ```js
-var funcForY = curried(1);
+const funcForY = curried(1);
 console.log(funcForY(2)); // 3
 ```
 
@@ -45,7 +45,8 @@ Allo stesso modo, <dfn>l'applicazione parziale</dfn> può essere descritta come
 function impartial(x, y, z) {
   return x + y + z;
 }
-var partialFn = impartial.bind(this, 1, 2);
+
+const partialFn = impartial.bind(this, 1, 2);
 partialFn(10); // 13
 ```
 
@@ -90,6 +91,7 @@ function add(x) {
 
   // Only change code above this line
 }
+
 add(10)(20)(30);
 ```
 
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md
index abbc1b478f7..593d57dbe94 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md
@@ -53,10 +53,10 @@ assert(__newValue === 5);
 
 ```js
 // The global variable
-var fixedValue = 4;
+let fixedValue = 4;
 
 // Only change code below this line
-function incrementer () {
+function incrementer() {
 
 
   // Only change code above this line
@@ -66,15 +66,9 @@ function incrementer () {
 # --solutions--
 
 ```js
-// The global variable
-var fixedValue = 4;
+let fixedValue = 4;
 
-// Only change code below this line
-function incrementer (fixedValue) {
+function incrementer(fixedValue) {
   return fixedValue + 1;
-
-  // Only change code above this line
 }
-
-
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/refactor-global-variables-out-of-functions.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/refactor-global-variables-out-of-functions.md
index ac1d10eac03..0f1f353bd31 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/refactor-global-variables-out-of-functions.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/refactor-global-variables-out-of-functions.md
@@ -10,7 +10,7 @@ dashedName: refactor-global-variables-out-of-functions
 
 Finora abbiamo visto due principi distinti per la programmazione funzionale:
 
-1) Non modificare una variabile o un oggetto - se necessario creare nuove variabili e oggetti e restituirli da una funzione. Suggerimento: usando qualcosa come `var newArr = arrVar`, dove `arrVar` è un array, creerai semplicemente un riferimento alla variabile esistente e non una copia. Quindi cambiando un valore in `newArr` cambierà anche il valore in `arrVar`.
+1) Non modificare una variabile o un oggetto - se necessario creare nuove variabili e oggetti e restituirli da una funzione. Suggerimento: usando qualcosa come `const newArr = arrVar`, dove `arrVar` è un array, creerai semplicemente un riferimento alla variabile esistente e non una copia. Quindi cambiando un valore in `newArr` cambierà anche il valore in `arrVar`.
 
 2) Dichiarare i parametri della funzione - qualsiasi calcolo all'interno di una funzione deve dipendere solo dagli argomenti passati alla funzione, e non da qualsiasi oggetto o variabile globale.
 
@@ -86,7 +86,7 @@ assert(
 
 ```js
 // The global variable
-var bookList = ["The Hound of the Baskervilles", "On The Electrodynamics of Moving Bodies", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae"];
+const bookList = ["The Hound of the Baskervilles", "On The Electrodynamics of Moving Bodies", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae"];
 
 // Change code below this line
 function add (bookName) {
@@ -99,7 +99,7 @@ function add (bookName) {
 
 // Change code below this line
 function remove (bookName) {
-  var book_index = bookList.indexOf(bookName);
+  const book_index = bookList.indexOf(bookName);
   if (book_index >= 0) {
 
     bookList.splice(book_index, 1);
@@ -109,9 +109,9 @@ function remove (bookName) {
     }
 }
 
-var newBookList = add(bookList, 'A Brief History of Time');
-var newerBookList = remove(bookList, 'On The Electrodynamics of Moving Bodies');
-var newestBookList = remove(add(bookList, 'A Brief History of Time'), 'On The Electrodynamics of Moving Bodies');
+const newBookList = add(bookList, 'A Brief History of Time');
+const newerBookList = remove(bookList, 'On The Electrodynamics of Moving Bodies');
+const newestBookList = remove(add(bookList, 'A Brief History of Time'), 'On The Electrodynamics of Moving Bodies');
 
 console.log(bookList);
 ```
@@ -120,13 +120,13 @@ console.log(bookList);
 
 ```js
 // The global variable
-var bookList = ["The Hound of the Baskervilles", "On The Electrodynamics of Moving Bodies", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae"];
+const bookList = ["The Hound of the Baskervilles", "On The Electrodynamics of Moving Bodies", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae"];
 
-function add (bookList, bookName) {
+function add(bookList, bookName) {
   return [...bookList, bookName];
 }
 
-function remove (bookList, bookName) {
+function remove(bookList, bookName) {
   const bookListCopy = [...bookList];
   const bookNameIndex = bookList.indexOf(bookName);
   if (bookNameIndex >= 0) {
@@ -135,7 +135,7 @@ function remove (bookList, bookName) {
   return bookListCopy;
 }
 
-var newBookList = add(bookList, 'A Brief History of Time');
-var newerBookList = remove(bookList, 'On The Electrodynamics of Moving Bodies');
-var newestBookList = remove(add(bookList, 'A Brief History of Time'), 'On The Electrodynamics of Moving Bodies');
+const newBookList = add(bookList, 'A Brief History of Time');
+const newerBookList = remove(bookList, 'On The Electrodynamics of Moving Bodies');
+const newestBookList = remove(add(bookList, 'A Brief History of Time'), 'On The Electrodynamics of Moving Bodies');
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md
index 98ba6cd7ea0..42204ce06e4 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md
@@ -11,7 +11,7 @@ dashedName: remove-elements-from-an-array-using-slice-instead-of-splice
 Un'operazione che si fa comunemente lavorando con gli array è quella di rimuovere degli elemento mantenendo il resto dell'array. A questo scopo JavaScript offre il metodo `splice`, che richiede degli argomenti per la posizione (indice) di dove iniziare a rimuovere gli elementi, e per il numero di elementi da rimuovere. Se il secondo argomento non è fornito, il comportamento predefinito è quello di rimuovere gli elementi fino alla fine. Tuttavia, il metodo `splice` muta l'array originale su cui viene chiamato. Ecco un esempio:
 
 ```js
-var cities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
+const cities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
 cities.splice(3, 1);
 ```
 
@@ -69,7 +69,8 @@ function nonMutatingSplice(cities) {
 
   // Only change code above this line
 }
-var inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
+
+const inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
 nonMutatingSplice(inputCities);
 ```
 
@@ -77,10 +78,7 @@ nonMutatingSplice(inputCities);
 
 ```js
 function nonMutatingSplice(cities) {
-  // Only change code below this line
   return cities.slice(0,3);
-  // Only change code above this line
 }
-var inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
-nonMutatingSplice(inputCities);
+const inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md
index c68e75beabd..41dd0b004cf 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md
@@ -68,24 +68,23 @@ assert(JSON.stringify(nonMutatingSort([140000, 104, 99])) ===
 ## --seed-contents--
 
 ```js
-var globalArray = [5, 6, 3, 2, 9];
+const globalArray = [5, 6, 3, 2, 9];
+
 function nonMutatingSort(arr) {
   // Only change code below this line
 
 
   // Only change code above this line
 }
+
 nonMutatingSort(globalArray);
 ```
 
 # --solutions--
 
 ```js
-var globalArray = [5, 6, 3, 2, 9];
+const globalArray = [5, 6, 3, 2, 9];
 function nonMutatingSort(arr) {
-  // Only change code below this line
   return [].concat(arr).sort((a,b) => a-b);
-  // Only change code above this line
 }
-nonMutatingSort(globalArray);
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md
index 100adb00acd..7334fcec523 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md
@@ -13,8 +13,8 @@ Il metodo `slice` restituisce una copia di alcuni elementi di un array. Può pre
 Ecco un esempio:
 
 ```js
-var arr = ["Cat", "Dog", "Tiger", "Zebra"];
-var newArray = arr.slice(1, 3);
+const arr = ["Cat", "Dog", "Tiger", "Zebra"];
+const newArray = arr.slice(1, 3);
 ```
 
 `newArray` avrà il valore `["Dog", "Tiger"]`.
@@ -78,7 +78,8 @@ function sliceArray(anim, beginSlice, endSlice) {
 
   // Only change code above this line
 }
-var inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
+
+const inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
 sliceArray(inputAnim, 1, 3);
 ```
 
@@ -86,10 +87,7 @@ sliceArray(inputAnim, 1, 3);
 
 ```js
 function sliceArray(anim, beginSlice, endSlice) {
-  // Only change code below this line
-  return anim.slice(beginSlice, endSlice)
-  // Only change code above this line
+  return anim.slice(beginSlice, endSlice);
 }
-var inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
-sliceArray(inputAnim, 1, 3);
+const inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md
index ffda7234fe4..5f20c74f670 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md
@@ -18,6 +18,7 @@ function ascendingOrder(arr) {
     return a - b;
   });
 }
+
 ascendingOrder([1, 5, 2, 3, 4]);
 ```
 
@@ -29,6 +30,7 @@ function reverseAlpha(arr) {
     return a === b ? 0 : a < b ? 1 : -1;
   });
 }
+
 reverseAlpha(['l', 'h', 'z', 'b', 's']);
 ```
 
@@ -86,6 +88,7 @@ function alphabeticalOrder(arr) {
   return arr
   // Only change code above this line
 }
+
 alphabeticalOrder(["a", "d", "c", "a", "z", "g"]);
 ```
 
@@ -93,9 +96,6 @@ alphabeticalOrder(["a", "d", "c", "a", "z", "g"]);
 
 ```js
 function alphabeticalOrder(arr) {
-  // Only change code below this line
   return arr.sort();
-  // Only change code above this line
 }
-alphabeticalOrder(["a", "d", "c", "a", "z", "g"]);
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md
index 1cdcb7b47af..4a9e267ca4e 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md
@@ -13,11 +13,11 @@ Il metodo `split` divide una stringa in un array di stringhe. Esso richiede un a
 Ecco un esempio che divide una stringa in base agli spazi, poi un altro in base alle cifre facendo uso di un'espressione regolare:
 
 ```js
-var str = "Hello World";
-var bySpace = str.split(" ");
+const str = "Hello World";
+const bySpace = str.split(" ");
 
-var otherString = "How9are7you2today";
-var byDigits = otherString.split(/\d/);
+const otherString = "How9are7you2today";
+const byDigits = otherString.split(/\d/);
 ```
 
 `bySpace` avrà il valore `["Hello", "World"]` e `byDigits` avrà il valore `["How", "are", "you", "today"]`.
@@ -74,6 +74,7 @@ function splitify(str) {
 
   // Only change code above this line
 }
+
 splitify("Hello World,I-am code");
 ```
 
@@ -81,8 +82,6 @@ splitify("Hello World,I-am code");
 
 ```js
 function splitify(str) {
-  // Only change code below this line
   return str.split(/\W/);
-  // Only change code above this line
 }
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md
index 05be76d717f..ce4c54fcf2f 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md
@@ -59,29 +59,29 @@ assert.deepEqual(finalTabs.tabs, [
 
 ```js
 // tabs is an array of titles of each site open within the window
-var Window = function(tabs) {
+const Window = function(tabs) {
   this.tabs = tabs; // We keep a record of the array inside the object
 };
 
 // When you join two windows into one window
-Window.prototype.join = function (otherWindow) {
+Window.prototype.join = function(otherWindow) {
   this.tabs = this.tabs.concat(otherWindow.tabs);
   return this;
 };
 
 // When you open a new tab at the end
-Window.prototype.tabOpen = function (tab) {
+Window.prototype.tabOpen = function(tab) {
   this.tabs.push('new tab'); // Let's open a new tab for now
   return this;
 };
 
 // When you close a tab
-Window.prototype.tabClose = function (index) {
+Window.prototype.tabClose = function(index) {
 
   // Only change code below this line
 
-  var tabsBeforeIndex = this.tabs.splice(0, index); // Get the tabs before the tab
-  var tabsAfterIndex = this.tabs.splice(index + 1); // Get the tabs after the tab
+  const tabsBeforeIndex = this.tabs.splice(0, index); // Get the tabs before the tab
+  const tabsAfterIndex = this.tabs.splice(index + 1); // Get the tabs after the tab
 
   this.tabs = tabsBeforeIndex.concat(tabsAfterIndex); // Join them together
 
@@ -91,12 +91,12 @@ Window.prototype.tabClose = function (index) {
  };
 
 // Let's create three browser windows
-var workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']); // Your mailbox, drive, and other work sites
-var socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']); // Social sites
-var videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']); // Entertainment sites
+const workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']); // Your mailbox, drive, and other work sites
+const socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']); // Social sites
+const videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']); // Entertainment sites
 
 // Now perform the tab opening, closing, and other operations
-var finalTabs = socialWindow
+const finalTabs = socialWindow
   .tabOpen() // Open a new tab for cat memes
   .join(videoWindow.tabClose(2)) // Close third tab in video window, and join
   .join(workWindow.tabClose(1).tabOpen());
@@ -106,40 +106,34 @@ console.log(finalTabs.tabs);
 # --solutions--
 
 ```js
-// tabs is an array of titles of each site open within the window
-var Window = function(tabs) {
-  this.tabs = tabs; // We keep a record of the array inside the object
+const Window = function(tabs) {
+  this.tabs = tabs;
 };
 
-// When you join two windows into one window
-Window.prototype.join = function (otherWindow) {
+Window.prototype.join = function(otherWindow) {
   this.tabs = this.tabs.concat(otherWindow.tabs);
   return this;
 };
 
-// When you open a new tab at the end
-Window.prototype.tabOpen = function (tab) {
-  this.tabs.push('new tab'); // Let's open a new tab for now
+Window.prototype.tabOpen = function(tab) {
+  this.tabs.push('new tab');
   return this;
 };
 
-// When you close a tab
-Window.prototype.tabClose = function (index) {
-  var tabsBeforeIndex = this.tabs.slice(0, index); // Get the tabs before the tab
-  var tabsAfterIndex = this.tabs.slice(index + 1); // Get the tabs after the tab
+Window.prototype.tabClose = function(index) {
+  const tabsBeforeIndex = this.tabs.slice(0, index);
+  const tabsAfterIndex = this.tabs.slice(index + 1);
 
-  this.tabs = tabsBeforeIndex.concat(tabsAfterIndex); // Join them together
+  this.tabs = tabsBeforeIndex.concat(tabsAfterIndex);
   return this;
  };
 
-// Let's create three browser windows
-var workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']); // Your mailbox, drive, and other work sites
-var socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']); // Social sites
-var videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']); //  Entertainment sites
+const workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']);
+const socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']);
+const videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']);
 
-// Now perform the tab opening, closing, and other operations
-var finalTabs = socialWindow
-  .tabOpen() // Open a new tab for cat memes
-  .join(videoWindow.tabClose(2)) // Close third tab in video window, and join
+const finalTabs = socialWindow
+  .tabOpen()
+  .join(videoWindow.tabClose(2))
   .join(workWindow.tabClose(1).tabOpen());
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md
index a0aa580e98b..02cfc87dd59 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md
@@ -13,7 +13,8 @@ Il metodo `every` funziona con gli array per controllare se *ogni* elemento supe
 Ad esempio, il seguente codice controllerà se ogni elemento nell'array `numbers` è inferiore a 10:
 
 ```js
-var numbers = [1, 5, 8, 0, 10, 11];
+const numbers = [1, 5, 8, 0, 10, 11];
+
 numbers.every(function(currentValue) {
   return currentValue < 10;
 });
@@ -62,6 +63,7 @@ function checkPositive(arr) {
 
   // Only change code above this line
 }
+
 checkPositive([1, 2, 3, -4, 5]);
 ```
 
@@ -69,9 +71,6 @@ checkPositive([1, 2, 3, -4, 5]);
 
 ```js
 function checkPositive(arr) {
-  // Only change code below this line
   return arr.every(num => num > 0);
-  // Only change code above this line
 }
-checkPositive([1, 2, 3, -4, 5]);
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-filter-method-to-extract-data-from-an-array.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-filter-method-to-extract-data-from-an-array.md
index 1806ad107df..d07c29105c7 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-filter-method-to-extract-data-from-an-array.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-filter-method-to-extract-data-from-an-array.md
@@ -55,7 +55,7 @@ Il tuo codice non dovrebbe utilizzare un ciclo `for`.
 assert(!code.match(/for\s*?\([\s\S]*?\)/g));
 ```
 
-`filteredList` dovrebbe essere uguale a `[{"title": "Inception","rating": "8.8"},{"title": "Interstellar","rating": "8.6"},{"title": "The Dark Knight","rating": "9.0"},{"title": "Batman Begins","rating": "8.3"}]`.
+`filteredList` dovrebbe essere uguale a `[{"title": "Inception", "rating": "8.8"}, {"title": "Interstellar", "rating": "8.6"}, {"title": "The Dark Knight", "rating": "9.0"}, {"title": "Batman Begins", "rating": "8.3"}]`.
 
 ```js
 assert.deepEqual(filteredList, [
@@ -72,7 +72,7 @@ assert.deepEqual(filteredList, [
 
 ```js
 // The global variable
-var watchList = [
+const watchList = [
   {
     "Title": "Inception",
     "Year": "2010",
@@ -187,7 +187,7 @@ var watchList = [
 
 // Only change code below this line
 
-var filteredList;
+const filteredList = "";
 
 // Only change code above this line
 
@@ -197,8 +197,7 @@ console.log(filteredList);
 # --solutions--
 
 ```js
-// The global variable
-var watchList = [
+const watchList = [
   {
     "Title": "Inception",
     "Year": "2010",
@@ -311,7 +310,5 @@ var watchList = [
   }
 ];
 
-// Only change code below this line
-let filteredList = watchList.filter(e => e.imdbRating >= 8).map( ({Title: title, imdbRating: rating}) => ({title, rating}) );
-// Only change code above this line
+const filteredList = watchList.filter(e => e.imdbRating >= 8).map( ({Title: title, imdbRating: rating}) => ({title, rating}) );
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-map-method-to-extract-data-from-an-array.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-map-method-to-extract-data-from-an-array.md
index 4560004153e..5990cfeae4e 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-map-method-to-extract-data-from-an-array.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-map-method-to-extract-data-from-an-array.md
@@ -61,7 +61,7 @@ Il tuo codice dovrebbe utilizzare il metodo `map`.
 assert(code.match(/\.map/g));
 ```
 
-`ratings` dovrebbe essere uguale a `[{"title":"Inception","rating":"8.8"},{"title":"Interstellar","rating":"8.6"},{"title":"The Dark Knight","rating":"9.0"},{"title":"Batman Begins","rating":"8.3"},{"title":"Avatar","rating":"7.9"}]`.
+`ratings` dovrebbe essere uguale a `[{"title": "Inception", "rating": "8.8"}, {"title": "Interstellar", "rating": "8.6"}, {"title": "The Dark Knight", "rating": "9.0"},{"title": "Batman Begins", "rating": "8.3"}, {"title": "Avatar", "rating": "7.9"}]`.
 
 ```js
 assert.deepEqual(ratings, [
@@ -79,7 +79,7 @@ assert.deepEqual(ratings, [
 
 ```js
 // The global variable
-var watchList = [
+const watchList = [
   {
     "Title": "Inception",
     "Year": "2010",
@@ -194,9 +194,9 @@ var watchList = [
 
 // Only change code below this line
 
-var ratings = [];
-for(var i=0; i < watchList.length; i++){
-  ratings.push({title: watchList[i]["Title"],  rating: watchList[i]["imdbRating"]});
+const ratings = [];
+for (let i = 0; i < watchList.length; i++) {
+  ratings.push({title: watchList[i]["Title"], rating: watchList[i]["imdbRating"]});
 }
 
 // Only change code above this line
@@ -207,8 +207,7 @@ console.log(JSON.stringify(ratings));
 # --solutions--
 
 ```js
-// The global variable
-var watchList = [
+const watchList = [
   {
     "Title": "Inception",
     "Year": "2010",
@@ -321,7 +320,7 @@ var watchList = [
   }
 ];
 
-var ratings = watchList.map(function(movie) {
+const ratings = watchList.map(function(movie) {
   return {
     title: movie["Title"],
     rating: movie["imdbRating"]
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md
index b099d5bde6d..fefae672b96 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md
@@ -93,7 +93,7 @@ assert(getRating(watchList.filter((_, i) => i < 1 || i > 2)) === 8.55);
 
 ```js
 // The global variable
-var watchList = [
+const watchList = [
   {
     "Title": "Inception",
     "Year": "2010",
@@ -206,22 +206,22 @@ var watchList = [
   }
 ];
 
-function getRating(watchList){
+function getRating(watchList) {
   // Only change code below this line
-  var averageRating;
+  let averageRating;
 
 
   // Only change code above this line
   return averageRating;
 }
+
 console.log(getRating(watchList));
 ```
 
 # --solutions--
 
 ```js
-// The global variable
-var watchList = [
+const watchList = [
   {
     "Title": "Inception",
     "Year": "2010",
@@ -334,8 +334,8 @@ var watchList = [
   }
 ];
 
-function getRating(watchList){
-  var averageRating;
+function getRating(watchList) {
+  let averageRating;
   const rating = watchList
     .filter(obj => obj.Director === "Christopher Nolan")
     .map(obj => Number(obj.imdbRating));
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md
index 4463777602c..6e40098e444 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md
@@ -13,7 +13,8 @@ Il metodo `some` funziona con gli array per verificare se *un qualunque* element
 Ad esempio, il seguente codice controllerà se almeno un elemento nell'array `numbers` è inferiore a 10:
 
 ```js
-var numbers = [10, 50, 8, 220, 110, 11];
+const numbers = [10, 50, 8, 220, 110, 11];
+
 numbers.some(function(currentValue) {
   return currentValue < 10;
 });
@@ -62,6 +63,7 @@ function checkPositive(arr) {
 
   // Only change code above this line
 }
+
 checkPositive([1, 2, 3, -4, 5]);
 ```
 
@@ -69,9 +71,6 @@ checkPositive([1, 2, 3, -4, 5]);
 
 ```js
 function checkPositive(arr) {
-  // Only change code below this line
   return arr.some(elem => elem > 0);
-  // Only change code above this line
 }
-checkPositive([1, 2, 3, -4, 5]);
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md
index 5d6f36636e5..8c51c56de1f 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md
@@ -157,7 +157,7 @@ assert(diffArray([1, 'calf', 3, 'piglet'], [7, 'filly']).length === 6);
 
 ```js
 function diffArray(arr1, arr2) {
-  var newArr = [];
+  const newArr = [];
   return newArr;
 }
 
@@ -168,13 +168,12 @@ diffArray([1, 2, 3, 5], [1, 2, 3, 4, 5]);
 
 ```js
 function diffArray(arr1, arr2) {
-  var newArr = [];
-  var h1 = Object.create(null);
+  const newArr = [];
+  const h1 = Object.create(null);
   arr1.forEach(function(e) {
     h1[e] = e;
   });
-
-  var h2 = Object.create(null);
+  const h2 = Object.create(null);
   arr2.forEach(function(e) {
     h2[e] = e;
   });
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md
index 63db2d40aa8..29d39ca0092 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md
@@ -23,10 +23,19 @@ Esegui i test per vedere l'output atteso per ogni metodo. I metodi che prendono
 
 # --hints--
 
-`Object.keys(bob).length` dovrebbe restituire 6.
+Nessuna proprietà dovrebbe essere aggiunta. `Object.keys(bob).length` dovrebbe sempre restituire 6.
 
 ```js
-assert.deepEqual(Object.keys(bob).length, 6);
+assert.strictEqual(
+  Object.keys((function () {
+    let bob = new Person('Bob Ross');
+    bob.setFirstName('Haskell');
+    bob.setLastName('Curry');
+    bob.setFullName('John Smith');
+    return bob;
+  })()).length,
+  6
+ );
 ```
 
 `bob instanceof Person` dovrebbe restituire `true`.
@@ -139,7 +148,7 @@ if(bob){
 ## --seed-contents--
 
 ```js
-var Person = function(firstAndLast) {
+const Person = function(firstAndLast) {
   // Only change code below this line
   // Complete the method below and implement the others similarly
   this.getFullName = function() {
@@ -148,16 +157,16 @@ var Person = function(firstAndLast) {
   return firstAndLast;
 };
 
-var bob = new Person('Bob Ross');
+const bob = new Person('Bob Ross');
 bob.getFullName();
 ```
 
 # --solutions--
 
 ```js
-var Person = function(firstAndLast) {
+const Person = function(firstAndLast) {
 
-  var firstName, lastName;
+  let firstName, lastName;
 
   function updateName(str) {
     firstName = str.split(" ")[0];
@@ -192,6 +201,6 @@ var Person = function(firstAndLast) {
   };
 };
 
-var bob = new Person('Bob Ross');
+const bob = new Person('Bob Ross');
 bob.getFullName();
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md
index 001fc277e21..5aafa241b3a 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md
@@ -51,8 +51,8 @@ assert.deepEqual(
 
 ```js
 function orbitalPeriod(arr) {
-  var GM = 398600.4418;
-  var earthRadius = 6367.4447;
+  const GM = 398600.4418;
+  const earthRadius = 6367.4447;
   return arr;
 }
 
@@ -63,9 +63,9 @@ orbitalPeriod([{name : "sputnik", avgAlt : 35873.5553}]);
 
 ```js
 function orbitalPeriod(arr) {
-  var GM = 398600.4418;
-  var earthRadius = 6367.4447;
-  var TAU = 2 * Math.PI;
+  const GM = 398600.4418;
+  const earthRadius = 6367.4447;
+  const TAU = 2 * Math.PI;
   return arr.map(function(obj) {
     return {
       name: obj.name,
@@ -73,6 +73,4 @@ function orbitalPeriod(arr) {
     };
   });
 }
-
-orbitalPeriod([{name : "sputkin", avgAlt : 35873.5553}]);
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md
index 03879b19f43..5a26b6e01bf 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md
@@ -61,7 +61,6 @@ function smallestCommons(arr) {
   return arr;
 }
 
-
 smallestCommons([1,5]);
 ```
 
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md
index c74446657ef..9064b93e5df 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md
@@ -103,7 +103,7 @@ assert.deepEqual(
 
 ```js
 function whatIsInAName(collection, source) {
-  var arr = [];
+  const arr = [];
   // Only change code below this line
 
 
@@ -118,8 +118,8 @@ whatIsInAName([{ first: "Romeo", last: "Montague" }, { first: "Mercutio", last:
 
 ```js
 function whatIsInAName(collection, source) {
-  var arr = [];
-  var keys = Object.keys(source);
+  const arr = [];
+  const keys = Object.keys(source);
   collection.forEach(function(e) {
     if(keys.every(function(key) {return e[key] === source[key];})) {
       arr.push(e);
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md
index aee75cf077c..788ac0d9825 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md
@@ -51,7 +51,6 @@ assert(
 
 ```js
 function rot13(str) {
-
   return str;
 }
 
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md
index 1910e938ac6..8896cc86f42 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md
@@ -186,7 +186,7 @@ assert.deepEqual(
 
 ```js
 function checkCashRegister(price, cash, cid) {
-  var change;
+  let change;
   return change;
 }
 
@@ -196,54 +196,57 @@ checkCashRegister(19.5, 20, [["PENNY", 1.01], ["NICKEL", 2.05], ["DIME", 3.1], [
 # --solutions--
 
 ```js
-var denom = [
-    { name: 'ONE HUNDRED', val: 100},
-    { name: 'TWENTY', val: 20},
-    { name: 'TEN', val: 10},
-    { name: 'FIVE', val: 5},
-    { name: 'ONE', val: 1},
-    { name: 'QUARTER', val: 0.25},
-    { name: 'DIME', val: 0.1},
-    { name: 'NICKEL', val: 0.05},
-    { name: 'PENNY', val: 0.01}
+const denom = [
+  { name: "ONE HUNDRED", val: 100 },
+  { name: "TWENTY", val: 20 },
+  { name: "TEN", val: 10 },
+  { name: "FIVE", val: 5 },
+  { name: "ONE", val: 1 },
+  { name: "QUARTER", val: 0.25 },
+  { name: "DIME", val: 0.1 },
+  { name: "NICKEL", val: 0.05 },
+  { name: "PENNY", val: 0.01 },
 ];
 
 function checkCashRegister(price, cash, cid) {
- var output = {status: null, change: []};
- var change = cash - price;
- var register = cid.reduce(function(acc, curr) {
- acc.total += curr[1];
- acc[curr[0]] = curr[1];
- return acc;
- }, {total: 0});
- if(register.total === change) {
- output.status = 'CLOSED';
- output.change = cid;
- return output;
- }
- if(register.total < change) {
- output.status = 'INSUFFICIENT_FUNDS';
- return output;
- }
- var change_arr = denom.reduce(function(acc, curr) {
- var value = 0;
- while(register[curr.name] > 0 && change >= curr.val) {
- change -= curr.val;
- register[curr.name] -= curr.val;
- value += curr.val;
- change = Math.round(change * 100) / 100;
- }
- if(value > 0) {
- acc.push([ curr.name, value ]);
- }
- return acc;
- }, []);
- if(change_arr.length < 1 || change > 0) {
- output.status = 'INSUFFICIENT_FUNDS';
- return output;
- }
- output.status = 'OPEN';
- output.change = change_arr;
- return output;
+  const output = { status: null, change: [] };
+  let change = cash - price;
+  const register = cid.reduce(
+    function (acc, curr) {
+      acc.total += curr[1];
+      acc[curr[0]] = curr[1];
+      return acc;
+    },
+    { total: 0 }
+  );
+  if (register.total === change) {
+    output.status = "CLOSED";
+    output.change = cid;
+    return output;
+  }
+  if (register.total < change) {
+    output.status = "INSUFFICIENT_FUNDS";
+    return output;
+  }
+  const change_arr = denom.reduce(function (acc, curr) {
+    let value = 0;
+    while (register[curr.name] > 0 && change >= curr.val) {
+      change -= curr.val;
+      register[curr.name] -= curr.val;
+      value += curr.val;
+      change = Math.round(change * 100) / 100;
+    }
+    if (value > 0) {
+      acc.push([curr.name, value]);
+    }
+    return acc;
+  }, []);
+  if (change_arr.length < 1 || change > 0) {
+    output.status = "INSUFFICIENT_FUNDS";
+    return output;
+  }
+  output.status = "OPEN";
+  output.change = change_arr;
+  return output;
 }
 ```
diff --git a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md
index 6d4161dd776..61b1c1ab410 100644
--- a/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md
+++ b/curriculum/challenges/italian/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md
@@ -107,8 +107,6 @@ function palindrome(str) {
   return true;
 }
 
-
-
 palindrome("eye");
 ```
 
diff --git a/curriculum/challenges/italian/03-front-end-development-libraries/front-end-development-libraries-projects/build-a-markdown-previewer.md b/curriculum/challenges/italian/03-front-end-development-libraries/front-end-development-libraries-projects/build-a-markdown-previewer.md
index 12727866b5c..85f1049c60c 100644
--- a/curriculum/challenges/italian/03-front-end-development-libraries/front-end-development-libraries-projects/build-a-markdown-previewer.md
+++ b/curriculum/challenges/italian/03-front-end-development-libraries/front-end-development-libraries-projects/build-a-markdown-previewer.md
@@ -22,7 +22,7 @@ Puoi utilizzare qualsiasi mix di HTML, JavaScript, CSS, Bootstrap, SASS, React,
 
 **User Story #4:** Quando inserisco markdown in stile GitHub nell'elemento `#editor`, il testo viene presentato come HTML nell'elemento `#preview` mentre digito (SUGGERIMENTO: Non è necessario che analizzi tu stesso il Markdown - puoi importare la libreria Marked per questo: [https://cdnjs. om/libraries/marked](https://cdnjs.com/libraries/marked)).
 
-**User Story #5:** Quando il mio visualizzatore di markdown viene caricato inizialmente, il testo predefinito nel campo `#editor` dovrebbe contenere markdown valido che rappresenti almeno uno dei seguenti elementi: un'intestazione (dimensione H1), una sotto-intestazione (formato H2), un collegamento, del codice in linea, un blocco di codice, un elemento lista, un blockquote, un'immagine e un testo in grassetto.
+**User Story #5:** Quando il mio visualizzatore di markdown viene caricato inizialmente, il testo predefinito nel campo `#editor` dovrebbe contenere del markdown valido che rappresenti almeno uno dei seguenti elementi: un'intestazione (dimensione H1), una sotto-intestazione (formato H2), un collegamento, del codice in linea, un blocco di codice, un elemento di lista, un blockquote, un'immagine e un testo in grassetto.
 
 **User Story #6:** Quando il mio visualizzatore di markdown viene caricato inizialmente, il markdown predefinito nel campo `#editor` dovrebbe essere presentato come HTML nell'elemento `#preview`.
 
diff --git a/curriculum/challenges/italian/03-front-end-development-libraries/react/access-props-using-this.props.md b/curriculum/challenges/italian/03-front-end-development-libraries/react/access-props-using-this.props.md
index 941b8bf6a03..6e06494d7d0 100644
--- a/curriculum/challenges/italian/03-front-end-development-libraries/react/access-props-using-this.props.md
+++ b/curriculum/challenges/italian/03-front-end-development-libraries/react/access-props-using-this.props.md
@@ -14,67 +14,54 @@ Ogni volta che fai riferimento a un componente di classe all'interno di sé stes
 
 # --instructions--
 
-Mostra un'istanza del componente `ReturnTempPassword` nel componente genitore `ResetPassword`. Qui, dai a `ReturnTempPassword` una prop di `tempPassword` e assegnale un valore stringa di almeno 8 caratteri. All'interno del figlio, `ReturnTempPassword`, accedi alla prop `tempPassword` all'interno dei tag `strong` per assicurarti che l'utente veda la password temporanea.
+Mostra un'istanza del componente `Welcome` nel componente genitore `App`. Qui, dai a `Welcome` una proprietà di `name` e assegnale il valore di una stringa. Dentro il componente figlio, `Welcome`, accedi alla proprietà `name` dentro le tag `strong`.
 
 # --hints--
 
-Il componente `ResetPassword` dovrebbe restituire un singolo elemento `div`.
+Il componente `App` dovrebbe restituire un singolo elemento `div`.
 
 ```js
 assert(
   (function () {
-    const mockedComponent = Enzyme.mount(React.createElement(ResetPassword));
+    const mockedComponent = Enzyme.mount(React.createElement(App));
     return mockedComponent.children().type() === 'div';
   })()
 );
 ```
 
-Il quarto figlio di `ResetPassword` dovrebbe essere il componente `ReturnTempPassword`.
+Il figlio di `App` dovrebbe essere il componente `Welcome`.
 
 ```js
 assert(
   (function () {
-    const mockedComponent = Enzyme.mount(React.createElement(ResetPassword));
+    const mockedComponent = Enzyme.mount(React.createElement(App));
     return (
-      mockedComponent.children().childAt(3).name() === 'ReturnTempPassword'
+      mockedComponent.children().childAt(0).name() === 'Welcome'
     );
   })()
 );
 ```
 
-Il componente `ReturnTempPassword` dovrebbe avere una prop chiamata `tempPassword`.
+Il componente `Welcome` dovrebbe avere una prop chiamata `name`.
 
 ```js
 assert(
   (function () {
-    const mockedComponent = Enzyme.mount(React.createElement(ResetPassword));
-    return mockedComponent.find('ReturnTempPassword').props().tempPassword;
+    const mockedComponent = Enzyme.mount(React.createElement(App));
+    return mockedComponent.find('Welcome').props().name;
   })()
 );
 ```
 
-L'elemento `tempPassword` di `ReturnTempPassword` dovrebbe essere uguale a una stringa di almeno 8 caratteri.
+Il componente `Welcome` dovrebbe visualizzare la stringa che crei come prop `name` all'interno dei tag `strong`.
 
 ```js
 assert(
   (function () {
-    const mockedComponent = Enzyme.mount(React.createElement(ResetPassword));
-    const temp = mockedComponent.find('ReturnTempPassword').props()
-      .tempPassword;
-    return typeof temp === 'string' && temp.length >= 8;
-  })()
-);
-```
-
-Il componente `ReturnTempPassword` dovrebbe visualizzare la password che crei come prop `tempPassword` all'interno dei tag `strong`.
-
-```js
-assert(
-  (function () {
-    const mockedComponent = Enzyme.mount(React.createElement(ResetPassword));
+    const mockedComponent = Enzyme.mount(React.createElement(App));
     return (
       mockedComponent.find('strong').text() ===
-      mockedComponent.find('ReturnTempPassword').props().tempPassword
+      mockedComponent.find('Welcome').props().name
     );
   })()
 );
@@ -85,13 +72,13 @@ assert(
 ## --after-user-code--
 
 ```jsx
-ReactDOM.render(<ResetPassword />, document.getElementById('root'))
+ReactDOM.render(<App />, document.getElementById('root'))
 ```
 
 ## --seed-contents--
 
 ```jsx
-class ReturnTempPassword extends React.Component {
+class App extends React.Component {
   constructor(props) {
     super(props);
 
@@ -100,14 +87,14 @@ class ReturnTempPassword extends React.Component {
     return (
         <div>
             { /* Change code below this line */ }
-            <p>Your temporary password is: <strong></strong></p>
+            <Welcome />
             { /* Change code above this line */ }
         </div>
     );
   }
 };
 
-class ResetPassword extends React.Component {
+class Welcome extends React.Component {
   constructor(props) {
     super(props);
 
@@ -115,11 +102,8 @@ class ResetPassword extends React.Component {
   render() {
     return (
         <div>
-          <h2>Reset Password</h2>
-          <h3>We've generated a new temporary password for you.</h3>
-          <h3>Please reset this password from your account settings ASAP.</h3>
           { /* Change code below this line */ }
-
+          <p>Hello, <strong></strong>!</p>
           { /* Change code above this line */ }
         </div>
     );
@@ -130,7 +114,7 @@ class ResetPassword extends React.Component {
 # --solutions--
 
 ```jsx
-class ReturnTempPassword extends React.Component {
+class Welcome extends React.Component {
   constructor(props) {
     super(props);
 
@@ -138,28 +122,27 @@ class ReturnTempPassword extends React.Component {
   render() {
     return (
         <div>
-            <p>Your temporary password is: <strong>{this.props.tempPassword}</strong></p>
-        </div>
-    );
-  }
-};
-
-class ResetPassword extends React.Component {
-  constructor(props) {
-    super(props);
-
-  }
-  render() {
-    return (
-        <div>
-          <h2>Reset Password</h2>
-          <h3>We've generated a new temporary password for you.</h3>
-          <h3>Please reset this password from your account settings ASAP.</h3>
           { /* Change code below this line */ }
-          <ReturnTempPassword tempPassword="serrPbqrPnzc" />
+          <p>Hello, <strong>{this.props.name}</strong>!</p>
           { /* Change code above this line */ }
         </div>
     );
   }
 };
+
+class App extends React.Component {
+  constructor(props) {
+    super(props);
+
+  }
+  render() {
+    return (
+        <div>
+            { /* Change code below this line */ }
+            <Welcome name="Quincy"/>
+            { /* Change code above this line */ }
+        </div>
+    );
+  }
+};
 ```
diff --git a/curriculum/challenges/italian/03-front-end-development-libraries/react/create-a-controlled-form.md b/curriculum/challenges/italian/03-front-end-development-libraries/react/create-a-controlled-form.md
index fb7db4bdf32..80dce6a8685 100644
--- a/curriculum/challenges/italian/03-front-end-development-libraries/react/create-a-controlled-form.md
+++ b/curriculum/challenges/italian/03-front-end-development-libraries/react/create-a-controlled-form.md
@@ -109,7 +109,7 @@ assert(
 );
 ```
 
-L'intestazione `h1` dovrebbe fare il render del valore del campo `submit` prendendolo dallo stato del componente.
+L'elemento di intestazione `h1` dovrebbe fare il render del valore del campo `submit` prendendolo dallo stato del componente.
 
 ```js
 (() => {
diff --git a/curriculum/challenges/italian/03-front-end-development-libraries/react/create-a-react-component.md b/curriculum/challenges/italian/03-front-end-development-libraries/react/create-a-react-component.md
index 94c7c82f245..dc591f40f68 100644
--- a/curriculum/challenges/italian/03-front-end-development-libraries/react/create-a-react-component.md
+++ b/curriculum/challenges/italian/03-front-end-development-libraries/react/create-a-react-component.md
@@ -38,7 +38,7 @@ Il componente React dovrebbe restituire un elemento `div`.
 assert(Enzyme.shallow(React.createElement(MyComponent)).type() === 'div');
 ```
 
-Il `div` restituito dovrebbe fare il render di un header `h1` al suo interno.
+Il `div` restituito dovrebbe fare il render di un elemento di intestazione `h1` al suo interno.
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/03-front-end-development-libraries/react/render-state-in-the-user-interface-another-way.md b/curriculum/challenges/italian/03-front-end-development-libraries/react/render-state-in-the-user-interface-another-way.md
index f23ecdd208a..20260186715 100644
--- a/curriculum/challenges/italian/03-front-end-development-libraries/react/render-state-in-the-user-interface-another-way.md
+++ b/curriculum/challenges/italian/03-front-end-development-libraries/react/render-state-in-the-user-interface-another-way.md
@@ -27,7 +27,7 @@ assert(
 );
 ```
 
-`MyComponent` dovrebbe presentare un'intestazione `h1` racchiusa in un singolo `div`.
+`MyComponent` dovrebbe presentare un elemento di intestazione `h1` racchiusa in un singolo `div`.
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/03-front-end-development-libraries/react/render-state-in-the-user-interface.md b/curriculum/challenges/italian/03-front-end-development-libraries/react/render-state-in-the-user-interface.md
index 9ff712bae4e..6913dd27e08 100644
--- a/curriculum/challenges/italian/03-front-end-development-libraries/react/render-state-in-the-user-interface.md
+++ b/curriculum/challenges/italian/03-front-end-development-libraries/react/render-state-in-the-user-interface.md
@@ -33,7 +33,7 @@ assert(
 );
 ```
 
-`MyComponent` dovrebbe presentare un'intestazione `h1` racchiusa in un singolo `div`.
+`MyComponent` dovrebbe presentare un elemento di intestazione `h1` racchiusa in un singolo `div`.
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/05-back-end-development-and-apis/basic-node-and-express/use-the-.env-file.md b/curriculum/challenges/italian/05-back-end-development-and-apis/basic-node-and-express/use-the-.env-file.md
index 35036315de6..11ce41eb97d 100644
--- a/curriculum/challenges/italian/05-back-end-development-and-apis/basic-node-and-express/use-the-.env-file.md
+++ b/curriculum/challenges/italian/05-back-end-development-and-apis/basic-node-and-express/use-the-.env-file.md
@@ -22,6 +22,8 @@ Poi, nel gestore della rotta GET `/json` che hai creato nell'ultima sfida, trasf
 
 **Nota:** Se stai usando Replit, non puoi creare un file `.env`. Utilizza invece la scheda <dfn>SECRETS</dfn> integrata per aggiungere la variabile.
 
+Se stai lavorando in locale, avrai bisogno del pacchetto `dotenv`. Carica le variabili ambientali dal tuo file `.env` in `process.env`. Installalo con `npm install dotenv`. Quindi, in cima al tuo file `myApp.js`, importa e carica le variabili con `require('dotenv').config()`.
+
 # --hints--
 
 La risposta dell'endpoint `/json` dovrebbe cambiare in base alla variabile d'ambiente `MESSAGE_STYLE`
diff --git a/curriculum/challenges/italian/09-information-security/information-security-projects/stock-price-checker.md b/curriculum/challenges/italian/09-information-security/information-security-projects/stock-price-checker.md
index d3ca92e3908..6d919bad07c 100644
--- a/curriculum/challenges/italian/09-information-security/information-security-projects/stock-price-checker.md
+++ b/curriculum/challenges/italian/09-information-security/information-security-projects/stock-price-checker.md
@@ -27,6 +27,8 @@ Quando hai finito, assicurati che una demo funzionante del tuo progetto sia ospi
 3.  Aggiungerai tutte le funzionalità di sicurezza a `server.js`
 4.  Creerai tutti i test funzionali in `tests/2_functional-tests.js`
 
+**Nota** Considerazioni sulla privacy: a causa del requisito che solo 1 like per IP dovrebbe essere accettato, è necessario salvare gli indirizzi IP. È importante mantenere il rispetto delle leggi sulla privacy dei dati come il General Data Protection Regulation. Una opzione è quella di ottenere il permesso di salvare i dati dell'utente, ma è molto più semplice anonimizzarlo. Per questa sfida, ricordati di anonimizzare gli indirizzi IP prima di salvarli nel database. Se hai bisogno di idee su come farlo, puoi scegliere di fare l'hash dei dati, troncare l'IP, o impostare parte dell'indirizzo IP a 0.
+
 Scrivi i seguenti test in `tests/2_functional-tests.js`:
 
 -   Visualizzazione di un'azione: richiesta GET a `/api/stock-prices/`
@@ -37,7 +39,7 @@ Scrivi i seguenti test in `tests/2_functional-tests.js`:
 
 # --hints--
 
-Puoi fornire il tuo progetto e non l'URL di esempio.
+È necessario fornire il proprio progetto, non l'URL di esempio.
 
 ```js
 (getUserInput) => {
@@ -110,7 +112,7 @@ async (getUserInput) => {
 };
 ```
 
-Tutti i 5 test funzionali sono completi e superati.
+Tutti i 5 test funzionali richiesti sono completi e superati.
 
 ```js
 async (getUserInput) => {
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/breadth-first-search.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/breadth-first-search.md
index 12070241354..e6840ccd563 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/breadth-first-search.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/breadth-first-search.md
@@ -8,31 +8,31 @@ dashedName: breadth-first-search
 
 # --description--
 
-So far, we've learned different ways of creating representations of graphs. What now? One natural question to have is what are the distances between any two nodes in the graph? Enter <dfn>graph traversal algorithms</dfn>.
+Finora, abbiamo imparato diversi modi per creare rappresentazioni di grafi. E adesso? Una domanda naturale da porsi è quali sono le distanze tra due nodi qualsiasi nel grafo? Qui entrano in gioco gli <dfn>algoritmi di attraversamento di grafi</dfn>.
 
-<dfn>Traversal algorithms</dfn> are algorithms to traverse or visit nodes in a graph. One type of traversal algorithm is the breadth-first search algorithm.
+<dfn>Gli algoritmi di attraversamento</dfn> sono algoritmi per attraversare o visitare nodi in un grafo. Un tipo di algoritmo di attraversamento è l'algoritmo Breadth-first Search (di ricerca in ampiezza).
 
-This algorithm starts at one node and visits all its neighbors that are one edge away. It then goes on to visit each of their neighbors and so on until all nodes have been reached.
+Questo algoritmo inizia da un nodo e visita tutti i suoi vicini che sono ad un arco di distanza. Poi continua a visitare ciascuno dei loro vicini e così via fino a quando tutti i nodi sono stati raggiunti.
 
-An important data structure that will help implement the breadth-first search algorithm is the queue. This is an array where you can add elements to one end and remove elements from the other end. This is also known as a <dfn>FIFO</dfn> or <dfn>First-In-First-Out</dfn> data structure.
+Una struttura dati importante che aiuterà ad implementare l'algoritmo di ricerca in ampiezza è la coda. Questa è un array dove è possibile aggiungere elementi ad una estremità e rimuovere elementi dall'altra estremità. Essa è nota anche come una struttura di dati <dfn>FIFO</dfn> o <dfn>First-In-First-Out</dfn> (NdT: il primo a entrare è il primo a uscire).
 
-Visually, this is what the algorithm is doing. ![Breadth first search algorithm moving through a tree](https://camo.githubusercontent.com/2f57e6239884a1a03402912f13c49555dec76d06/68747470733a2f2f75706c6f61642e77696b696d656469612e6f72672f77696b6970656469612f636f6d6d6f6e732f342f34362f416e696d617465645f4246532e676966)
+Visualmente, questo è ciò che l'algoritmo sta facendo. ![Algoritmo Breadth-first Search che si muove attraverso un albero](https://camo.githubusercontent.com/2f57e6239884a1a03402912f13c49555dec76d06/68747470733a2f2f75706c6f61642e77696b696d656469612e6f72672f77696b6970656469612f636f6d6d6f6e732f342f34362f416e696d617465645f4246532e676966)
 
-The grey shading represents a node getting added into the queue and the black shading represents a node getting removed from the queue. See how every time a node gets removed from the queue (node turns black), all their neighbors get added into the queue (node turns grey).
+L'ombreggiatura grigia rappresenta un nodo che viene aggiunto alla coda e l'ombreggiatura nera rappresenta un nodo che viene rimosso dalla coda. Vedi come ogni volta che un nodo viene rimosso dalla coda (il nodo diventa nero), tutti i vicini vengono aggiunti alla coda (il nodo diventa grigio).
 
-To implement this algorithm, you'll need to input a graph structure and a node you want to start at.
+Per implementare questo algoritmo, dovrai inserire una struttura grafo e un nodo da cui vuoi iniziare.
 
-First, you'll want to be aware of the distances from, or number of edges away from, the start node. You'll want to start all your distances with some large number, like `Infinity`. This prevents counting issues for when a node may not be reachable from your start node. Next, you'll want to go from the start node to its neighbors. These neighbors are one edge away and at this point you should add one unit of distance to the distances you're keeping track of.
+Innanzitutto, dovrai essere consapevole delle distanze (o del numero di archi di distanza) dal nodo iniziale. Ti consigliamo di inizializzare tutte le distanze con un numero elevato, come `Infinity`. Questo impedisce problemi di conteggio per quando un nodo potrebbe non essere raggiungibile dal nodo iniziale. Successivamente, vorrai andare dal nodo iniziale ai suoi vicini. Questi vicini sono a un arco di distanza e a questo punto dovresti aggiungere un'unità di distanza alle distanze di cui stai tenendo traccia.
 
 # --instructions--
 
-Write a function `bfs()` that takes an adjacency matrix graph (a two-dimensional array) and a node label root as parameters. The node label will just be the integer value of the node between `0` and `n - 1`, where `n` is the total number of nodes in the graph.
+Scrivi una funzione `bfs()` che prende un grafo a matrice di adiacenza (un array bidimensionale) e l'etichetta di un nodo radice come parametri. L'etichetta del nodo sarà solo il valore intero del nodo tra `0` e `n - 1`, dove `n` è il numero totale di nodi nel grafico.
 
-Your function will output a JavaScript object key-value pairs with the node and its distance from the root. If the node could not be reached, it should have a distance of `Infinity`.
+La tua funzione produrrà coppie chiave-valore di un oggetto JavaScript con il nodo e la sua distanza dalla radice. Se il nodo non può essere raggiunto, dovrebbe avere una distanza di `Infinity`.
 
 # --hints--
 
-The input graph `[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 1], [0, 0, 1, 0]]` with a start node of `1` should return `{0: 1, 1: 0, 2: 1, 3: 2}`
+Il grafico in ingresso `[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 1], [0, 0, 1, 0]]` con un nodo iniziale di `1` dovrebbe restituire `{0: 1, 1: 0, 2: 1, 3: 2}`
 
 ```js
 assert(
@@ -49,7 +49,7 @@ assert(
 );
 ```
 
-The input graph `[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 0]]` with a start node of `1` should return `{0: 1, 1: 0, 2: 1, 3: Infinity}`
+Il grafico in ingresso `[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 0]]` con un nodo iniziale di `1` dovrebbe restituire `{0: 1, 1: 0, 2: 1, 3: Infinity}`
 
 ```js
 assert(
@@ -66,7 +66,7 @@ assert(
 );
 ```
 
-The input graph `[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 1], [0, 0, 1, 0]]` with a start node of `0` should return `{0: 0, 1: 1, 2: 2, 3: 3}`
+Il grafico in ingresso `[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 1], [0, 0, 1, 0]]` con un nodo iniziale di `0` dovrebbe restituire `{0: 0, 1: 1, 2: 2, 3: 3}`
 
 ```js
 assert(
@@ -83,7 +83,7 @@ assert(
 );
 ```
 
-The input graph `[[0, 1], [1, 0]]` with a start node of `0` should return `{0: 0, 1: 1}`
+Il grafo in ingresso `[[0, 1], [1, 0]]` con un nodo iniziale di `0` dovrebbe restituire `{0: 0, 1: 1}`
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-a-circular-queue.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-a-circular-queue.md
index 16ff688fabf..70828ff286f 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-a-circular-queue.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-a-circular-queue.md
@@ -1,6 +1,6 @@
 ---
 id: 587d8255367417b2b2512c75
-title: Create a Circular Queue
+title: Creare una coda circolare
 challengeType: 1
 forumTopicId: 301625
 dashedName: create-a-circular-queue
@@ -8,9 +8,9 @@ dashedName: create-a-circular-queue
 
 # --description--
 
-In this challenge you will be creating a Circular Queue. A circular queue is a queue that writes to the end of a collection then begins overwriting itself at the beginning of the collection. This type of data structure is useful in certain situations. For example, a circular queue can be used for streaming media. Once the queue is full, new media data will overwrite old data.
+In questa sfida creerai una coda circolare. Una coda circolare è una coda che scrive alla fine di una collezione, poi inizia a sovrascrivere sè stessa all'inizio della collezione. Questo tipo di struttura dati è utile in determinate situazioni. Ad esempio, una coda circolare può essere utilizzata per lo streaming media. Una volta che la coda è piena, i nuovi dati multimediali sovrascriveranno i vecchi dati.
 
-A good way to illustrate this concept is with an array of length `5`:
+Un buon modo per illustrare questo concetto è con un array di lunghezza `5`:
 
 ```js
 [null, null, null, null, null]
@@ -18,7 +18,7 @@ A good way to illustrate this concept is with an array of length `5`:
  ^Write @ 0
 ```
 
-Here the read and write are both at position `0`. Now the queue gets 3 new records `a`, `b`, and `c`. Our queue now looks like:
+Qui la lettura e la scrittura sono entrambe in posizione `0`. Ora la coda ottiene 3 nuovi record `a`, `b`e `c`. La nostra coda ora assomiglia a:
 
 ```js
 [a, b, c, null, null]
@@ -26,7 +26,7 @@ Here the read and write are both at position `0`. Now the queue gets 3 new recor
           ^Write @ 3
 ```
 
-As the read head reads, it can remove values or keep them:
+Come la testa di lettura legge, può remove valori o conservarli:
 
 ```js
 [null, null, null, null, null]
@@ -34,7 +34,7 @@ As the read head reads, it can remove values or keep them:
                    ^Write @ 3
 ```
 
-Now we write the values `d`, `e`, and `f` to the queue. Once the write reaches the end of the array it loops back to the beginning:
+Ora scriviamo i valori `d`, `e` e `f` nella coda. Una volta che la scrittura raggiunge la fine dell'array si riprende dall'inizio:
 
 ```js
 [f, null, null, d, e]
@@ -42,21 +42,21 @@ Now we write the values `d`, `e`, and `f` to the queue. Once the write reaches t
     ^Write @ 1
 ```
 
-This approach requires a constant amount of memory but allows files of a much larger size to be processed.
+Questo approccio richiede una quantità costante di memoria, ma consente di elaborare file di dimensioni molto più grandi.
 
 # --instructions--
 
-In this challenge we will implement a circular queue. The circular queue should provide `enqueue` and `dequeue` methods which allow you to read from and write to the queue. The class itself should also accept an integer argument which you can use to specify the size of the queue when created. We've written the starting version of this class for you in the code editor.
+In questa sfida implementeremo una coda circolare. La coda circolare dovrebbe fornire i metodi `enqueue` e `dequeue` che ti consentono di leggere e scrivere nella coda. La classe stessa dovrebbe anche accettare un argomento intero che puoi usare per specificare la dimensione della coda quando viene creata. Abbiamo scritto per te la versione iniziale di questa classe nell'editor di codice.
 
-When you enqueue items to the queue, the write pointer should advance forward and loop back to the beginning once it reaches the end of the queue. The `enqueue` method should return the item you enqueued if it is successful; otherwise it will return `null`.
+Quando accodi gli elementi alla coda, il puntatore di scrittura dovrebbe andare in avanti e tornare all'inizio una volta che ha raggiunto la fine della coda. Il metodo `enqueue` dovrebbe restituire l'elemento che hai accodato se ha avuto successo; altrimenti restituirà `null`.
 
-Likewise, the read pointer should advance forward as you dequeue items. When you dequeue an item, that item should be returned. If you cannot dequeue an item, you should return `null`.
+Allo stesso modo, il puntatore di lettura dovrebbe avanzare come rimuovi oggetti dalla coda. Quando rimuovi un oggetto dalla coda, quell'oggetto dovrebbe essere restituito. Se non puoi rimuovere un oggetto dalla coda, dovresti restituire `null`.
 
-The write pointer should not be allowed to move past the read pointer (our class won't let you overwrite data you haven't read yet) and the read pointer should not be able to advance past data you have written.
+Al puntatore di scrittura non dovrebbe essere permesso di muovere oltre il puntatore di lettura (la nostra classe non ti permetterà di sovrascrivere dati che non sono ancora stati letti) e il puntatore di lettura non dovrebbe eessere in grado di andare oltre i dati che hai scritto.
 
 # --hints--
 
-The `enqueue` method should add items to the circular queue.
+Il metodo `enqueue` dovrebbe aggiungere elementi alla coda circolare.
 
 ```js
 assert(
@@ -71,7 +71,7 @@ assert(
 );
 ```
 
-You should not enqueue items past the read pointer.
+Non dovresti accodare gli elementi oltre il puntatore di lettura.
 
 ```js
 assert(
@@ -89,7 +89,7 @@ assert(
 );
 ```
 
-The `dequeue` method should dequeue items from the queue.
+Il metodo `dequeue` dovrebbe rimuovere elementi dalla coda.
 
 ```js
 assert(
@@ -105,7 +105,7 @@ assert(
 );
 ```
 
-After an item is dequeued, its position in the queue should be reset to `null`.
+Dopo che un elemento è stato rimosso dalla coda, la sua posizione nella coda dovrebbe essere resettata su `null`.
 
 ```js
 assert(
@@ -122,7 +122,7 @@ assert(
 );
 ```
 
-Trying to dequeue past the write pointer should return `null` and does not advance the write pointer.
+Tentare di rimuovere oggetti dalla coda oltre il puntatore di scrittura dovrebbe restituire `null` e non far avanzare il puntatore di scrittura.
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-a-hash-table.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-a-hash-table.md
index a33c3d51787..fdbabbfa61a 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-a-hash-table.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-a-hash-table.md
@@ -1,6 +1,6 @@
 ---
 id: 587d825b367417b2b2512c8e
-title: Create a Hash Table
+title: Creare una tabella hash
 challengeType: 1
 forumTopicId: 301627
 dashedName: create-a-hash-table
@@ -8,23 +8,23 @@ dashedName: create-a-hash-table
 
 # --description--
 
-In this challenge we will learn about hash tables. A Hash table is used to implement associative arrays, or mappings of key-value pairs, like the objects and Maps we have just been studying. A JavaScript object could be implemented as a hash table, for instance (its actual implementation will depend on the environment it's running in). The way a hash table works is that it takes a key input and hashes this key in a deterministic way to some numerical value. This numerical value is then used as the actual key the associated value is stored by. Then, if you try to access the same key again, the hashing function will process the key, return the same numerical result, which will then be used to look up the associated value. This provides very efficient O(1) lookup time on average.
+In questa sfida conosceremo le tabelle hash. Una tabella hash viene utilizzata per implementare array associativi, o mappature di coppie chiave-valore, come gli oggetti e le mappe che abbiamo appena studiato. Un oggetto JavaScript ad esempio potrebbe essere implementato come una tabella hash (la sua effettiva implementazione dipenderà dall'ambiente in esecuzione). Il modo in cui funziona una tabella di hash è che richiede un input chiave e fa hash di questa chiave in modo deterministico ad un certo valore numerico. Questo valore numerico viene quindi utilizzato come chiave reale con cui viene memorizzato il valore associato. Quindi, se si tenta di accedere di nuovo alla stessa chiave, la funzione di hash elaborerà la chiave, restituirà lo stesso risultato numerico, che verrà poi utilizzato per cercare il valore associato. Questo fornisce un tempo di ricerca O(1) molto efficiente in media.
 
-Hash tables can be implemented as arrays with hash functions producing array indices within a specified range. In this method, the choice of the array size is important, as is the hashing function. For instance, what if the hashing function produces the same value for two different keys? This is called a collision. One way to handle collisions is to just store both key-value pairs at that index. Then, upon lookup of either, you would have to iterate through the bucket of items to find the key you are looking for. A good hashing function will minimize collisions to maintain efficient search time.
+Le tabelle di hash possono essere implementate come array con funzioni di hash che producono indici array all'interno di un intervallo specificato. In questo metodo, la scelta della dimensione dell'array è importante, così come la funzione di hashing. Per esempio, cosa succede se la funzione di hashing produce lo stesso valore per due chiavi diverse? Questa si chiama collisione. Un modo per gestire le collisioni è quello di semplicemente memorizzare entrambe le coppie chiave-valore in quell'indice. Poi, alla ricerca di entrambi, si dovrebbe iterare attraverso il gruppo di oggetti per trovare la chiave che stai cercando. Una buona funzione di hashing minimizzerà le collisioni per mantenere il tempo di ricerca efficiente.
 
-Here, we won't be concerned with the details of hashing or hash table implementation, we will just try to get a general sense of how they work.
+Risultati della traduzione Qui non ci occuperemo dei dettagli dell'hashing o dell'implementazione della tabella hash, cercheremo solo di avere un'idea generale di come funzionano.
 
 # --instructions--
 
-Let's create the basic functionality of a hash table. We've created a naive hashing function for you to use. You can pass a string value to the function `hash` and it will return a hashed value you can use as a key for storage. Store items based on this hashed value in the `this.collection` object. Create these three methods: `add`, `remove`, and `lookup`. The first should accept a key value pair to add to the hash table. The second should remove a key-value pair when passed a key. The third should accept a key and return the associated value or `null` if the key is not present.
+Creiamo la funzionalità di base di una tabella di hash. Abbiamo creato una funzione di hashing ingenua da usare. Puoi passare un valore di stringa alla funzione `hash` e restituirà un valore hashed che puoi usare come chiave per l'archiviazione. Memorizza gli oggetti in base a questo valore hashed nell'oggetto `this.collection`. Crea questi tre metodi: `add`, `remove` e `lookup`. Il primo dovrebbe accettare una coppia di valori chiave da aggiungere alla tabella hash. Il secondo dovrebbe rimuovere una coppia chiave-valore quando riceve una chiave. Il terzo dovrebbe accettare una chiave e restituire il valore associato o `null` se la chiave non è presente.
 
-Be sure to write your code to account for collisions!
+Assicurati di scrivere il tuo codice per gestire le collisioni!
 
-**Note:** The `remove` method tests won't pass until the `add` and `lookup` methods are correctly implemented.
+**Nota:** I test del metodo `remove` non passeranno fino a quando i metodi `add` e `lookup` non saranno correttamente implementati.
 
 # --hints--
 
-The HashTable data structure should exist.
+La struttura di dati HashTable dovrebbe esistere.
 
 ```js
 assert(
@@ -38,7 +38,7 @@ assert(
 );
 ```
 
-The HashTable should have an add method.
+L'HashTable dovrebbe avere un metodo add.
 
 ```js
 assert(
@@ -52,7 +52,7 @@ assert(
 );
 ```
 
-The HashTable should have a lookup method.
+L'HashTable dovrebbe avere un metodo lookup.
 
 ```js
 assert(
@@ -66,7 +66,7 @@ assert(
 );
 ```
 
-The HashTable should have a remove method.
+L'HashTable dovrebbe avere un metodo remove.
 
 ```js
 assert(
@@ -80,7 +80,7 @@ assert(
 );
 ```
 
-The add method should add key value pairs and the lookup method should return the values associated with a given key.
+Il metodo add dovrebbe aggiungere coppie chiave-valore e il metodo di ricerca dovrebbe restituire i valori associati a una determinata chiave.
 
 ```js
 assert(
@@ -95,7 +95,7 @@ assert(
 );
 ```
 
-The remove method should accept a key as input and should remove the associated key value pair.
+Il metodo di rimozione dovrebbe accettare una chiave come input e dovrebbe rimuovere la coppia chiave-valore associata.
 
 ```js
 assert(
@@ -113,7 +113,7 @@ assert(
 );
 ```
 
-The remove method should only remove the correct key value pair.
+Il metodo di rimozione dovrebbe rimuovere solo la coppia chiave-valore corretta.
 
 ```js
 assert(
@@ -139,7 +139,7 @@ assert(
 );
 ```
 
-Items should be added using the hash function.
+Gli elementi devono essere aggiunti usando la funzione hash.
 
 ```js
 assert(
@@ -157,7 +157,7 @@ assert(
 );
 ```
 
-The hash table should handle collisions.
+La tabella di hash dovrebbe gestire le collisioni.
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-a-queue-class.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-a-queue-class.md
index b167ebfcdf2..6f608044276 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-a-queue-class.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-a-queue-class.md
@@ -1,6 +1,6 @@
 ---
 id: 587d8250367417b2b2512c60
-title: Creare una classe Coda
+title: Creare una classe Queue
 challengeType: 1
 forumTopicId: 301631
 dashedName: create-a-queue-class
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-a-trie-search-tree.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-a-trie-search-tree.md
index fb838c883e0..4afbd6a3701 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-a-trie-search-tree.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-a-trie-search-tree.md
@@ -1,6 +1,6 @@
 ---
 id: 587d8259367417b2b2512c84
-title: Create a Trie Search Tree
+title: Crea un albero di ricerca Trie
 challengeType: 1
 forumTopicId: 301634
 dashedName: create-a-trie-search-tree
@@ -8,15 +8,15 @@ dashedName: create-a-trie-search-tree
 
 # --description--
 
-Here we will move on from binary search trees and take a look at another type of tree structure called a trie. A trie is an ordered search tree commonly used to hold strings, or more generically associative arrays or dynamic datasets in which the keys are strings. They are very good at storing sets of data when many keys will have overlapping prefixes, for example, all the words in a dictionary. Unlike a binary tree, nodes are not associated with actual values. Instead, the path to a node represents a specific key. For instance, if we wanted to store the string code in a trie, we would have four nodes, one for each letter: c — o — d — e. Following that path through all these nodes will then create code as a string — that path is the key we stored. Then, if we wanted to add the string coding, it would share the first three nodes of code before branching away after the d. In this way, large datasets can be stored very compactly. In addition, search can be very quick because it is effectively limited to the length of the string you are storing. Furthermore, unlike binary trees a node can store any number of child nodes. As you might have guessed from the above example, some metadata is commonly stored at nodes that hold the end of a key so that on later traversals that key can still be retrieved. For instance, if we added codes in our example above we would need some way to know that the e in code represents the end of a key that was previously entered. Otherwise, this information would effectively be lost when we add codes.
+Qui ci muoveremo dagli alberi di ricerca binari e daremo un'occhiata ad un altro tipo di struttura ad albero chiamato trie. Un trie è un albero di ricerca ordinato comunemente usato per contenere stringhe, o più generamente array associativi o dataset dinamici in cui le chiavi sono stringhe. Sono un ottimo modo per immagazzinare set di dati quando molte chiavi hanno prefissi che si sovrappongono, per esempio, tutte le parole in un dizionario. A differenza di un albero binario, i nodi non sono associati con valori. Invece, il percorso verso un nodo rappresenta una chiave specifica. Per esempio, se vogliamo salvare la stringa "code" in un trie, avremmo quattri nodi, uno per ogni lettera: c — o — d — e. Seguendo il percorso attraverso tutti questi nodi creerà la stringa "code" — quel percorso è la chiave che abbiamo immagazzinato. Quindi, se vogliamo aggiungere la stringa "coding", avrebbe in comune i primi tre nodi di "code" prima di seguire un altro ramo dopo la d. In questo modo, dataset ampi possono essere immagazzinati in maniera compatta. In aggiunta, una ricerca può essere molto veloce perché è effettivamente limitata alla lunghezza della stringa che stai immagazinnando. Inoltre, a differenza degli alberi binari un nodo può avere qualsiasi numero di nodi figli. Come potresti avere indovinato dall'esempio precedente, alcuni metadata sono comunemente salvati come nodi che contengono la fine della chiave cossicché in traversamenti succestivi la chiave può essere ancora recuperata. Per esempio, se avessimo aggiunto "codes" nell'esempio precedente, avremmo avuto bisogno di qualche modo per sapere che la e in "code" rappresenta la fine di una chiave che era stata inserita precedentemente. Altrimenti, questa informazione andrebbe persa quando aggiungiamo "codes".
 
 # --instructions--
 
-Let's create a trie to store words. It will accept words through an `add` method and store these in a trie data structure. It will also allow us to query if a given string is a word with an `isWord` method, and retrieve all the words entered into the trie with a `print` method. `isWord` should return a boolean value and print should return an array of all these words as string values. In order for us to verify that this data structure is implemented correctly, we've provided a `Node` structure for each node in the tree. Each node will be an object with a `keys` property which is a JavaScript Map object. This will hold the individual letters that are valid keys of each node. We've also created an `end` property on the nodes that can be set to `true` if the node represents the termination of a word.
+Creiamo un trie per memorizzare parole. Accetterà parole attraverso un metodo `add` e salverà queste parole in una struttura dati trie. Permetterà anche di chiedere se una certa stringa è una parola con un metodo `isWord`, e estrarre tutte le parole inserite nel trie con un metodo `print`. `isWord` dovrebbe restituire un valore booleano e print dovrebbe restituire un array di tutte queste parole come stringhe. Per poter verificare che la struttura dati è implementata correttamente, abbiamo provveduto una struttura `Node` per ogni nodo dell'albero. Ogni nodo sarà un oggetto con una proprietà `keys` che è un oggetto Map JavaScript. Questo conterrà le lettere individuali che sono chiavi valide per ogni nodo. Abbiamo anche creato una proprietà `end` nel nodo che può essere messa su `true` se il nodo rappresenta la terminazione di una parola.
 
 # --hints--
 
-The Trie should have an add method.
+Il Trie dovrebbe avere un metodo add.
 
 ```js
 assert(
@@ -32,7 +32,7 @@ assert(
 );
 ```
 
-The Trie should have a print method.
+Il Trie dovrebbe avere un metodo print.
 
 ```js
 assert(
@@ -48,7 +48,7 @@ assert(
 );
 ```
 
-The Trie should have an isWord method.
+Il Trie dovrebbe avere un metodo isWord.
 
 ```js
 assert(
@@ -64,7 +64,7 @@ assert(
 );
 ```
 
-The print method should return all items added to the trie as strings in an array.
+Il metodo print dovrebbe restituire tutti gli elementi aggiunti al trie come stringhe in un array.
 
 ```js
 assert(
@@ -93,7 +93,7 @@ assert(
 );
 ```
 
-The isWord method should return true only for words added to the trie and false for all other words.
+Il metodo isWord dovrebbe restituire vero solo per le parole aggiunte al trie e falso per tutte le altre parole.
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-an-es6-javascript-map.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-an-es6-javascript-map.md
index 7e6822ef676..1a6ec608b34 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-an-es6-javascript-map.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-an-es6-javascript-map.md
@@ -1,6 +1,6 @@
 ---
 id: 587d825b367417b2b2512c8d
-title: Create an ES6 JavaScript Map
+title: Creare una mappa JavaScript ES6
 challengeType: 1
 forumTopicId: 301635
 dashedName: create-an-es6-javascript-map
@@ -8,21 +8,21 @@ dashedName: create-an-es6-javascript-map
 
 # --description--
 
-The new version of JavaScript provides us with a built-in Map object which provides much of the functionality we wrote by hand in the last challenge. This Map object, although similar to regular JavaScript objects, provides some useful functionality that normal objects lack. For example, an ES6 Map tracks the insertion order of items that are added to it. Here is a more complete overview of its methods: `.has(key)` returns true or false based on the presence of a key `.get(key)` returns the value associated with a key `.set(key, value)` sets a new key, value pair `.delete(key)` removes a key, value pair `.clear()` removes all key, value pairs `.entries()` returns an array of all the keys in insertion order `.values()` returns an array of all the values in insertion order
+La nuova versione di JavaScript ci fornisce un oggetto Map incorporato che fornisce gran parte delle funzionalità che abbiamo scritto a mano nell'ultima sfida. Questo oggetto Map, anche se simile a oggetti JavaScript regolari, fornisce alcune funzionalità utili che agli oggetti normali mancano. Ad esempio, una Map ES6 tiene in memoria l'ordine di inserimento degli elementi che vengono aggiunti. Ecco una panoramica più completa dei suoi metodi: `.has(key)` restituisce true o false in base alla presenza di una chiave `.get(key)` restituisce il valore associato con una chiave `.set(key, value)` aggiunge una nuova coppia chiave-valore `.delete(key)` rimuove una coppia chiave-valore `.clear()` rimuove tutte le coppie chiave-valore `.entries()` restituisce un array con tutte le chiavi in ordine di inserimento `.values()` restituisce un array con tutti i valori in ordine di inserzione
 
 # --instructions--
 
-Define a JavaScript Map object and assign to it a variable called myMap. Add the key, value pair `freeCodeCamp`, `Awesome!` to it.
+Definisci un oggetto Map JavaScript e assegna ad esso una variabile chiamata myMap. Aggiungi la coppia chiave-valore `freeCodeCamp`, `Awesome!` ad esso.
 
 # --hints--
 
-The myMap object should exist.
+L'oggetto myMap dovrebbe esistere.
 
 ```js
 assert(typeof myMap === 'object');
 ```
 
-myMap should contain the key value pair `freeCodeCamp`, `Awesome!`.
+myMap dovrebbe contenere la coppia chiave-valore `freeCodeCamp`, `Awesome!`.
 
 ```js
 assert(myMap.get('freeCodeCamp') === 'Awesome!');
@@ -39,5 +39,7 @@ assert(myMap.get('freeCodeCamp') === 'Awesome!');
 # --solutions--
 
 ```js
-// solution required
+const myMap = new Map();
+
+myMap.set("freeCodeCamp", "Awesome!");
 ```
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-and-add-to-sets-in-es6.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-and-add-to-sets-in-es6.md
index 1727a24ed00..04ff67a6d87 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-and-add-to-sets-in-es6.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/create-and-add-to-sets-in-es6.md
@@ -1,6 +1,6 @@
 ---
 id: 587d8254367417b2b2512c70
-title: Create and Add to Sets in ES6
+title: Creare e aggiungere ai set in ES6
 challengeType: 1
 forumTopicId: 301636
 dashedName: create-and-add-to-sets-in-es6
@@ -8,34 +8,34 @@ dashedName: create-and-add-to-sets-in-es6
 
 # --description--
 
-Now that you have worked through ES5, you are going to perform something similar in ES6. This will be considerably easier. ES6 contains a built-in data structure `Set` so many of the operations you wrote by hand are now included for you. Let's take a look:
+Ora che avete lavorato su ES5, state per eseguire qualcosa di simile in ES6. Questo sarà molto più facile. ES6 contiene una struttura di dati integrata `Set` quindi molte delle operazioni che hai scritto a mano sono ora incluse per te. Diamo un'occhiata:
 
-To create a new empty set:
+Per creare un nuovo set vuoto:
 
 ```js
 var set = new Set();
 ```
 
-You can create a set with a value:
+È possibile creare un set con un valore:
 
 ```js
 var set = new Set(1);
 ```
 
-You can create a set with an array:
+È possibile creare un set con un array:
 
 ```js
 var set = new Set([1, 2, 3]);
 ```
 
-Once you have created a set, you can add the values you wish using the `add` method:
+Una volta creato un set, puoi aggiungere i valori che desideri utilizzando il metodo `add`:
 
 ```js
 var set = new Set([1, 2, 3]);
 set.add([4, 5, 6]);
 ```
 
-As a reminder, a set is a data structure that cannot contain duplicate values:
+Come promemoria, un insieme è una struttura di dati che non può contenere valori duplicati:
 
 ```js
 var set = new Set([1, 2, 3, 1, 2, 3]);
@@ -44,11 +44,11 @@ var set = new Set([1, 2, 3, 1, 2, 3]);
 
 # --instructions--
 
-For this exercise, return a set with the following values: `1, 2, 3, 'Taco', 'Cat', 'Awesome'`
+Per questo esercizio, restituisci un set con i seguenti valori: `1, 2, 3, 'Taco', 'Cat', 'Awesome'`
 
 # --hints--
 
-Your `Set` should only contain the values `1, 2, 3, Taco, Cat, Awesome`.
+Il tuo `Set` deve contenere solo i valori `1, 2, 3, Taco, Cat, Awesome`.
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/delete-a-leaf-node-in-a-binary-search-tree.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/delete-a-leaf-node-in-a-binary-search-tree.md
index 7aa19f4c83c..1a422ae4b2c 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/delete-a-leaf-node-in-a-binary-search-tree.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/delete-a-leaf-node-in-a-binary-search-tree.md
@@ -46,6 +46,25 @@ assert(
 );
 ```
 
+Tentare di rimuovere un elemento da un albero vuoto dovrebbe restituire `null`.
+
+```js
+assert(
+  (function () {
+    var test = false;
+    if (typeof BinarySearchTree !== 'undefined') {
+      test = new BinarySearchTree();
+    } else {
+      return false;
+    }
+    if (typeof test.remove !== 'function') {
+      return false;
+    }
+    return test.remove(100) == null;
+  })()
+);
+```
+
 Tentare di rimuovere un elemento che non esiste dovrebbe restituire `null`.
 
 ```js
@@ -60,6 +79,8 @@ assert(
     if (typeof test.remove !== 'function') {
       return false;
     }
+    test.add(15);
+    test.add(30);
     return test.remove(100) == null;
   })()
 );
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/find-the-minimum-and-maximum-height-of-a-binary-search-tree.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/find-the-minimum-and-maximum-height-of-a-binary-search-tree.md
index eb71f5ea47f..8e7556d3503 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/find-the-minimum-and-maximum-height-of-a-binary-search-tree.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/find-the-minimum-and-maximum-height-of-a-binary-search-tree.md
@@ -1,6 +1,6 @@
 ---
 id: 587d8257367417b2b2512c7d
-title: Find the Minimum and Maximum Height of a Binary Search Tree
+title: Trovare l'altezza minima e massima di un albero binario di ricerca
 challengeType: 1
 forumTopicId: 301641
 dashedName: find-the-minimum-and-maximum-height-of-a-binary-search-tree
@@ -8,19 +8,19 @@ dashedName: find-the-minimum-and-maximum-height-of-a-binary-search-tree
 
 # --description--
 
-In the last challenge we described a scenario in which a tree could become unbalanced. To understand the concept of balance, let's take a look at another tree property: height. Height in a tree represents the distance from the root node to any given leaf node. Different paths in a highly branched tree structure may have different heights, but for a given tree there will be a minimum and maximum height. If the tree is balanced, these values will differ at most by one. This means that in a balanced tree, all the leaf nodes exist within the same level, or if they are not within the same level they are at most one level apart.
+Nell'ultima sfida abbiamo descritto uno scenario in cui un albero potrebbe diventare squilibrato. Per capire il concetto di equilibrio, diamo un'occhiata ad un'altra proprietà dell'albero: l'altezza. L'altezza in un albero rappresenta la distanza dal nodo radice a qualsiasi nodo foglia. Percorsi diversi in una struttura ad albero altamente ramificato possono avere altezze diverse, ma per un dato albero ci sarà un'altezza minima e una massima. Se l'albero è bilanciato, questi valori differiranno al massimo di uno. Ciò significa che in un albero bilanciato, tutti i nodi delle foglie sono allo stesso livello, o al massimo a un livello di distanza.
 
-The property of balance is important for trees because it is what determines the efficiency of tree operations. As we explained in the last challenge, we face worst case time complexity for heavily unbalanced trees. Self-balancing trees are commonly used to account for this issue in trees with dynamic data sets. Common examples of these include AVL trees, red-black trees, and B-trees. These trees all contain additional internal logic which re-balance the tree when insertions or deletions create a state of imbalance.
+La proprietà dell'equilibrio è importante per gli alberi perché è ciò che determina l'efficienza delle operazioni su di essi. Come abbiamo spiegato nell'ultima sfida, per alberi fortemente squilibrati ci troviamo di fronte alla peggiore complessità temporale. Gli alberi auto-bilancianti sono comunemente utilizzati per tenere conto di questo problema in alberi con serie di dati dinamici. Esempi comuni di questi includono gli alberi AVL, gli alberi rosso-neri e gli alberi B. Tutti questi alberi contengono una logica interna aggiuntiva che riequilibra l'albero quando inserzioni o cancellazioni creano uno stato di squilibrio.
 
-**Note:** A similar property to height is depth, which refers to how far a given node is from the root node.
+**Nota:** Una proprietà simile all'altezza è la profondità, che si riferisce a quanto un dato nodo è lontano dal nodo radice.
 
 # --instructions--
 
-Write two methods for our binary tree: `findMinHeight` and `findMaxHeight`. These methods should return an integer value for the minimum and maximum height within a given binary tree, respectively. If the node is empty let's assign it a height of `-1` (that's the base case). Finally, add a third method `isBalanced` which returns `true` or `false` depending on whether the tree is balanced or not. You can use the first two methods you just wrote to determine this.
+Scrivi due metodi per il nostro albero binario: `findMinHeight` e `findMaxHeight`. Questi metodi dovrebbero restituire un valore intero per l'altezza minima e massima all'interno di un dato albero binario, rispettivamente. Se il nodo è vuoto, assegniamogli un'altezza di `-1` (questo è il caso di base). Infine, aggiungi un terzo metodo `isBalanced` che restituisce `true` o `false` a seconda che l'albero sia bilanciato o meno. È possibile utilizzare i primi due metodi che hai appena scritto per determinarlo.
 
 # --hints--
 
-The `BinarySearchTree` data structure should exist.
+La struttura di dati `BinarySearchTree` dovrebbe esistere.
 
 ```js
 assert(
@@ -34,7 +34,7 @@ assert(
 );
 ```
 
-The binary search tree should have a method called `findMinHeight`.
+L'albero binario di ricerca dovrebbe avere un metodo chiamato `findMinHeight`.
 
 ```js
 assert(
@@ -50,7 +50,7 @@ assert(
 );
 ```
 
-The binary search tree should have a method called `findMaxHeight`.
+L'albero binario di ricerca dovrebbe avere un metodo chiamato `findMaxHeight`.
 
 ```js
 assert(
@@ -66,7 +66,7 @@ assert(
 );
 ```
 
-The binary search tree should have a method called `isBalanced`.
+L'albero binario di ricerca dovrebbe avere un metodo chiamato `isBalanced`.
 
 ```js
 assert(
@@ -82,7 +82,7 @@ assert(
 );
 ```
 
-The `findMinHeight` method should return the minimum height of the tree.
+Il metodo `findMinHeight` deve restituire l'altezza minima dell'albero.
 
 ```js
 assert(
@@ -109,7 +109,7 @@ assert(
 );
 ```
 
-The `findMaxHeight` method should return the maximum height of the tree.
+Il metodo `findMaxHeight` deve restituire l'altezza massima dell'albero.
 
 ```js
 assert(
@@ -136,7 +136,7 @@ assert(
 );
 ```
 
-An empty tree should return a height of `-1`.
+Un albero vuoto dovrebbe restituire un'altezza di `-1`.
 
 ```js
 assert(
@@ -155,7 +155,7 @@ assert(
 );
 ```
 
-The `isBalanced` method should return `false` if the tree is an unbalanced binary search tree.
+Il metodo `isBalanced` dovrebbe restituire `false` se l'albero è un albero binario di ricerca sbilanciato.
 
 ```js
 assert(
@@ -182,7 +182,7 @@ assert(
 );
 ```
 
-The `isBalanced` method should return `true` if the tree is a balanced binary search tree.
+Il metodo `isBalanced` dovrebbe restituire `true` se l'albero è un albero binario di ricerca equilibrato.
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/find-the-minimum-and-maximum-value-in-a-binary-search-tree.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/find-the-minimum-and-maximum-value-in-a-binary-search-tree.md
index 23077f9d938..127b719edcf 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/find-the-minimum-and-maximum-value-in-a-binary-search-tree.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/find-the-minimum-and-maximum-value-in-a-binary-search-tree.md
@@ -1,6 +1,6 @@
 ---
 id: 587d8256367417b2b2512c7a
-title: Find the Minimum and Maximum Value in a Binary Search Tree
+title: Trovare i valori minimo e massimo di un albero binario di ricerca
 challengeType: 1
 forumTopicId: 301642
 dashedName: find-the-minimum-and-maximum-value-in-a-binary-search-tree
@@ -8,11 +8,11 @@ dashedName: find-the-minimum-and-maximum-value-in-a-binary-search-tree
 
 # --description--
 
-In this challenge you will define two methods, `findMin` and `findMax`. These methods should return the minimum and maximum value held in the binary search tree (don't worry about adding values to the tree for now, we have added some in the background). If you get stuck, reflect on the invariant that must be true for binary search trees: each left subtree is less than or equal to its parent and each right subtree is greater than or equal to its parent. Let's also say that our tree can only store integer values. If the tree is empty, either method should return `null`.
+In questa sfida definirai due metodi, `findMin` e `findMax`. Questi metodi dovrebbero restituire il valore minimo e massimo contenuto nell'albero binario di ricerca (non preoccuparti di aggiungere valori all'albero per ora, ne abbiamo aggiunti alcuni in background). Se si rimani bloccato, rifletti sull'invariante che deve essere vera per gli alberi di ricerca binari: ogni sottoalbero sinistro è inferiore o uguale al suo genitore e ogni sottoalbero destro è maggiore o uguale al suo genitore. Diciamo anche che il nostro albero può memorizzare solo valori interi. Se l'albero è vuoto, uno dei due metodi dovrebbe restituire `null`.
 
 # --hints--
 
-The `BinarySearchTree` data structure should exist.
+La struttura di dati `BinarySearchTree` dovrebbe esistere.
 
 ```js
 assert(
@@ -26,7 +26,7 @@ assert(
 );
 ```
 
-The binary search tree should have a method called `findMin`.
+L'albero binario di ricerca dovrebbe avere un metodo chiamato `findMin`.
 
 ```js
 assert(
@@ -42,7 +42,7 @@ assert(
 );
 ```
 
-The binary search tree should have a method called `findMax`.
+L'albero di ricerca binario dovrebbe avere un metodo chiamato `findMax`.
 
 ```js
 assert(
@@ -58,7 +58,7 @@ assert(
 );
 ```
 
-The `findMin` method should return the minimum value in the binary search tree.
+Il metodo `findMin` dovrebbe restituire il valore minimo nell'albero binario di ricerca.
 
 ```js
 assert(
@@ -85,7 +85,7 @@ assert(
 );
 ```
 
-The `findMax` method should return the maximum value in the binary search tree.
+Il metodo `findMax` dovrebbe restituire il valore massimo nell'albero binario di ricerca.
 
 ```js
 assert(
@@ -112,7 +112,7 @@ assert(
 );
 ```
 
-The `findMin` and `findMax` methods should return `null` for an empty tree.
+I metodi `findMin` e `findMax` dovrebbero restituire `null` per un albero vuoto.
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/implement-heap-sort-with-a-min-heap.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/implement-heap-sort-with-a-min-heap.md
index 158817a64db..317d7da3eca 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/implement-heap-sort-with-a-min-heap.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/implement-heap-sort-with-a-min-heap.md
@@ -1,6 +1,6 @@
 ---
 id: 587d825b367417b2b2512c8c
-title: Implement Heap Sort with a Min Heap
+title: Implementa un Heap Sort con un Min Heap
 challengeType: 1
 forumTopicId: 301643
 dashedName: implement-heap-sort-with-a-min-heap
@@ -8,17 +8,17 @@ dashedName: implement-heap-sort-with-a-min-heap
 
 # --description--
 
-Now that we can add and remove elements let's see some of the applications heaps can be used for. Heaps are commonly used to implement priority queues because they always store an item of greatest or least value in first position. In addition, they are used to implement a sorting algorithm called heap sort. We'll see how to do this here. Heap sort uses a min heap, the reverse of a max heap. A min heap always stores the element of least value in the root position.
+Ora che possiamo aggiungere e rimuovere elementi vediamo alcune applicazioni per cui gli heap possono essere usati. Gli heap sono comunemente usati per implementare file di priorità perché immagazzinano sempre un elemento di valore massimo o minimo nella prima posizione. In aggiunta, sono usati per implementare un algoritmo di ordinamento chiamato heap sort. Vedremo come farlo qui. Heap sort usa un min heap, l'opposto di un max heap. Un min heap ha sempre l'elemento di valore minore nella posizione root.
 
-Heap sort works by taking an unsorted array, adding each item in the array into a min heap, and then extracting every item out of the min heap into a new array. The min heap structure ensures that the new array will contain the original items in least to greatest order. This is one of the most efficient sorting algorithms with average and worst case performance of O(nlog(n)).
+Heap sort funziona prendendo un array non ordinato, aggiungendo ogni elemento dell'array in un min heap, e poi estraendo ogni elemento dal min heap in un array. La struttura min heap assicura che il nuovo array conterra gli elementi originali in ordine dal più piccolo al più grande. Questo è uno degli algoritmi per ordinare più efficienti con una performance media e nel peggiore dei casi di O(nlog(n)).
 
 # --instructions--
 
-Let's implement heap sort with a min heap. Feel free to adapt your max heap code here. Create an object `MinHeap` with `insert`, `remove`, and `sort` methods. The `sort` method should return an array of all the elements in the min heap sorted from smallest to largest.
+Implementa un heap sort con un min heap. Adatta liberamente il codice del tuo max heap qui. Crea un oggetto `MinHeap` con metodi `insert`, `remove`, e `sort`. Il metodo `sort` dovrebbe restituire un array degli elementi nel min heap ordinati dal più piccolo al più grande.
 
 # --hints--
 
-The MinHeap data structure should exist.
+La struttura dati MinHeap dovrebbe esistere.
 
 ```js
 assert(
@@ -32,7 +32,7 @@ assert(
 );
 ```
 
-MinHeap should have a method called insert.
+MinHeap dovrebbe avere un metodo chiamato insert.
 
 ```js
 assert(
@@ -48,7 +48,7 @@ assert(
 );
 ```
 
-MinHeap should have a method called remove.
+MinHeap dovrebbe avere un metodo chiamato remove.
 
 ```js
 assert(
@@ -64,7 +64,7 @@ assert(
 );
 ```
 
-MinHeap should have a method called sort.
+MinHeap dovrebbe avere un metodo chiamato sort.
 
 ```js
 assert(
@@ -80,7 +80,7 @@ assert(
 );
 ```
 
-The sort method should return an array containing all items added to the min heap in sorted order.
+Il metodo sort dovrebbe restituire un array che continuete tutto gli elementi aggiunti al min heap ordinati.
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/insert-an-element-into-a-max-heap.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/insert-an-element-into-a-max-heap.md
index e20657a87c8..ff09080e2a8 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/insert-an-element-into-a-max-heap.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/insert-an-element-into-a-max-heap.md
@@ -1,6 +1,6 @@
 ---
 id: 587d825a367417b2b2512c8a
-title: Insert an Element into a Max Heap
+title: Inserisci un elemento in un max heap
 challengeType: 1
 forumTopicId: 301703
 dashedName: insert-an-element-into-a-max-heap
@@ -8,47 +8,47 @@ dashedName: insert-an-element-into-a-max-heap
 
 # --description--
 
-Now we will move on to another tree data structure, the binary heap. A binary heap is a partially ordered binary tree which satisfies the heap property. The heap property specifies a relationship between parent and child nodes. You may have a max heap, in which all parent nodes are greater than or equal to their child nodes, or a min heap, in which the reverse is true. Binary heaps are also complete binary trees. This means that all levels of the tree are fully filled and if the last level is partially filled it is filled from left to right.
+Ora passeremo ad un'altra struttura di dati ad albero, l'heap binario. Un heap binario è un albero binario parzialmente ordinato che soddisfa la proprietà heap. La proprietà heap specifica una relazione tra nodi genitore e figlio. Potresti avere un max heap, in cui tutti i nodi genitori sono maggiori o uguali ai loro nodi figli, o un min heap, in cui il contrario è vero. Gli heap binari sono anche alberi binari completi. Questo significa che tutti i livelli dell'ablero sono completamente pieni e se l'ultimo livello è completo solo parzialmente è riempido da sinistra a destra.
 
-While binary heaps may be implemented as tree structures with nodes that contain left and right references, the partial ordering according to the heap property allows us to represent the heap with an array. The parent-children relationship is what we're interested in and with simple arithmetic we can compute the children of any parent and the parent of any child node.
+Anche se gli heap binari possono essere implementati come strutture ad albero con nodi che contengono riferimenti di sinistra e destra, l'ordine parziale in base alla proprietà heap ci permette di rappresentare l'heap con un array. Il rapporto genitore-figlio è quello a cui siamo interessati e con semplice aritmetica possiamo calcolare i figli di qualsiasi genitore e genitore di qualsiasi nodo figlio.
 
-For instance, consider this array representation of a binary min heap:
+Per esempio, considera questa rappresentazione array di un min heap binario:
 
 ```js
 [ 6, 22, 30, 37, 63, 48, 42, 76 ]
 ```
 
-The root node is the first element, `6`. Its children are `22` and `30`. If we look at the relationship between the array indices of these values, for index `i` the children are `2 * i + 1` and `2 * i + 2`. Similarly, the element at index `0` is the parent of these two children at indices `1` and `2`. More generally, we can find the parent of a node at any index with the following: `Math.floor((i - 1) / 2)`. These patterns will hold true as the binary tree grows to any size. Finally, we can make a slight adjustment to make this arithmetic even easier by skipping the first element in the array. Doing this creates the following relationship for any element at a given index `i`:
+Il nodo radice è il primo elemento, `6`. I suoi figli sono `22` e `30`. Se consideriamo il rapporto tra gli indici di questi valori, per indice `i` i figli sono `2 * i + 1` e `2 * i + 2`. Analogamente, l'elemento all'indice `0` è il genitore di questi due figli agli indici `1` e `2`. Più in generale, possiamo trovare il genitore di un nodo in qualsiasi indice con il seguente: `Math.floor((i - 1) / 2)`. Questi pattern resteranno veri come l'albero cresce ad ogni dimensione. Infine, possiamo fare alcuni piccoli aggiustamenti per fare questa aritmetica ancora più semplice saltando il primo elemento dell'array. Facendo ciò si crea la seguente relazione per ogni elemento ad un dato indice `i`:
 
-Example array representation:
+Esempio di rappresentazione come array:
 
 ```js
 [ null, 6, 22, 30, 37, 63, 48, 42, 76 ]
 ```
 
-An element's left child: `i * 2`
+Il figlio sinistro di un elemento: `i * 2`
 
-An element's right child: `i * 2 + 1`
+Il figlio destro di un elemento: `i * 2 + 1`
 
-An element's parent: `Math.floor(i / 2)`
+Il genitore di un elemento: `Math.floor(i / 2)`
 
-Once you wrap your head around the math, using an array representation is very useful because node locations can be quickly determined with this arithmetic and memory usage is diminished because you don't need to maintain references to child nodes.
+Una volta che prendi familiarità con la matematica, usare una rappresentazione ad array è molto utile perché la posizione dei nodi può essere determinata con questa artimetica e l'uso della memoria è diminuito perché non devi mantenere i riferimenti ai nodi figli.
 
 # --instructions--
 
-Instructions: Here we will create a max heap. Start by just creating an `insert` method which adds elements to our heap. During insertion, it is important to always maintain the heap property. For a max heap this means the root element should always have the greatest value in the tree and all parent nodes should be greater than their children. For an array implementation of a heap, this is typically accomplished in three steps:
+Istruzioni: qui creeremo un max heap. Inizia creando semplicemente un metodo `insert` che aggiunge elementi al nostro heap. Durante l'inserzione, è importante mantenere sempre la proprietà heap. Per un max heap questo significa che l'elemento root deve sempre avere il valore maggiore nell'albero e tutti i nodi genitori devono essere più grandi dei loro figli. Per una rappresentazione ad array di un heap questo è tipicamente fatto in tre step:
 
 <ol>
-  <li>Add the new element to the end of the array.</li>
-  <li>If the element is larger than its parent, switch them.</li>
-  <li>Continue switching until the new element is either smaller than its parent or you reach the root of the tree.</li>
+  <li>Aggiungi il nuovo elemento alla fine dell'array.</li>
+  <li>Se l'elemento è maggiore del suo genitore, scambiali.</li>
+  <li>Continua a scambiare finché il nuovo elemento è più piccolo del genitore o raggiungi l'elemento root.</li>
 </ol>
 
-Finally, add a `print` method which returns an array of all the items that have been added to the heap.
+Alla fine, aggiungi un metodo `print` che restituire un array di tutti gli elementi che sono stati aggiunti al heap.
 
 # --hints--
 
-The MaxHeap data structure should exist.
+La struttura dati MaxHeap dovrebbe esistere.
 
 ```js
 assert(
@@ -62,7 +62,7 @@ assert(
 );
 ```
 
-MaxHeap should have a method called insert.
+MaxHeap dovrebbe avere un metodo chiamato insert.
 
 ```js
 assert(
@@ -78,7 +78,7 @@ assert(
 );
 ```
 
-MaxHeap should have a method called print.
+MaxHeap dovrebbe avere un metodo chiamato print.
 
 ```js
 assert(
@@ -94,7 +94,7 @@ assert(
 );
 ```
 
-The insert method should add elements according to the max heap property.
+Il metodo insert dovrebbe aggiungere elementi rispettando la proprietà max heap.
 
 ```js
 assert(
@@ -133,20 +133,28 @@ var MaxHeap = function() {
 ```js
 var MaxHeap = function() {
     // Only change code below this line
-    this.heap = [null];
-    this.insert = (ele) => {
-        var index = this.heap.length;
-        var arr = [...this.heap];
-        arr.push(ele);
-        while (ele > arr[Math.floor(index / 2)] && index > 1) {
-            arr[index] = arr[Math.floor(index / 2)];
-            arr[Math.floor(index / 2)] = ele;
-            index = arr[Math.floor(index / 2)];
-        }
-        this.heap = arr;
+    this.heap = [];
+    this.parent = index => {
+      return Math.floor((index - 1) / 2);
+    }
+    this.insert = element => {
+      this.heap.push(element);
+      this.heapifyUp(this.heap.length - 1);
+    }
+    this.heapifyUp = index => {
+      let currentIndex = index,
+      parentIndex = this.parent(currentIndex);
+      while (currentIndex > 0 && this.heap[currentIndex] > this.heap[parentIndex]) {
+        this.swap(currentIndex, parentIndex);
+        currentIndex = parentIndex;
+        parentIndex = this.parent(parentIndex);
+      }
+    }
+    this.swap = (index1, index2) => {
+      [this.heap[index1], this.heap[index2]] = [this.heap[index2], this.heap[index1]];
     }
     this.print = () => {
-        return this.heap.slice(1);
+      return this.heap;
     }
     // Only change code above this line
 };
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/invert-a-binary-tree.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/invert-a-binary-tree.md
index 8be38b0d5d8..aa8f95560e1 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/invert-a-binary-tree.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/invert-a-binary-tree.md
@@ -1,6 +1,6 @@
 ---
 id: 587d8259367417b2b2512c83
-title: Invert a Binary Tree
+title: Invertire un albero binario
 challengeType: 1
 forumTopicId: 301704
 dashedName: invert-a-binary-tree
@@ -8,11 +8,11 @@ dashedName: invert-a-binary-tree
 
 # --description--
 
-Here will we create a function to invert a binary tree. Given a binary tree, we want to produce a new tree that is equivalently the mirror image of this tree. Running an inorder traversal on an inverted tree will explore the nodes in reverse order when compared to the inorder traversal of the original tree. Write a method to do this called `invert` on our binary tree. Calling this method should invert the current tree structure. Ideally, we would like to do this in-place in linear time. That is, we only visit each node once and we modify the existing tree structure as we go, without using any additional memory. Good luck!
+Qui creeremo una funzione per invertire un albero binario. Dato un albero binario, vogliamo produrre un nuovo albero che sia equivalente all'immagine speculare di questo albero. Eseguire un traversamento inorder su un albero invertito esplora i nodi in ordine inverso rispetto a un traversamento inorder sull'albero originale. Scrivi un metodo per farlo, chiamato `invert` sul nostro albero binario. Chiamare questo metodo dovrebbe invertire la struttura attuale dell'albero. Idealmente, vorremmo fare questo "in-place" (NdT: lavorando sull'array originale, senza crearne una copia) e in tempo lineare. Cioè, visitiamo ogni nodo solo una volta e modifichiamo la struttura di albero esistente mentre procediamo, senza usare memoria aggiuntiva. Buona fortuna!
 
 # --hints--
 
-The `BinarySearchTree` data structure should exist.
+La struttura di dati `BinarySearchTree` dovrebbe esistere.
 
 ```js
 assert(
@@ -26,7 +26,7 @@ assert(
 );
 ```
 
-The binary search tree should have a method called `invert`.
+L'albero binario di ricerca dovrebbe avere un metodo chiamato `invert`.
 
 ```js
 assert(
@@ -42,7 +42,7 @@ assert(
 );
 ```
 
-The `invert` method should correctly invert the tree structure.
+Il metodo `invert` dovrebbe invertire correttamente la struttura dell'albero.
 
 ```js
 assert(
@@ -70,7 +70,7 @@ assert(
 );
 ```
 
-Inverting an empty tree should return `null`.
+Invertire un albero vuoto dovrebbe restituire `null`.
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/remove-an-element-from-a-max-heap.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/remove-an-element-from-a-max-heap.md
index 858073f2112..cff5e8f7a85 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/remove-an-element-from-a-max-heap.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/remove-an-element-from-a-max-heap.md
@@ -1,6 +1,6 @@
 ---
 id: 587d825b367417b2b2512c8b
-title: Remove an Element from a Max Heap
+title: Rimuovere un elemento da una max-heap
 challengeType: 1
 forumTopicId: 301710
 dashedName: remove-an-element-from-a-max-heap
@@ -8,21 +8,21 @@ dashedName: remove-an-element-from-a-max-heap
 
 # --description--
 
-Now that we can add elements to our heap let's see how we can remove elements. Removing and inserting elements both require similar logic. In a max heap you will usually want to remove the greatest value, so this involves simply extracting it from the root of our tree. This will break the heap property of our tree, so we must reestablish it in some way. Typically, for a max heap this is done in the following way:
+Ora che possiamo aggiungere elementi al nostro heap vediamo come possiamo rimuovere gli elementi. La rimozione e l'inserimento di elementi richiedono una logica simile. In un max-heap di solito si vuole rimuovere il valore maggiore, quindi questo implica semplicemente estrarlo dalla radice del nostro albero. Questo negherà la proprietà heap del nostro albero, quindi dovremo ristabilirla in qualche modo. Tipicamente, per un max-heap questo viene fatto nel modo seguente:
 
 <ol>
-  <li>Move the last element in the heap into the root position.</li>
-  <li>If either child of the root is greater than it, swap the root with the child of greater value.</li>
-  <li>Continue swapping until the parent is greater than both children or you reach the last level in the tree.</li>
+  <li>Sposta l'ultimo elemento nell'heap alla posizione root.</li>
+  <li>Se uno dei figli della radice è maggiore di essa, scambiare la radice con il figlio di valore maggiore.</li>
+  <li>Continuare a scambiare fino a quando il genitore è maggiore di entrambi i figli o si raggiunge l'ultimo livello nell'albero.</li>
 </ol>
 
 # --instructions--
 
-Instructions: Add a method to our max heap called `remove`. This method should return the greatest value that has been added to our max heap and remove it from the heap. It should also reorder the heap so the heap property is maintained. After removing an element, the next greatest element remaining in the heap should become the root.
+Istruzioni: Aggiungere un metodo al nostro max-heap chiamato `remove`. Questo metodo dovrebbe restituire il massimo valore che è stato aggiunto al nostro max heap e rimuoverlo dal mucchio. Dovrebbe anche riordinare il mucchio in modo che la proprietà heap sia mantenuta. Dopo aver rimosso un elemento, il prossimo elemento più grande che rimane nel heap dovrebbe diventare la radice.
 
 # --hints--
 
-The MaxHeap data structure should exist.
+La struttura dati MaxHeap dovrebbe esistere.
 
 ```js
 assert(
@@ -36,7 +36,7 @@ assert(
 );
 ```
 
-MaxHeap should have a method called print.
+MaxHeap dovrebbe avere un metodo chiamato print.
 
 ```js
 assert(
@@ -52,7 +52,7 @@ assert(
 );
 ```
 
-MaxHeap should have a method called insert.
+MaxHeap dovrebbe avere un metodo chiamato insert.
 
 ```js
 assert(
@@ -68,7 +68,7 @@ assert(
 );
 ```
 
-MaxHeap should have a method called remove.
+MaxHeap dovrebbe avere un metodo chiamato remove.
 
 ```js
 assert(
@@ -84,7 +84,7 @@ assert(
 );
 ```
 
-The remove method should remove the greatest element from the max heap while maintaining the max heap property.
+Il metodo remove dovrebbe rimuovere l'elemento più grande dal max heap mantenendo la proprietà max heap.
 
 ```js
 assert(
@@ -114,21 +114,29 @@ assert(
 ## --seed-contents--
 
 ```js
-var MaxHeap = function() {
-  this.heap = [null];
-  this.insert = (ele) => {
-    var index = this.heap.length;
-    var arr = [...this.heap];
-    arr.push(ele);
-    while (ele > arr[Math.floor(index / 2)] && index > 1) {
-      arr[index] = arr[Math.floor(index / 2)];
-      arr[Math.floor(index / 2)] = ele;
-      index = arr[Math.floor(index / 2)];
+var MaxHeap = function () {
+  this.heap = [];
+  this.parent = index => {
+    return Math.floor((index - 1) / 2);
+  }
+  this.insert = element => {
+    this.heap.push(element);
+    this.heapifyUp(this.heap.length - 1);
+  }
+  this.heapifyUp = index => {
+    let currentIndex = index,
+    parentIndex = this.parent(currentIndex);
+    while (currentIndex > 0 && this.heap[currentIndex] > this.heap[parentIndex]) {
+      this.swap(currentIndex, parentIndex);
+      currentIndex = parentIndex;
+      parentIndex = this.parent(parentIndex);
     }
-    this.heap = arr;
+  }
+  this.swap = (index1, index2) => {
+    [this.heap[index1], this.heap[index2]] = [this.heap[index2], this.heap[index1]];
   }
   this.print = () => {
-    return this.heap.slice(1);
+    return this.heap;
   }
   // Only change code below this line
 
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/remove-elements-from-a-linked-list-by-index.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/remove-elements-from-a-linked-list-by-index.md
index 9a8e59f77fc..7c17dd9917c 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/remove-elements-from-a-linked-list-by-index.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/remove-elements-from-a-linked-list-by-index.md
@@ -1,6 +1,6 @@
 ---
 id: 587d8251367417b2b2512c65
-title: Remove Elements from a Linked List by Index
+title: Rimuovere gli elementi da una lista concatenata usando l'indice
 challengeType: 1
 forumTopicId: 301711
 dashedName: remove-elements-from-a-linked-list-by-index
@@ -8,23 +8,23 @@ dashedName: remove-elements-from-a-linked-list-by-index
 
 # --description--
 
-Before we move on to another data structure, let's get a couple of last bits of practice with linked lists.
+Prima di passare ad un'altra struttura di dati, otteniamo un altro po' di pratica con liste concatenate.
 
-Let's write a `removeAt` method that removes the `element` at a given `index`. The method should be called `removeAt(index)`. To remove an `element` at a certain `index`, we'll need to keep a running count of each node as we move along the linked list.
+Scriviamo un metodo `removeAt` che rimuove l'elemento `element` in un dato `index`. Il metodo dovrebbe essere chiamato `removeAt(index)`. Per rimuovere un `element` a un certo `index`, avremo bisogno di mantenere un conteggio in esecuzione di ogni nodo mentre ci muoviamo lungo la lista concatenata.
 
-A common technique used to iterate through the elements of a linked list involves a <dfn>'runner'</dfn>, or sentinel, that 'points' at the nodes that your code is comparing. In our case, starting at the `head` of our list, we start with a `currentIndex` variable that starts at `0`. The `currentIndex` should increment by one for each node we pass.
+Una tecnica comune utilizzata per iterare attraverso gli elementi di una lista concatenata comporta un <dfn>'runner'</dfn>, o sentinella, che 'punti' ai nodi che il tuo codice sta confrontando. Nel nostro caso, a partire dalla `head` della nostra lista, iniziamo con una variabile `currentIndex` che inizia da `0`. Il `currentIndex` dovrebbe aumentare di uno per ogni nodo che passiamo.
 
-Just like our `remove(element)` method, which [we covered in a previous lesson](/learn/coding-interview-prep/data-structures/remove-elements-from-a-linked-list), we need to be careful not to orphan the rest of our list when we remove the node in our `removeAt(index)` method. We keep our nodes contiguous by making sure that the node that has reference to the removed node has a reference to the next node.
+Proprio come il nostro metodo `remove(element)`, che [abbiamo coperto in una lezione precedente](/italian/learn/coding-interview-prep/data-structures/remove-elements-from-a-linked-list), dobbiamo stare attenti a non rendere orfano il resto della nostra lista quando rimuoviamo il nodo nel nostro metodo `removeAt(index)`. Manteniamo i nostri nodi contigui assicurandoci che il nodo che fa riferimento al nodo rimosso abbia un riferimento al nodo successivo.
 
 # --instructions--
 
-Write a `removeAt(index)` method that removes and returns a node at a given `index`. The method should return `null` if the given `index` is either negative, or greater than or equal to the `length` of the linked list.
+Scrivi un metodo `removeAt(index)` che rimuove e restituisce un nodo a un certo `index`. Il metodo dovrebbe restituire `null` se l'`index` dato è o negativo, o superiore o uguale alla `length` della lista concatenata.
 
-**Note:** Remember to keep count of the `currentIndex`.
+**Nota:** Ricordati di mantenere il conteggio del `currentIndex`.
 
 # --hints--
 
-Your `LinkedList` class should have a `removeAt` method.
+La tua classe `LinkedList` dovrebbe avere un metodo `removeAt`.
 
 ```js
 assert(
@@ -35,7 +35,7 @@ assert(
 );
 ```
 
-Your `removeAt` method should reduce the `length` of the linked list by one.
+Il tuo metodo `removeAt` dovrebbe ridurre `length` della lista collegata di uno.
 
 ```js
 assert(
@@ -50,7 +50,7 @@ assert(
 );
 ```
 
-Your `removeAt` method should remove the element at the specified index from the linked list.
+Il tuo metodo `removeAt` dovrebbe rimuovere l'elemento all'indice specificato dalla lista collegata.
 
 ```js
 assert(
@@ -69,7 +69,7 @@ assert(
 );
 ```
 
-When only one element is present in the linked list, your `removeAt` method should remove and return the element at specified index, and reduce the length of the linked list.
+Quando un solo elemento è presente nell'elenco collegato, il tuo metodo `removeAt` dovrebbe rimuovere e restituire l'elemento all'indice specificato e ridurre la lunghezza della lista concatenata.
 
 ```js
 assert(
@@ -82,7 +82,7 @@ assert(
 );
 ```
 
-Your `removeAt` method should return the element of the removed node.
+Il metodo `removeAt` dovrebbe restituire l'elemento del nodo rimosso.
 
 ```js
 assert(
@@ -96,7 +96,7 @@ assert(
 );
 ```
 
-Your `removeAt` method should return `null` and the linked list should not change if the given index is less than `0`.
+Il tuo metodo `removeAt` dovrebbe restituire `null` e la lista concatenata non dovrebbe cambiare se l'indice dato è inferiore a `0`.
 
 ```js
 assert(
@@ -115,7 +115,7 @@ assert(
 );
 ```
 
-Your `removeAt` method should return `null` and the linked list should not change if the given index is greater than or equal to the `length` of the list.
+Il tuo metodo `removeAt` dovrebbe restituire `null` e la lista concatenata non dovrebbe cambiare se l'indice dato è maggiore o uguale a `length` dell'elenco.
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/remove-elements-from-a-linked-list.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/remove-elements-from-a-linked-list.md
index a202036ff08..af03773649f 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/remove-elements-from-a-linked-list.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/remove-elements-from-a-linked-list.md
@@ -1,6 +1,6 @@
 ---
 id: 587d8251367417b2b2512c63
-title: Remove Elements from a Linked List
+title: Rimuovi gli elementi da una lista concatenata
 challengeType: 1
 forumTopicId: 301712
 dashedName: remove-elements-from-a-linked-list
@@ -8,23 +8,23 @@ dashedName: remove-elements-from-a-linked-list
 
 # --description--
 
-The next important method that any implementation of a linked list will need is a `remove` method. This method should take the element we want to remove as an argument, and then search the list to find and remove the node that contains that element.
+Il metodo successivo importante che ogni implementazione di una lista concatenata avrà bisogno è un metodo `remove`. Questo metodo dovrebbe prendere l'elemento che vogliamo rimuovere come un argomento, e quindi cercare l'elenco per trovare e rimuovere il nodo che contiene quell'elemento.
 
-Whenever we remove a node from a linked list, it's important that we don't accidentally orphan the rest of the list in doing so. Recall that every node's `next` property points to the node that follows it in the list. If we're removing the middle element, say, we'll want to make sure that we have a connection from that element's previous node's `next` property to the middle element's `next` property (which is the next node in the list!)
+Ogni volta che rimuovi un nodo da una lista collegata, è importante che non orfani accidentalmente il resto della lista nel farlo. Ricorda che la proprietà `next` di ogni nodo punta al nodo che lo segue nella lista. Se stiamo rimuovendo l'elemento di mezzo, vogliamo fare in modo che c'è una connessione tra la proprietà `next` dell'elemento precedente e la proprietà `next` dell'elemento di mezzo (che è il nodo seguente nella lista!)
 
-This might sound really confusing, so let's return to the conga line example so we have a good conceptual model. Picture yourself in a conga line, and the person directly in front of you leaves the line. The person who just left the line no longer has her hands on anyone in line--and you no longer have your hands on the person that left. You step forward and put your hands on next person you see.
+Questo può essere davvero confusionario, quindi ritornaimo all'esempio del trenino così abbiamo un buon modello concettuale. Immaginati in un trenino, e la persona direttamente davanti a te lascia la fila. La persona che ha appena lasciato la fina non ha più le mani sulle spalle di nessuno, e tu non hai più le mani sulle spalle della persona che se ne è andata. Fai un passo avanti e metti le mani sulle spalle della persona davanti a te.
 
-If the element we wish to remove is the `head` element, we reassign the `head` to the second node of the linked list.
+Se l'elemento che vogliamo rimuovere è l'elemento `head`, assegniamo `head` al secondo nodo della lista concatenata.
 
 # --instructions--
 
-Write a `remove` method that takes an element and removes it from the linked list.
+Scrivi un metodo `remove` che prende un elemento e lo rimuove dalla lista collegata.
 
-**Note:** The `length` of the list should decrease by one every time an element is removed from the linked list.
+**Nota:** La lunghezza della lista dovrebbe diminuire di uno ogni volta che un elemento viene rimosso dalla lista collegata.
 
 # --hints--
 
-Your `LinkedList` class should have a `remove` method.
+La tua classe `LinkedList` dovrebbe avere un metodo `remove`.
 
 ```js
 assert(
@@ -35,7 +35,7 @@ assert(
 );
 ```
 
-Your `remove` method should reassign `head` to the second node when the first node is removed.
+Il tuo metodo `remove` dovrebbe riassegnare `head` al secondo nodo quando il primo nodo è rimosso.
 
 ```js
 assert(
@@ -49,7 +49,7 @@ assert(
 );
 ```
 
-Your `remove` method should decrease the `length` of the linked list by one for every node removed.
+Il tuo metodo `remove` dovrebbe diminuire `length` della lista concatenata di uno per ogni nodo rimosso.
 
 ```js
 assert(
@@ -65,7 +65,7 @@ assert(
 );
 ```
 
-Your `remove` method should reassign the reference of the previous node of the removed node to the removed node's `next` reference.
+Il tuo metodo `remove` dovrebbe riassegnara il riferimento del nodo precedente del nodo rimosso al rifermento `next` del nodo rimosso.
 
 ```js
 assert(
@@ -81,7 +81,7 @@ assert(
 );
 ```
 
-Your `remove` method should not change the linked list if the element does not exist in the linked list.
+Il tuo metodo `remove` non dovrebbe cambiare la lista concatenata se l'elemento non esiste nella lista concatenata.
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/search-within-a-linked-list.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/search-within-a-linked-list.md
index 03361689fef..e17f29b048d 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/search-within-a-linked-list.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/search-within-a-linked-list.md
@@ -1,6 +1,6 @@
 ---
 id: 587d8251367417b2b2512c64
-title: Search within a Linked List
+title: Cercare in una lista concatenata
 challengeType: 1
 forumTopicId: 301715
 dashedName: search-within-a-linked-list
@@ -8,19 +8,19 @@ dashedName: search-within-a-linked-list
 
 # --description--
 
-Let's add a few more useful methods to our linked list class. Wouldn't it be useful if we could tell if our list was empty or not, as with our `Stack` and `Queue` classes?
+Aggiungiamo alcuni altri metodi utili alla nostra classe di lista concatenata. Non sarebbe utile se potessimo dire se la nostra lista sia vuota o no, come con le nostre classi `Stack` e `Queue`?
 
-We should also be able to find specific elements in our linked list. Traversing through data structures is something you'll want to get a lot of practice with! Let's create an `indexOf` method that takes an `element` as an argument, and returns that element's `index` in the linked list. If the element is not found in the linked list, return `-1`.
+Dovremmo anche essere in grado di trovare elementi specifici nella nostra lista concatenata. Traversare strutture di dati è qualcosa con cui vorrai fare un sacco di pratica! Creiamo un metodo `indexOf` che prende `element` coem argomento, e restituisce l'`index` di quell'elemento nella lista concatenata. Se l'elemento non è trovato nella lista collegata, restituisci `-1`.
 
-Let's also implement a method that does the opposite: an `elementAt` method that takes an `index` as an argument and returns the `element` at the given `index`. If no `element` is found, return `undefined`.
+Implementiamo pure un metodo che fa l'opposto: un metodo `elementAt` che accetta un `index` come argomento e restituisce `element` al dato `index`. Se nessun elemento `element` è trovato, restituisci `undefined`.
 
 # --instructions--
 
-Write an `isEmpty` method that checks if the linked list is empty, an `indexOf` method that returns the `index` of a given element, and an `elementAt` that returns an `element` at a given `index.`
+Scrivi un metodo `isEmpty` che verifica se la lista concatenata è vuota, un metodo `indexOf` che restituisce l'`index` di un dato elemento, e un metodo `elementAt` che restituisce l'`element` al dato `index.`
 
 # --hints--
 
-Your `LinkedList` class should have an `isEmpty` method.
+La tua classe `LinkedList` dovrebbe avere un metodo `isEmpty`.
 
 ```js
 assert(
@@ -31,7 +31,7 @@ assert(
 );
 ```
 
-Your `isEmpty` method should return `false` when there is at least one element in linked list.
+Il tuo metodo `isEmpty` dovrebbe restituire `false` quando c'è almeno un elemento nella lista concatenata.
 
 ```js
 assert(
@@ -45,7 +45,7 @@ assert(
 );
 ```
 
-Your `isEmpty` method should return `true` when there are no elements in linked list.
+Il tuo metodo `isEmpty` dovrebbe restituire `true` quando non ci sono elementi nella lista concatenata.
 
 ```js
 assert(
@@ -56,7 +56,7 @@ assert(
 );
 ```
 
-Your `LinkedList` class should have an `indexOf` method.
+La tua classe `LinkedList` dovrebbe avere un metodo `indexOf`.
 
 ```js
 assert(
@@ -67,7 +67,7 @@ assert(
 );
 ```
 
-Your `indexOf` method should return the index of a given element found in linked list.
+Il tuo metodo `indexOf` dovrebbe restituire l'indice di un dato elemento trovato nella lista concatenata.
 
 ```js
 assert(
@@ -81,7 +81,7 @@ assert(
 );
 ```
 
-Your `indexOf` method should return `-1` if the given element is not found in linked list
+Il tuo metodo `indexOf` dovrebbe restituire `-1` se l'elemento dato non è trovato nella lista concatenata
 
 ```js
 assert(
@@ -95,7 +95,7 @@ assert(
 );
 ```
 
-Your `LinkedList` class should have an `elementAt` method.
+La tua classe `LinkedList` dovrebbe avere un metodo `elementAt`.
 
 ```js
 assert(
@@ -106,7 +106,7 @@ assert(
 );
 ```
 
-Your `elementAt` method should return the element found at a given index in linked list.
+Il tuo metodo `elementAt` dovrebbe restituire l'elemento trovato in un dato indice nella lista concatenata.
 
 ```js
 assert(
@@ -120,7 +120,7 @@ assert(
 );
 ```
 
-Your `elementAt` method should return `undefined` if the given element is not found at a given index in linked list.
+Il tuo `elementAt` metodo dovrebbe restituire `undefined` se l'elemento dato non è trovato in un dato indice nella lista concatenata.
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/typed-arrays.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/typed-arrays.md
index b992af729a4..23a3b80b1d9 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/typed-arrays.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/typed-arrays.md
@@ -1,6 +1,6 @@
 ---
 id: 587d8253367417b2b2512c6a
-title: Typed Arrays
+title: Array Digitati
 challengeType: 1
 forumTopicId: 301716
 dashedName: typed-arrays
@@ -8,21 +8,21 @@ dashedName: typed-arrays
 
 # --description--
 
-Arrays are JavaScript objects that can hold a lot of different elements.
+Gli array sono oggetti JavaScript che possono contenere molti elementi diversi.
 
 ```js
 var complexArr = [1, 5, "2", "Word", {"name": "James"}];
 ```
 
-Basically what happens in the background is that your browser will automatically give the right amount of memory space for that array. It will also change as needed if you add or remove data.
+Fondamentalmente ciò che accade in background è che il browser darà automaticamente la giusta quantità di spazio di memoria per quell'array. Cambierà anche al bisogno se si aggiungono o rimuovono i dati.
 
-However, in the world of high performance and different element types, sometimes you need to be more specific on how much memory is given to an array.
+Tuttavia, nel mondo delle alte prestazioni e dei diversi tipi di elementi, a volte è necessario essere più specifici su quanto memoria viene dato a un array.
 
-<dfn>Typed arrays</dfn> are the answer to this problem. You are now able to say how much memory you want to give an array. Below is a basic overview of the different types of arrays available and the size in bytes for each element in that array.
+<dfn>Gli array digitati</dfn> sono la risposta a questo problema. Ora sei in grado di dire quanta memoria vuoi allocare per un dato array. Di seguito una panoramica di base dei diversi tipi di array disponibili e la dimensione in byte per ogni elemento in quell'array.
 
-<table class='table table-striped'><tbody><tr><th>Type</th><th>Each element size in bytes</th></tr><tr><td><code>Int8Array</code></td><td>1</td></tr><tr><td><code>Uint8Array</code></td><td>1</td></tr><tr><td><code>Uint8ClampedArray</code></td><td>1</td></tr><tr><td><code>Int16Array</code></td><td>2</td></tr><tr><td><code>Uint16Array</code></td><td>2</td></tr><tr><td><code>Int32Array</code></td><td>4</td></tr><tr><td><code>Uint32Array</code></td><td>4</td></tr><tr><td><code>Float32Array</code></td><td>4</td></tr><tr><td><code>Float64Array</code></td><td>8</td></tr></tbody></table>
+<table class='table table-striped'><tbody><tr><th>Tipo</th><th>La dimensione di ogni elemento in byte</th></tr><tr><td><code>Int8Array</code></td><td>1</td></tr><tr><td><code>Uint8Array</code></td><td>1</td></tr><tr><td><code>Uint8ClampedArray</code></td><td>1</td></tr><tr><td><code>Int16Array</code></td><td>2</td></tr><tr><td><code>Uint16Array</code></td><td>2</td></tr><tr><td><code>Int32Array</code></td><td>4</td></tr><tr><td><code>Uint32Array</code></td><td>4</td></tr><tr><td><code>Float32Array</code></td><td>4</td></tr><tr><td><code>Float64Array</code></td><td>8</td></tr></tbody></table>
 
-There are two ways in creating these kind of arrays. One way is to create it directly. Below is how to create a 3 length `Int16Array`.
+Ci sono due modi per creare questi tipi di array. Un modo è di crearli direttamente. Di seguito è riportato come creare un `Int16Array` di lunghezza 3.
 
 ```js
 var i8 = new Int16Array(3);
@@ -30,8 +30,8 @@ console.log(i8);
 // Returns [0, 0, 0]
 ```
 
-You can also create a <dfn>buffer</dfn> to assign how much data (in bytes) you want the array to take up. **Note**  
-To create typed arrays using buffers, you need to assign the number of bytes to be a multiple of the bytes listed above.
+Puoi ache creare un <dfn>buffer</dfn> per assegnare quanti dati (in byte) vuoi che il tuo array occupi. **Nota**  
+Per creare array digitat usando buffer, devi assegnare il numero di byte come multiple dei byte elencati precedentemente.
 
 ```js
 // Create same Int16Array array differently
@@ -43,35 +43,35 @@ i8View.byteLength; // Returns 6
 console.log(i8View); // Returns [0, 0, 0]
 ```
 
-<dfn>Buffers</dfn> are general purpose objects that just carry data. You cannot access them normally. To access them, you need to first create a <dfn>view</dfn>.
+I <dfn>buffer</dfn> sono oggetti a scopo generico che contengono solo dati. Non puoi accedervi normalmente. Per accederci devi prima creare una <dfn>view</dfn>.
 
 ```js
 i8View[0] = 42;
 console.log(i8View); // Returns [42, 0, 0]
 ```
 
-**Note**  
-Typed arrays do not have some of the methods traditional arrays have such as `.pop()` or `.push()`. Typed arrays also fail `Array.isArray()` that checks if something is an array. Although simpler, this can be an advantage for less-sophisticated JavaScript engines to implement them.
+**Nota**  
+Array digitati non hanno alcuni dei metodi degli array tradizioni come `.pop()` o `.push()`. Gli array digitati fanno restituire false ad `Array.isArray()` che controlla se qualcosa è un array. Anche se più semplice, questo può essere un vantaggio per i motori JavaScript meno sofisticati per implementarli.
 
 # --instructions--
 
-First create a `buffer` that is 64-bytes. Then create a `Int32Array` typed array with a view of it called `i32View`.
+Come prima cosa crea un `buffer` che è 64 byte. Quindi crea un array digitato `Int32Array` con una view chiamata `i32View`.
 
 # --hints--
 
-Your `buffer` should be 64 bytes large.
+Il tuo `buffer` dovrebbe occupare 64 byte.
 
 ```js
 assert(buffer.byteLength === 64);
 ```
 
-Your `i32View` view of your buffer should be 64 bytes large.
+La tua view `i32View` del tuo buffer dovrebbe occupare 64 byte.
 
 ```js
 assert(i32View.byteLength === 64);
 ```
 
-Your `i32View` view of your buffer should be 16 elements long.
+La tua view `i32View` del tuo buffer dovrebbe avere 16 elementi.
 
 ```js
 assert(i32View.length === 16);
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/use-.has-and-.size-on-an-es6-set.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/use-.has-and-.size-on-an-es6-set.md
index 55d4ac67de8..de0ebdcc956 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/use-.has-and-.size-on-an-es6-set.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/use-.has-and-.size-on-an-es6-set.md
@@ -1,6 +1,6 @@
 ---
 id: 587d8255367417b2b2512c72
-title: Use .has and .size on an ES6 Set
+title: Usare .has e .size su un set ES6
 challengeType: 1
 forumTopicId: 301717
 dashedName: use--has-and--size-on-an-es6-set
@@ -8,21 +8,21 @@ dashedName: use--has-and--size-on-an-es6-set
 
 # --description--
 
-Let's look at the .has and .size methods available on the ES6 Set object.
+Diamo un'occhiata ai metodi .has e .size disponibili sull'oggetto Set ES6.
 
-First, create an ES6 Set
+Per prima cosa, crea un Set ES6
 
 ```js
 var set = new Set([1,2,3]);
 ```
 
-The .has method will check if the value is contained within the set.
+Il metodo .has controllerà se il valore è contenuto all'interno del set.
 
 ```js
 var hasTwo = set.has(2);
 ```
 
-The .size method will return an integer representing the size of the Set
+Il metodo .size restituirà un numero intero rappresentante la dimensione del Set
 
 ```js
 var howBig = set.size;
@@ -30,11 +30,11 @@ var howBig = set.size;
 
 # --instructions--
 
-In this exercise we will pass an array and a value to the checkSet() function. Your function should create an ES6 set from the array argument. Find if the set contains the value argument. Find the size of the set. And return those two values in an array.
+In questo esercizio passeremo un array e un valore alla funzione checkSet(). La tua funzione dovrebbe creare un set ES& dall'argomento array. Scopri se il set contiene il valore argomento. Trova la dimensione del set. E restituire questi due valori in un array.
 
 # --hints--
 
-`checkSet([4, 5, 6], 3)` should return [ false, 3 ]
+`checkSet([4, 5, 6], 3)` dovrebbe restituire [ false, 3 ]
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/use-breadth-first-search-in-a-binary-search-tree.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/use-breadth-first-search-in-a-binary-search-tree.md
index b02f10043d3..74b6bdd7ee1 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/use-breadth-first-search-in-a-binary-search-tree.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/use-breadth-first-search-in-a-binary-search-tree.md
@@ -1,6 +1,6 @@
 ---
 id: 587d8258367417b2b2512c7f
-title: Use Breadth First Search in a Binary Search Tree
+title: Una la ricerca in ampiezza nella ricerca binaria in un albero
 challengeType: 1
 forumTopicId: 301718
 dashedName: use-breadth-first-search-in-a-binary-search-tree
@@ -8,17 +8,17 @@ dashedName: use-breadth-first-search-in-a-binary-search-tree
 
 # --description--
 
-Here we will introduce another tree traversal method: breadth-first search. In contrast to the depth-first search methods from the last challenge, breadth-first search explores all the nodes in a given level within a tree before continuing on to the next level. Typically, queues are utilized as helper data structures in the design of breadth-first search algorithms.
+Qui introdurremo un altro metodo traversale di albero: la ricerca in ampiezza. In contrasto con il metodo di ricerca in profondità dell'ultima sfida, La ricerca in ampiezza esplora tutti i nodi in un dato livello all'interno di un albero prima di continuare al livello successivo. Tipicamente, le code sono utilizzate come strutture di dati helper nella progettazione di algoritmi di ricerca in ampiezza.
 
-In this method, we start by adding the root node to a queue. Then we begin a loop where we dequeue the first item in the queue, add it to a new array, and then inspect both its child subtrees. If its children are not null, they are each enqueued. This process continues until the queue is empty.
+In questo metodo, iniziamo aggiungendo il nodo radice alla coda. Poi iniziamo un ciclo in cui decodiamo il primo elemento nella coda, aggiungerlo a un nuovo array, e quindi ispezionare entrambi i suoi sottalberi. Se i suoi figli non sono nulli, sono ciascuno messo in coda. Questo processo continua fino a quando la coda non è vuota.
 
 # --instructions--
 
-Let's create a breadth-first search method in our tree called `levelOrder`. This method should return an array containing the values of all the tree nodes, explored in a breadth-first manner. Be sure to return the values in the array, not the nodes themselves. A level should be traversed from left to right. Next, let's write a similar method called `reverseLevelOrder` which performs the same search but in the reverse direction (right to left) at each level.
+Creiamo un metodo di ricerca in ampiezza nel nostro albero chiamato `levelOrder`. Questo metodo dovrebbe restituire un array contenente i valori di tutti i nodi degli alberi, esplorati con la ricerca in ampiezza. Assicurati di restituire i valori nell'array, non i nodi stessi. Un livello dovrebbe essere attraversato da sinistra a destra. Poi scriviamo un metodo simile chiamato `reverseLevelOrder` che esegue la stessa ricerca ma nella direzione inversa (da destra a sinistra) ad ogni livello.
 
 # --hints--
 
-The `BinarySearchTree` data structure should exist.
+La struttura di dati `BinarySearchTree` dovrebbe esistere.
 
 ```js
 assert(
@@ -32,7 +32,7 @@ assert(
 );
 ```
 
-The binary search tree should have a method called `levelOrder`.
+L'albero di ricerca binario dovrebbe avere un metodo chiamato `levelOrder`.
 
 ```js
 assert(
@@ -48,7 +48,7 @@ assert(
 );
 ```
 
-The binary search tree should have a method called `reverseLevelOrder`.
+L'albero di ricerca binario dovrebbe avere un metodo chiamato `reverseLevelOrder`.
 
 ```js
 assert(
@@ -64,7 +64,7 @@ assert(
 );
 ```
 
-The `levelOrder` method should return an array of the tree node values explored in level order.
+Il metodo `levelOrder` dovrebbe restituire un array dei valori del nodo albero esplorati in ordine di livello.
 
 ```js
 assert(
@@ -94,7 +94,7 @@ assert(
 );
 ```
 
-The `reverseLevelOrder` method should return an array of the tree node values explored in reverse level order.
+Il metodo `reverseLevelOrder` dovrebbe restituire un array dei valori del nodo albero esplorati in ordine di livello inverso.
 
 ```js
 assert(
@@ -124,7 +124,7 @@ assert(
 );
 ```
 
-The `levelOrder` method should return `null` for an empty tree.
+Il metodo `levelOrder` dovrebbe restituire `null` per un albero vuoto.
 
 ```js
 assert(
@@ -143,7 +143,7 @@ assert(
 );
 ```
 
-The `reverseLevelOrder` method should return `null` for an empty tree.
+Il metodo `reverseLevelOrder` dovrebbe restituire `null` per un albero vuoto.
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/use-depth-first-search-in-a-binary-search-tree.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/use-depth-first-search-in-a-binary-search-tree.md
index c03fb750777..10ac9046c93 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/use-depth-first-search-in-a-binary-search-tree.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/use-depth-first-search-in-a-binary-search-tree.md
@@ -1,6 +1,6 @@
 ---
 id: 587d8257367417b2b2512c7e
-title: Use Depth First Search in a Binary Search Tree
+title: Usa la ricerca in profondità in un alvero di ricerca binario
 challengeType: 1
 forumTopicId: 301719
 dashedName: use-depth-first-search-in-a-binary-search-tree
@@ -8,15 +8,15 @@ dashedName: use-depth-first-search-in-a-binary-search-tree
 
 # --description--
 
-We know how to search a binary search tree for a specific value. But what if we just want to explore the entire tree? Or what if we don't have an ordered tree and we need to just search for a value? Here we will introduce some tree traversal methods which can be used to explore tree data structures. First up is depth-first search. In depth-first search, a given subtree is explored as deeply as possible before the search continues on to another subtree. There are three ways this can be done: In-order: Begin the search at the left-most node and end at the right-most node. Pre-order: Explore all the roots before the leaves. Post-order: Explore all the leaves before the roots. As you may guess, you may choose different search methods depending on what type of data your tree is storing and what you are looking for. For a binary search tree, an inorder traversal returns the nodes in sorted order.
+Sappiamo come cercare un albero di ricerca binario per un valore specifico. Ma cosa succede se vogliamo solo esplorare l'intero albero? O cosa succede se non abbiamo un albero ordinato e dobbiamo solo cercare un valore? Qui introdurremo alcuni metodi di per traversare l'alvero che possono essere utilizzati per esplorare strutture dati ad albero. Il primo è la prima ricerca in profondità. Nella ricerca in profondità, un dato sotto-albero è esplorato il più profondamente possibile prima che la ricerca continui su un altro sotto-albero. Ci sono tre modi per farlo: In ordine: Iniziare la ricerca al nodo più a sinistra e terminare al nodo più a destra. Pre-ordine: Esplora tutte le radici prima delle foglie. Post-order: Esplora tutte le foglie prima delle radici. Come si può immaginare, è possibile scegliere diversi metodi di ricerca a seconda del tipo di dati che l'albero sta memorizzando e quello che stai cercando. Per un albero di ricerca binario, un attraversamento in ordine restituisce i nodi ordinati.
 
 # --instructions--
 
-Here we will create these three search methods on our binary search tree. Depth-first search is an inherently recursive operation which continues to explore further subtrees so long as child nodes are present. Once you understand this basic concept, you can simply rearrange the order in which you explore the nodes and subtrees to produce any of the three searches above. For example, in post-order search we would want to recurse all the way to a leaf node before we begin to return any of the nodes themselves, whereas in pre-order search we would want to return the nodes first, and then continue recursing down the tree. Define `inorder`, `preorder`, and `postorder` methods on our tree. Each of these methods should return an array of items which represent the tree traversal. Be sure to return the integer values at each node in the array, not the nodes themselves. Finally, return `null` if the tree is empty.
+Qui creeremo questi tre metodi di ricerca sul nostro albero di ricerca binario. La ricerca di profondità prima è un'operazione intrinsecamente ricorsiva che continua ad esplorare ulteriori sottalberi, a condizione che siano presenti nodi figli. Una volta che capisci questo concetto fondamentale, si può semplicemente riorganizzare l'ordine in cui si esplorano i nodi e sotto-alberi per produrre una delle tre ricerche sopra. Ad esempio, nella ricerca post-ordine vorremmo arrivare ad un nodo foglia prima di iniziare a restituire uno dei nodi stessi, mentre in pre-ordine di ricerca vorremmo restituire i nodi prima, e poi continuare a ricorsare giù l'albero. Definisci i metodi `inorder`, `preorder`e `postorder` sul nostro albero. Ognuno di questi metodi dovrebbe restituire una serie di oggetti che rappresentano il traversale ad albero. Assicurati di restituire i valori interi ad ogni nodo dell'array, non i nodi stessi. Infine, restituisci `null` se l'albero è vuoto.
 
 # --hints--
 
-The `BinarySearchTree` data structure should exist.
+La struttura dati `BinarySearchTree` dovrebbe esistere.
 
 ```js
 assert(
@@ -30,7 +30,7 @@ assert(
 );
 ```
 
-The binary search tree should have a method called `inorder`.
+L'albero di ricerca binario dovrebbe avere un metodo chiamato `inorder`.
 
 ```js
 assert(
@@ -46,7 +46,7 @@ assert(
 );
 ```
 
-The binary search tree should have a method called `preorder`.
+L'albero di ricerca binario dovrebbe avere un metodo chiamato `preorder`.
 
 ```js
 assert(
@@ -62,7 +62,7 @@ assert(
 );
 ```
 
-The binary search tree should have a method called `postorder`.
+L'albero di ricerca binario dovrebbe avere un metodo chiamato `postorder`.
 
 ```js
 assert(
@@ -78,7 +78,7 @@ assert(
 );
 ```
 
-The `inorder` method should return an array of the node values that result from an inorder traversal.
+Il metodo `inorder` dovrebbe restituire un array dei valori del nodo che risultano da un traversamento inorder.
 
 ```js
 assert(
@@ -108,7 +108,7 @@ assert(
 );
 ```
 
-The `preorder` method should return an array of the node values that result from a preorder traversal.
+Il metodo `preorder` dovrebbe restituire un array dei valori del nodo che risultano da un attraversamento preorder.
 
 ```js
 assert(
@@ -138,7 +138,7 @@ assert(
 );
 ```
 
-The `postorder` method should return an array of the node values that result from a postorder traversal.
+Il metodo `postorder` dovrebbe restituire un array dei valori del nodo che risultano da un traversamento postordine.
 
 ```js
 assert(
@@ -168,7 +168,7 @@ assert(
 );
 ```
 
-The `inorder` method should return `null` for an empty tree.
+Il metodo `inorder` dovrebbe restituire `null` per un albero vuoto.
 
 ```js
 assert(
@@ -187,7 +187,7 @@ assert(
 );
 ```
 
-The `preorder` method should return `null` for an empty tree.
+Il metodo `preorder` dovrebbe restituire `null` per un albero vuoto.
 
 ```js
 assert(
@@ -206,7 +206,7 @@ assert(
 );
 ```
 
-The `postorder` method should return `null` for an empty tree.
+Il metodo `postorder` dovrebbe restituire `null` per un albero vuoto.
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/use-spread-and-notes-for-es5-set-integration.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/use-spread-and-notes-for-es5-set-integration.md
index 79ba7313b8c..42690e7ac78 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/use-spread-and-notes-for-es5-set-integration.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/use-spread-and-notes-for-es5-set-integration.md
@@ -1,6 +1,6 @@
 ---
 id: 587d8255367417b2b2512c73
-title: Use Spread and Notes for ES5 Set() Integration
+title: Usare sprea e notes per integrazione del Set() ES5
 challengeType: 1
 forumTopicId: 301720
 dashedName: use-spread-and-notes-for-es5-set-integration
@@ -8,11 +8,11 @@ dashedName: use-spread-and-notes-for-es5-set-integration
 
 # --description--
 
-Do you remember the ES6 spread operator `...`?
+Ricordi l'operatore di diffusione in ES6 `...`?
 
-`...` can take iterable objects in ES6 and turn them into arrays.
+`...` può prendere oggetti iterabili in ES6 e trasformarli in array.
 
-Let's create a Set, and check out the spread function.
+Creiamo un Set e controlliamo la funzione di diffusione.
 
 ```js
 var set = new Set([1,2,3]);
@@ -22,13 +22,13 @@ console.log(setToArr) // returns [ 1, 2, 3 ]
 
 # --instructions--
 
-In this exercise we will pass a set object to the `checkSet` function. It should return an array containing the values of the Set.
+In questo esercizio passeremo un oggetto set alla funzione `checkSet`. Dovrebbe restituire un array contenente i valori del Set.
 
-Now you've successfully learned how to use the ES6 `Set()` object, good job!
+Ora hai imparato con successo come usare l'oggetto ES6 `Set()`, buon lavoro!
 
 # --hints--
 
-`checkSet(new Set([1,2,3,4,5,6,7])` should return `[1, 2, 3, 4, 5, 6, 7]`.
+`checkSet(new Set([1,2,3,4,5,6,7])` dovrebbe restituire `[1, 2, 3, 4, 5, 6, 7]`.
 
 ```js
 assert(
diff --git a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/work-with-nodes-in-a-linked-list.md b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/work-with-nodes-in-a-linked-list.md
index c746995d5db..56bd0ae14c4 100644
--- a/curriculum/challenges/italian/10-coding-interview-prep/data-structures/work-with-nodes-in-a-linked-list.md
+++ b/curriculum/challenges/italian/10-coding-interview-prep/data-structures/work-with-nodes-in-a-linked-list.md
@@ -1,6 +1,6 @@
 ---
 id: 587d8251367417b2b2512c61
-title: Work with Nodes in a Linked List
+title: Lavorare con i nodi in una lista concatenata
 challengeType: 1
 forumTopicId: 301721
 dashedName: work-with-nodes-in-a-linked-list
@@ -8,25 +8,25 @@ dashedName: work-with-nodes-in-a-linked-list
 
 # --description--
 
-Another common data structure you'll run into in computer science is the <dfn>linked list</dfn>. A linked list is a linear collection of data elements, called 'nodes', each of which points to the next. Each <dfn>node</dfn> in a linked list contains two key pieces of information: the `element` itself, and a reference to the next `node`.
+Un'altra struttura dati che incontrerai in computer science è la <dfn>lista concatenata</dfn>. Una lista concatenata è una collezione lineare di elementi di dati, chiamati nodi, ognuno dei quali fa riferimento al successivo. Ogni <dfn>nodo</dfn> in una lista concatenata contiene due informazioni fondamentali: l'elemento stesso, e un riferimento al nodo successivo.
 
-Imagine that you are in a conga line. You have your hands on the next person in the line, and the person behind you has their hands on you. You can see the person straight ahead of you, but they are blocking the view of the other people ahead in line. A node is just like a person in a conga line: they know who they are and they can only see the next person in line, but they are not aware of the other people ahead or behind them.
+Immagina di essere in un trenino. Hai le mani sulle spalle della persona davanti a te in fila, e la persona dietro di te ha le mani sulle tue spalle. Puoi vedere la persona direttamente di fronte a te, ma stanno bloccando la vista delle altre persone più in la nel trenino. Un nodo è proprio come una persona in un trenino: sanno chi sono e possono vedere solo la persona successiva nella fila, ma non sono a conoscenza delle altre persone davanti o dietro di loro.
 
 # --instructions--
 
-In our code editor, we've created two nodes, `Kitten` and `Puppy`, and we've manually connected the `Kitten` node to the `Puppy` node.
+Nel nostro editor di codice, abbiamo creato due noti, `Kitten` e `Puppy`, e abbiamo connesso il nodo `Kitten` al nodo`Puppy`.
 
-Create a `Cat` and `Dog` node and manually add them to the line.
+Crea dei nodi `Cat` e `Dog` e aggiungili manualmente alla lista.
 
 # --hints--
 
-Your `Puppy` node should have a reference to a `Cat` node.
+Il tuo nodo `Puppy` dovrebbe avere un riferimento a un nodo `Cat`.
 
 ```js
 assert(Puppy.next.element === 'Cat');
 ```
 
-Your `Cat` node should have a reference to a `Dog` node.
+Il tuo nodo `Cat` dovrebbe avere un riferimento a un nodo `Dog`.
 
 ```js
 assert(Cat.next.element === 'Dog');
diff --git a/curriculum/challenges/portuguese/01-responsive-web-design/applied-accessibility/use-headings-to-show-hierarchical-relationships-of-content.md b/curriculum/challenges/portuguese/01-responsive-web-design/applied-accessibility/use-headings-to-show-hierarchical-relationships-of-content.md
index 46c696b8509..ccdad503aa7 100644
--- a/curriculum/challenges/portuguese/01-responsive-web-design/applied-accessibility/use-headings-to-show-hierarchical-relationships-of-content.md
+++ b/curriculum/challenges/portuguese/01-responsive-web-design/applied-accessibility/use-headings-to-show-hierarchical-relationships-of-content.md
@@ -17,7 +17,7 @@ Se você estivesse escrevendo um artigo com uma introdução, um corpo e uma con
 
 Títulos com classificação igual (ou superior) iniciam novas seções, títulos com classificação inferior começam subseções dentro da seção pai.
 
-Por exemplo: uma página com um elemento `h2` seguido por várias subseções rotuladas com tags `h4` confundiria um usuário de leitor de tela. Como o HTML5 oferece 6 opções de títulos, pode ser tentador usar uma dessas tags apenas pelo tamanho da fonte que elas oferecem, mas você pode usar o CSS para alterar estes tamanhos.
+Por exemplo: uma página com um elemento `h2` seguido por várias subseções rotuladas com elementos `h4` confundiria um usuário de leitor de tela. Como o HTML5 oferece 6 opções de títulos, pode ser tentador usar uma dessas tags apenas pelo tamanho da fonte que elas oferecem, mas você pode usar o CSS para alterar estes tamanhos.
 
 Uma última observação, cada página deve sempre ter um (e apenas um) elemento `h1`, que é o assunto principal do seu conteúdo. Este e outros cabeçalhos são usados ​​em parte pelos mecanismos de pesquisa para entender o tópico da página.
 
@@ -27,7 +27,7 @@ O Camper Cat quer uma página no site dedicada a como se tornar um ninja. Ajude-
 
 # --hints--
 
-O código deve ter 6 tags `h3`.
+O código deve ter 6 elementos `h3`.
 
 ```js
 assert($('h3').length === 6);
@@ -39,7 +39,7 @@ O código deve ter 6 tags de fechamento `h3`.
 assert((code.match(/\/h3/g) || []).length === 6);
 ```
 
-O código não deve ter nenhuma tag `h5`.
+O código não deve ter nenhum elemento `h5`.
 
 ```js
 assert($('h5').length === 0);
diff --git a/curriculum/challenges/portuguese/01-responsive-web-design/applied-visual-design/adjust-the-size-of-a-heading-element-versus-a-paragraph-element.md b/curriculum/challenges/portuguese/01-responsive-web-design/applied-visual-design/adjust-the-size-of-a-heading-element-versus-a-paragraph-element.md
index 9191d7cdecb..60d1c320b7c 100644
--- a/curriculum/challenges/portuguese/01-responsive-web-design/applied-visual-design/adjust-the-size-of-a-heading-element-versus-a-paragraph-element.md
+++ b/curriculum/challenges/portuguese/01-responsive-web-design/applied-visual-design/adjust-the-size-of-a-heading-element-versus-a-paragraph-element.md
@@ -1,6 +1,6 @@
 ---
 id: 587d781b367417b2b2512abd
-title: Contrastar o tamanho de um título com o de um parágrafo
+title: Contrastar o tamanho de um elemento de título com o de um parágrafo
 challengeType: 0
 videoUrl: 'https://scrimba.com/c/c3bRPTz'
 forumTopicId: 301037
@@ -9,11 +9,11 @@ dashedName: adjust-the-size-of-a-heading-element-versus-a-paragraph-element
 
 # --description--
 
-O tamanho da tipografia das tags de títulos (`h1` a `h6`) geralmente deve ser maior do que o tamanho da tipografia das tags de parágrafo. Isso torna mais fácil para o usuário entender visualmente o layout e o nível de importância de tudo na página. Você pode usar a propriedade `font-size` para ajustar o tamanho do texto de um elemento.
+O tamanho da tipografia dos elementos de título (`h1` a `h6`) geralmente deve ser maior do que o tamanho da tipografia dos elementos de parágrafo. Isso torna mais fácil para o usuário entender visualmente o layout e o nível de importância de tudo na página. Você pode usar a propriedade `font-size` para ajustar o tamanho do texto de um elemento.
 
 # --instructions--
 
-Para tornar o título significativamente maior do que o parágrafo, altere a propriedade `font-size` da tag `h4` para 27 pixels.
+Para tornar o título significativamente maior do que o parágrafo, altere a propriedade `font-size` do elemento `h4` para 27 pixels.
 
 # --hints--
 
@@ -116,3 +116,4 @@ assert($('h4').css('font-size') == '27px');
   </div>
 </div>
 ```
+
diff --git a/curriculum/challenges/portuguese/01-responsive-web-design/applied-visual-design/create-visual-balance-using-the-text-align-property.md b/curriculum/challenges/portuguese/01-responsive-web-design/applied-visual-design/create-visual-balance-using-the-text-align-property.md
index 753a7fbe104..0934b187dae 100644
--- a/curriculum/challenges/portuguese/01-responsive-web-design/applied-visual-design/create-visual-balance-using-the-text-align-property.md
+++ b/curriculum/challenges/portuguese/01-responsive-web-design/applied-visual-design/create-visual-balance-using-the-text-align-property.md
@@ -13,7 +13,7 @@ Esta seção do currículo se concentra no Design Visual Aplicado. O primeiro gr
 
 O texto costuma ser uma grande parte do conteúdo na web. O CSS possui várias opções de como alinhá-lo com a propriedade `text-align`.
 
-`text-align: justify;` faz com que todas as linhas de texto, exceto a última linha, encostem nas bordas esquerda e direita da caixa em que o texto está.
+`text-align: justify;` espaça o texto para que cada linha tenha a mesma largura.
 
 `text-align: center;` centraliza o texto
 
diff --git a/curriculum/challenges/portuguese/01-responsive-web-design/applied-visual-design/use-the-s-tag-to-strikethrough-text.md b/curriculum/challenges/portuguese/01-responsive-web-design/applied-visual-design/use-the-s-tag-to-strikethrough-text.md
index c0b5dfaf561..f6e39e902bd 100644
--- a/curriculum/challenges/portuguese/01-responsive-web-design/applied-visual-design/use-the-s-tag-to-strikethrough-text.md
+++ b/curriculum/challenges/portuguese/01-responsive-web-design/applied-visual-design/use-the-s-tag-to-strikethrough-text.md
@@ -13,7 +13,7 @@ Para deixar o texto tachado, ou seja, para que uma linha horizontal corte os car
 
 # --instructions--
 
-Envolva a tag `s` em torno da palavra `Google` que está dentro da tag `h4` e, em seguida, adicione a palavra `Alphabet` ao lado dela. Essa segunda palavra não deverá estar tachada.
+Envolva a tag `s` em torno da palavra `Google` que está dentro da tag `h4` e, em seguida, adicione a palavra `Alphabet` ao lado dela sem a formatação tachada.
 
 # --hints--
 
diff --git a/curriculum/challenges/portuguese/01-responsive-web-design/basic-html-and-html5/link-to-internal-sections-of-a-page-with-anchor-elements.md b/curriculum/challenges/portuguese/01-responsive-web-design/basic-html-and-html5/link-to-internal-sections-of-a-page-with-anchor-elements.md
index ed9593d27da..338d88dd2e6 100644
--- a/curriculum/challenges/portuguese/01-responsive-web-design/basic-html-and-html5/link-to-internal-sections-of-a-page-with-anchor-elements.md
+++ b/curriculum/challenges/portuguese/01-responsive-web-design/basic-html-and-html5/link-to-internal-sections-of-a-page-with-anchor-elements.md
@@ -21,7 +21,7 @@ Abaixo, vemos um exemplo de um link vinculado a um elemento interno da página:
 <h2 id="contacts-header">Contacts</h2>
 ```
 
-Quando os usuários clicam no link `Contacts`, eles são levados à seção da página que contem o texto **Contacts**.
+Quando os usuários clicam no link `Contacts`, eles são levados à seção da página que contem o elemento de título **Contacts**.
 
 # --instructions--
 
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md
index 889331b47a9..07b2f13da18 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/access-array-data-with-indexes.md
@@ -18,9 +18,9 @@ Os índices de um array são escritos na mesma notação com colchetes que as st
 **Exemplo**
 
 ```js
-var array = [50,60,70];
+const array = [50, 60, 70];
 array[0];
-var data = array[1];
+const data = array[1];
 ```
 
 `array[0]` agora é `50` e `data` tem o valor `60`.
@@ -76,7 +76,7 @@ if(typeof myArray !== "undefined" && typeof myData !== "undefined"){(function(y,
 ## --seed-contents--
 
 ```js
-var myArray = [50,60,70];
+const myArray = [50, 60, 70];
 
 
 ```
@@ -84,6 +84,6 @@ var myArray = [50,60,70];
 # --solutions--
 
 ```js
-var myArray = [50,60,70];
-var myData = myArray[0];
+const myArray = [50, 60, 70];
+const myData = myArray[0];
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md
index 841e4979419..60d8694b952 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/access-multi-dimensional-arrays-with-indexes.md
@@ -14,12 +14,13 @@ Uma maneira de pensar em um array <dfn>multidimensional</dfn> é como um *array
 **Exemplo**
 
 ```js
-var arr = [
-  [1,2,3],
-  [4,5,6],
-  [7,8,9],
-  [[10,11,12], 13, 14]
+const arr = [
+  [1, 2, 3],
+  [4, 5, 6],
+  [7, 8, 9],
+  [[10, 11, 12], 13, 14]
 ];
+
 arr[3];
 arr[3][0];
 arr[3][0][1];
@@ -58,14 +59,19 @@ if(typeof myArray !== "undefined"){(function(){return "myData: " + myData + " my
 ## --seed-contents--
 
 ```js
-var myArray = [[1,2,3], [4,5,6], [7,8,9], [[10,11,12], 13, 14]];
+const myArray = [
+  [1, 2, 3],
+  [4, 5, 6],
+  [7, 8, 9],
+  [[10, 11, 12], 13, 14],
+];
 
-var myData = myArray[0][0];
+const myData = myArray[0][0];
 ```
 
 # --solutions--
 
 ```js
-var myArray = [[1,2,3],[4,5,6], [7,8,9], [[10,11,12], 13, 14]];
-var myData = myArray[2][1];
+const myArray = [[1, 2, 3], [4, 5, 6], [7, 8, 9], [[10, 11, 12], 13, 14]];
+const myData = myArray[2][1];
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md
index d403cac91f1..e8b7c5e3c9c 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md
@@ -14,7 +14,7 @@ Como vimos em exemplos anteriores, objetos podem conter tanto objetos aninhados
 Aqui está um exemplo de como se acessar um array aninhado:
 
 ```js
-var ourPets = [
+const ourPets = [
   {
     animalType: "cat",
     names: [
@@ -32,6 +32,7 @@ var ourPets = [
     ]
   }
 ];
+
 ourPets[0].names[1];
 ourPets[1].names[0];
 ```
@@ -72,7 +73,7 @@ assert(/=\s*myPlants\[1\].list\[1\]/.test(code));
 ## --seed-contents--
 
 ```js
-var myPlants = [
+const myPlants = [
   {
     type: "flowers",
     list: [
@@ -91,13 +92,13 @@ var myPlants = [
   }
 ];
 
-var secondTree = "";
+const secondTree = "";
 ```
 
 # --solutions--
 
 ```js
-var myPlants = [
+const myPlants = [
   {
     type: "flowers",
     list: [
@@ -116,5 +117,5 @@ var myPlants = [
   }
 ];
 
-var secondTree = myPlants[1].list[1];
+const secondTree = myPlants[1].list[1];
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md
index 26dc990f757..1cab5c28117 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-objects.md
@@ -14,7 +14,7 @@ As subpropriedades de objetos podem ser acessadas ao encadear a notação de pon
 Aqui está um objeto aninhado:
 
 ```js
-var ourStorage = {
+const ourStorage = {
   "desk": {
     "drawer": "stapler"
   },
@@ -26,6 +26,7 @@ var ourStorage = {
     "bottom drawer": "soda"
   }
 };
+
 ourStorage.cabinet["top drawer"].folder2;
 ourStorage.desk.drawer;
 ```
@@ -66,7 +67,7 @@ assert(/=\s*myStorage\.car\.inside\[\s*("|')glove box\1\s*\]/g.test(code));
 ## --seed-contents--
 
 ```js
-var myStorage = {
+const myStorage = {
   "car": {
     "inside": {
       "glove box": "maps",
@@ -78,13 +79,13 @@ var myStorage = {
   }
 };
 
-var gloveBoxContents = undefined;
+const gloveBoxContents = undefined;
 ```
 
 # --solutions--
 
 ```js
-var myStorage = {
+const myStorage = {
   "car":{
     "inside":{
       "glove box":"maps",
@@ -95,5 +96,5 @@ var myStorage = {
     }
   }
 };
-var gloveBoxContents = myStorage.car.inside["glove box"];
+const gloveBoxContents = myStorage.car.inside["glove box"];
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md
index a906f8fc95a..5986eb8a2e1 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.md
@@ -16,11 +16,12 @@ No entanto, você ainda pode usar a notação de colchetes nas propriedades dos
 Aqui está um exemplo usando a notação de colchetes para ler uma propriedade de um objeto:
 
 ```js
-var myObj = {
+const myObj = {
   "Space Name": "Kirk",
   "More Space": "Spock",
   "NoSpace": "USS Enterprise"
 };
+
 myObj["Space Name"];
 myObj['More Space'];
 myObj["NoSpace"];
@@ -78,26 +79,25 @@ assert(code.match(/testObj\s*?\[('|")[^'"]+\1\]/g).length > 1);
 
 ```js
 // Setup
-var testObj = {
+const testObj = {
   "an entree": "hamburger",
   "my side": "veggies",
   "the drink": "water"
 };
 
 // Only change code below this line
-
-var entreeValue = testObj;   // Change this line
-var drinkValue = testObj;    // Change this line
+const entreeValue = testObj;   // Change this line
+const drinkValue = testObj;    // Change this line
 ```
 
 # --solutions--
 
 ```js
-var testObj = {
+const testObj = {
   "an entree": "hamburger",
   "my side": "veggies",
   "the drink": "water"
 };
-var entreeValue = testObj["an entree"];
-var drinkValue = testObj['the drink'];
+const entreeValue = testObj["an entree"];
+const drinkValue = testObj['the drink'];
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md
index e9f70fe6ea5..2b02189601c 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-dot-notation.md
@@ -16,15 +16,17 @@ Notação de ponto é o que você utiliza quando você sabe o nome da propriedad
 Aqui está um exemplo usando notação de ponto (`.`) para ler uma propriedade do objeto:
 
 ```js
-var myObj = {
+const myObj = {
   prop1: "val1",
   prop2: "val2"
 };
-var prop1val = myObj.prop1;
-var prop2val = myObj.prop2;
+
+const prop1val = myObj.prop1;
+const prop2val = myObj.prop2;
 ```
 
 `prop1val` teria o valor `val1` e `prop2val` teria o valor `val2`.
+
 # --instructions--
 
 Leia os valores de propriedade de `testObj` usando a notação de ponto. Defina a variável `hatValue` igual à propriedade `hat` do objeto e defina a variável `shirtValue` igual à propriedade `shirt` do objeto.
@@ -73,27 +75,26 @@ assert(code.match(/testObj\.\w+/g).length > 1);
 
 ```js
 // Setup
-var testObj = {
+const testObj = {
   "hat": "ballcap",
   "shirt": "jersey",
   "shoes": "cleats"
 };
 
 // Only change code below this line
-
-var hatValue = testObj;      // Change this line
-var shirtValue = testObj;    // Change this line
+const hatValue = testObj;      // Change this line
+const shirtValue = testObj;    // Change this line
 ```
 
 # --solutions--
 
 ```js
-var testObj = {
+const testObj = {
   "hat": "ballcap",
   "shirt": "jersey",
   "shoes": "cleats"
 };
 
-var hatValue = testObj.hat;
-var shirtValue = testObj.shirt;
+const hatValue = testObj.hat;
+const shirtValue = testObj.shirt;
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md
index cd5cfc3d58c..80ef872b157 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables.md
@@ -14,11 +14,14 @@ Outro uso de notação de colchetes em objetos é para acessar a propriedade a q
 Aqui está um exemplo de usar uma variável para acessar uma propriedade:
 
 ```js
-var dogs = {
-  Fido: "Mutt",  Hunter: "Doberman",  Snoopie: "Beagle"
+const dogs = {
+  Fido: "Mutt",
+  Hunter: "Doberman",
+  Snoopie: "Beagle"
 };
-var myDog = "Hunter";
-var myBreed = dogs[myDog];
+
+const myDog = "Hunter";
+const myBreed = dogs[myDog];
 console.log(myBreed);
 ```
 
@@ -27,14 +30,16 @@ A string `Doberman` seria exibida no console.
 Outra forma de você usar esse conceito é quando o nome da propriedade é coletado dinamicamente, durante a execução do programa, da seguinte forma:
 
 ```js
-var someObj = {
+const someObj = {
   propName: "John"
 };
+
 function propPrefix(str) {
-  var s = "prop";
+  const s = "prop";
   return s + str;
 }
-var someProp = propPrefix("Name");
+
+const someProp = propPrefix("Name");
 console.log(someObj[someProp]);
 ```
 
@@ -96,26 +101,25 @@ if(typeof player !== "undefined"){(function(v){return v;})(player);}
 
 ```js
 // Setup
-var testObj = {
+const testObj = {
   12: "Namath",
   16: "Montana",
   19: "Unitas"
 };
 
 // Only change code below this line
-
-var playerNumber;       // Change this line
-var player = testObj;   // Change this line
+const playerNumber = 42;  // Change this line
+const player = testObj;   // Change this line
 ```
 
 # --solutions--
 
 ```js
-var testObj = {
+const testObj = {
   12: "Namath",
   16: "Montana",
   19: "Unitas"
 };
-var playerNumber = 16;
-var player = testObj[playerNumber];
+const playerNumber = 16;
+const player = testObj[playerNumber];
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md
index 536482c962f..7c321d33e3e 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/add-new-properties-to-a-javascript-object.md
@@ -28,7 +28,7 @@ Agora, quando acessamos `ourDog.bark`, nós teremos o seu latido, `bow-wow`.
 Exemplo:
 
 ```js
-var ourDog = {
+const ourDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
@@ -67,7 +67,7 @@ assert(!/bark[^\n]:/.test(code));
 ## --seed-contents--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
@@ -80,7 +80,7 @@ var myDog = {
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md
index 5b432e15a4b..d9d0552b855 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/add-two-numbers-with-javascript.md
@@ -18,7 +18,7 @@ JavaScript utiliza o símbolo `+` como um operador de adição quando colocado e
 **Exemplo:**
 
 ```js
-myVar = 5 + 10;
+const myVar = 5 + 10;
 ```
 
 `myVar` agora tem o valor de `15`.
@@ -52,11 +52,11 @@ assert(/\+/.test(code));
 ## --seed-contents--
 
 ```js
-var sum = 10 + 0;
+const sum = 10 + 0;
 ```
 
 # --solutions--
 
 ```js
-var sum = 10 + 10;
+const sum = 10 + 10;
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md
index cf93fe09a4b..beffc0750b1 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/adding-a-default-option-in-switch-statements.md
@@ -92,7 +92,7 @@ assert(code.match(/break/g).length > 2);
 
 ```js
 function switchOfStuff(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
 
@@ -108,7 +108,7 @@ switchOfStuff(1);
 
 ```js
 function switchOfStuff(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case "a":
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md
index 987a2387a12..06d6a5f57ad 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/appending-variables-to-strings.md
@@ -14,8 +14,8 @@ Assim como podemos construir uma string em várias linhas através das strings <
 Exemplo:
 
 ```js
-var anAdjective = "awesome!";
-var ourStr = "freeCodeCamp is ";
+const anAdjective = "awesome!";
+let ourStr = "freeCodeCamp is ";
 ourStr += anAdjective;
 ```
 
@@ -64,15 +64,14 @@ assert(code.match(/myStr\s*\+=\s*someAdjective\s*/).length > 0);
 
 ```js
 // Change code below this line
-
-var someAdjective;
-var myStr = "Learning to code is ";
+const someAdjective = "";
+let myStr = "Learning to code is ";
 ```
 
 # --solutions--
 
 ```js
-var someAdjective = "neat";
-var myStr = "Learning to code is ";
+const someAdjective = "neat";
+let myStr = "Learning to code is ";
 myStr += someAdjective;
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md
index fb9682c4d65..5032a5a25fc 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.md
@@ -18,7 +18,7 @@ Objetos são úteis para armazenar dados de forma estruturada e podem representa
 Aqui está um exemplo de objeto gato:
 
 ```js
-var cat = {
+const cat = {
   "name": "Whiskers",
   "legs": 4,
   "tails": 1,
@@ -29,7 +29,7 @@ var cat = {
 Neste exemplo, todas as propriedades são armazenadas como strings, como `name`, `legs` e `tails`. Porém, você também pode usar números como propriedades. Você pode até omitir as aspas para propriedades de string com uma única palavra, da seguinte forma:
 
 ```js
-var anotherObject = {
+const anotherObject = {
   make: "Ford",
   5: "five",
   "model": "focus"
@@ -139,18 +139,18 @@ assert(
 ## --seed-contents--
 
 ```js
-var myDog = {
-// Only change code below this line
+const myDog = {
+  // Only change code below this line
 
 
-// Only change code above this line
+  // Only change code above this line
 };
 ```
 
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md
index 5dbedae385d..94afde20019 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/comparison-with-the-equality-operator.md
@@ -16,7 +16,7 @@ O operador mais básico é o operador de igualdade `==`. O operador de igualdade
 ```js
 function equalityTest(myVal) {
   if (myVal == 10) {
-     return "Equal";
+    return "Equal";
   }
   return "Not Equal";
 }
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md
index 2c13e190d22..efb651fb177 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-addition.md
@@ -20,7 +20,7 @@ para adicionar `5` a `myVar`. Como este é um padrão tão comum, existem operad
 Um desses operadores é o operador `+=`.
 
 ```js
-var myVar = 1;
+let myVar = 1;
 myVar += 5;
 console.log(myVar);
 ```
@@ -61,9 +61,9 @@ Você não deve modificar o código acima do comentário especificado.
 
 ```js
 assert(
-  /var a = 3;/.test(code) &&
-    /var b = 17;/.test(code) &&
-    /var c = 12;/.test(code)
+  /let a = 3;/.test(code) &&
+    /let b = 17;/.test(code) &&
+    /let c = 12;/.test(code)
 );
 ```
 
@@ -78,9 +78,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 3;
-var b = 17;
-var c = 12;
+let a = 3;
+let b = 17;
+let c = 12;
 
 // Only change code below this line
 a = a + 12;
@@ -91,9 +91,9 @@ c = c + 7;
 # --solutions--
 
 ```js
-var a = 3;
-var b = 17;
-var c = 12;
+let a = 3;
+let b = 17;
+let c = 12;
 
 a += 12;
 b += 9;
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md
index bb4335d4e67..79574ac77de 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-division.md
@@ -55,9 +55,9 @@ Você não deve modificar o código acima do comentário especificado.
 
 ```js
 assert(
-  /var a = 48;/.test(code) &&
-    /var b = 108;/.test(code) &&
-    /var c = 33;/.test(code)
+  /let a = 48;/.test(code) &&
+    /let b = 108;/.test(code) &&
+    /let c = 33;/.test(code)
 );
 ```
 
@@ -72,9 +72,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 48;
-var b = 108;
-var c = 33;
+let a = 48;
+let b = 108;
+let c = 33;
 
 // Only change code below this line
 a = a / 12;
@@ -85,9 +85,9 @@ c = c / 11;
 # --solutions--
 
 ```js
-var a = 48;
-var b = 108;
-var c = 33;
+let a = 48;
+let b = 108;
+let c = 33;
 
 a /= 12;
 b /= 4;
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md
index 7b1f7ada71e..9ab507cf2c5 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-multiplication.md
@@ -55,9 +55,9 @@ Você não deve modificar o código acima do comentário especificado.
 
 ```js
 assert(
-  /var a = 5;/.test(code) &&
-    /var b = 12;/.test(code) &&
-    /var c = 4\.6;/.test(code)
+  /let a = 5;/.test(code) &&
+    /let b = 12;/.test(code) &&
+    /let c = 4\.6;/.test(code)
 );
 ```
 
@@ -72,9 +72,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 5;
-var b = 12;
-var c = 4.6;
+let a = 5;
+let b = 12;
+let c = 4.6;
 
 // Only change code below this line
 a = a * 5;
@@ -85,9 +85,9 @@ c = c * 10;
 # --solutions--
 
 ```js
-var a = 5;
-var b = 12;
-var c = 4.6;
+let a = 5;
+let b = 12;
+let c = 4.6;
 
 a *= 5;
 b *= 3;
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md
index 627741cc1d0..2dae4695cdc 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md
@@ -55,7 +55,7 @@ Você não deve modificar o código acima do comentário especificado.
 
 ```js
 assert(
-  /var a = 11;/.test(code) && /var b = 9;/.test(code) && /var c = 3;/.test(code)
+  /let a = 11;/.test(code) && /let b = 9;/.test(code) && /let c = 3;/.test(code)
 );
 ```
 
@@ -70,9 +70,9 @@ assert(
 ## --seed-contents--
 
 ```js
-var a = 11;
-var b = 9;
-var c = 3;
+let a = 11;
+let b = 9;
+let c = 3;
 
 // Only change code below this line
 a = a - 6;
@@ -83,9 +83,9 @@ c = c - 1;
 # --solutions--
 
 ```js
-var a = 11;
-var b = 9;
-var c = 3;
+let a = 11;
+let b = 9;
+let c = 3;
 
 a -= 6;
 b -= 15;
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md
index 71904013f21..2c093f2f84f 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md
@@ -16,7 +16,7 @@ Também podemos usar o operador `+=` para <dfn>concatenar</dfn> uma string no fi
 Exemplo:
 
 ```js
-var ourStr = "I come first. ";
+let ourStr = "I come first. ";
 ourStr += "I come second.";
 ```
 
@@ -57,14 +57,12 @@ assert(code.match(/myStr\s*\+=\s*(["']).*\1/g));
 ## --seed-contents--
 
 ```js
-// Only change code below this line
-
-var myStr;
+let myStr;
 ```
 
 # --solutions--
 
 ```js
-var myStr = "This is the first sentence. ";
+let myStr = "This is the first sentence. ";
 myStr += "This is the second sentence.";
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md
index 81f01b93126..82017bedc72 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/constructing-strings-with-variables.md
@@ -14,8 +14,8 @@ dashedName: constructing-strings-with-variables
 Exemplo:
 
 ```js
-var ourName = "freeCodeCamp";
-var ourStr = "Hello, our name is " + ourName + ", how are you?";
+const ourName = "freeCodeCamp";
+const ourStr = "Hello, our name is " + ourName + ", how are you?";
 ```
 
 `ourStr` teria o valor da string `Hello, our name is freeCodeCamp, how are you?`.
@@ -63,13 +63,13 @@ assert(code.match(/["']\s*\+\s*myName\s*\+\s*["']/g).length > 0);
 
 ```js
 // Only change code below this line
-var myName;
-var myStr;
+const myName = "";
+const myStr = "";
 ```
 
 # --solutions--
 
 ```js
-var myName = "Bob";
-var myStr = "My name is " + myName + " and I am well!";
+const myName = "Bob";
+const myStr = "My name is " + myName + " and I am well!";
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md
index 0581beaa383..5e8fb5b8cda 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/counting-cards.md
@@ -159,7 +159,7 @@ assert(
 ## --seed-contents--
 
 ```js
-var count = 0;
+let count = 0;
 
 function cc(card) {
   // Only change code below this line
@@ -175,7 +175,7 @@ cc(2); cc(3); cc(7); cc('K'); cc('A');
 # --solutions--
 
 ```js
-var count = 0;
+let count = 0;
 function cc(card) {
   switch(card) {
     case 2:
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md
index 748abf81d20..2690820cb7a 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/create-decimal-numbers-with-javascript.md
@@ -42,13 +42,14 @@ assert(myDecimal % 1 != 0);
 ## --seed-contents--
 
 ```js
-var ourDecimal = 5.7;
+const ourDecimal = 5.7;
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myDecimal = 9.9;
+const myDecimal = 9.9;
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md
index 29a3d15026d..bed512835eb 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/decrement-a-number-with-javascript.md
@@ -39,7 +39,7 @@ assert(myVar === 10);
 
 ```js
 assert(
-  /var\s*myVar\s*=\s*11;\s*\/*.*\s*([-]{2}\s*myVar|myVar\s*[-]{2});/.test(code)
+  /let\s*myVar\s*=\s*11;\s*\/*.*\s*([-]{2}\s*myVar|myVar\s*[-]{2});/.test(code)
 );
 ```
 
@@ -52,7 +52,7 @@ assert(/[-]{2}\s*myVar|myVar\s*[-]{2}/.test(code));
 Você não deve alterar o código acima do comentário especificado.
 
 ```js
-assert(/var myVar = 11;/.test(code));
+assert(/let myVar = 11;/.test(code));
 ```
 
 # --seed--
@@ -66,7 +66,7 @@ assert(/var myVar = 11;/.test(code));
 ## --seed-contents--
 
 ```js
-var myVar = 11;
+let myVar = 11;
 
 // Only change code below this line
 myVar = myVar - 1;
@@ -75,6 +75,6 @@ myVar = myVar - 1;
 # --solutions--
 
 ```js
-var myVar = 11;
+let myVar = 11;
 myVar--;
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md
index 45199937e1d..0934dfc7581 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/delete-properties-from-a-javascript-object.md
@@ -18,7 +18,7 @@ delete ourDog.bark;
 Exemplo:
 
 ```js
-var ourDog = {
+const ourDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
@@ -70,7 +70,7 @@ assert(code.match(/"tails": 1/g).length > 0);
 
 ```js
 // Setup
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
@@ -79,12 +79,13 @@ var myDog = {
 };
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Happy Coder",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md
index f08b9f39fe8..67117d004f5 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-decimal-by-another-with-javascript.md
@@ -46,11 +46,11 @@ assert(code.match(/quotient/g).length === 1);
 ## --seed-contents--
 
 ```js
-var quotient = 0.0 / 2.0; // Change this line
+const quotient = 0.0 / 2.0; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var quotient = 4.4 / 2.0;
+const quotient = 4.4 / 2.0;
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md
index 2cc53270324..0fe66dbf7d9 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/divide-one-number-by-another-with-javascript.md
@@ -16,7 +16,7 @@ JavaScript usa o símbolo `/` para divisão.
 **Exemplo**
 
 ```js
-myVar = 16 / 2;
+const myVar = 16 / 2;
 ```
 
 `myVar` agora possui o valor `8`.
@@ -49,11 +49,11 @@ assert(/\d+\s*\/\s*\d+/.test(code));
 ## --seed-contents--
 
 ```js
-var quotient = 66 / 0;
+const quotient = 66 / 0;
 ```
 
 # --solutions--
 
 ```js
-var quotient = 66 / 33;
+const quotient = 66 / 33;
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md
index c468fc17415..f808b75cb79 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/escape-sequences-in-strings.md
@@ -89,11 +89,11 @@ console.log('myStr:\n' + myStr);}})();
 ## --seed-contents--
 
 ```js
-var myStr; // Change this line
+const myStr = ""; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var myStr = "FirstLine\n\t\\SecondLine\nThirdLine";
+const myStr = "FirstLine\n\t\\SecondLine\nThirdLine";
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md
index 5558498f3e9..f3094105286 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/escaping-literal-quotes-in-strings.md
@@ -14,7 +14,7 @@ Quando você estiver definindo uma sequência de caracteres você deve iniciar e
 Em JavaScript, você pode <dfn>escapar</dfn> uma aspa para que não seja considerada como o fim de uma string ao colocar a <dfn>barra invertida</dfn> (`\`) na frente da aspa.
 
 ```js
-var sampleStr = "Alan said, \"Peter is learning JavaScript\".";
+const sampleStr = "Alan said, \"Peter is learning JavaScript\".";
 ```
 
 Isso sinaliza ao JavaScript que a aspa seguinte não é o fim de uma string, mas que deve aparecer dentro da string. Então, se você fosse imprimir isso no console, você obteria:
@@ -62,11 +62,11 @@ assert(/I am a "double quoted" string inside "double quotes(\."|"\.)$/.test(mySt
 ## --seed-contents--
 
 ```js
-var myStr = ""; // Change this line
+const myStr = ""; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var myStr = "I am a \"double quoted\" string inside \"double quotes\".";
+const myStr = "I am a \"double quoted\" string inside \"double quotes\".";
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md
index e58e42c0224..987b99767aa 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md
@@ -31,7 +31,7 @@ Define o `resto` igual ao restante de `11` dividido por `3` usando o operador de
 A variável `remainder` deve ser inicializada
 
 ```js
-assert(/var\s+?remainder/.test(code));
+assert(/(const|let|var)\s+?remainder/.test(code));
 ```
 
 O valor de `remainder` deve ser `2`
@@ -57,13 +57,11 @@ assert(/\s+?remainder\s*?=\s*?.*%.*;?/.test(code));
 ## --seed-contents--
 
 ```js
-// Only change code below this line
-
-var remainder;
+const remainder = 0;
 ```
 
 # --solutions--
 
 ```js
-var remainder =  11 % 3;
+const remainder = 11 % 3;
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md
index 5da50dd0d2c..d1a03237e60 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/global-vs.-local-scope-in-functions.md
@@ -14,9 +14,10 @@ dashedName: global-vs--local-scope-in-functions
 Neste exemplo:
 
 ```js
-var someVar = "Hat";
+const someVar = "Hat";
+
 function myFun() {
-  var someVar = "Head";
+  const someVar = "Head";
   return someVar;
 }
 ```
@@ -53,13 +54,11 @@ assert(/return outerWear/.test(code));
 
 ```js
 // Setup
-var outerWear = "T-Shirt";
+const outerWear = "T-Shirt";
 
 function myOutfit() {
   // Only change code below this line
 
-
-
   // Only change code above this line
   return outerWear;
 }
@@ -70,9 +69,9 @@ myOutfit();
 # --solutions--
 
 ```js
-var outerWear = "T-Shirt";
+const outerWear = "T-Shirt";
 function myOutfit() {
-  var outerWear = "sweater";
+  const outerWear = "sweater";
   return outerWear;
 }
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md
index 28bd619a55c..bc401dc1d74 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/golf-code.md
@@ -90,7 +90,8 @@ assert(golfScore(5, 9) === 'Go Home!');
 ## --seed-contents--
 
 ```js
-var names = ["Hole-in-one!", "Eagle", "Birdie", "Par", "Bogey", "Double Bogey", "Go Home!"];
+const names = ["Hole-in-one!", "Eagle", "Birdie", "Par", "Bogey", "Double Bogey", "Go Home!"];
+
 function golfScore(par, strokes) {
   // Only change code below this line
 
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md
index 21aa67e670c..16b4f4f56ff 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/increment-a-number-with-javascript.md
@@ -39,7 +39,7 @@ Você não deve usar o operador de atribuição.
 
 ```js
 assert(
-  /var\s*myVar\s*=\s*87;\s*\/*.*\s*([+]{2}\s*myVar|myVar\s*[+]{2});/.test(code)
+  /let\s*myVar\s*=\s*87;\s*\/*.*\s*([+]{2}\s*myVar|myVar\s*[+]{2});/.test(code)
 );
 ```
 
@@ -52,7 +52,7 @@ assert(/[+]{2}\s*myVar|myVar\s*[+]{2}/.test(code));
 Você não deve alterar o código acima do comentário especificado.
 
 ```js
-assert(/var myVar = 87;/.test(code));
+assert(/let myVar = 87;/.test(code));
 ```
 
 # --seed--
@@ -66,7 +66,7 @@ assert(/var myVar = 87;/.test(code));
 ## --seed-contents--
 
 ```js
-var myVar = 87;
+let myVar = 87;
 
 // Only change code below this line
 myVar = myVar + 1;
@@ -75,6 +75,6 @@ myVar = myVar + 1;
 # --solutions--
 
 ```js
-var myVar = 87;
+let myVar = 87;
 myVar++;
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md
index 7d594594680..874d3ed9a34 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/introducing-else-statements.md
@@ -64,7 +64,7 @@ assert(testElse(10) === 'Bigger than 5');
 Você não deve alterar o código acima ou abaixo dos comentários especificados.
 
 ```js
-assert(/var result = "";/.test(code) && /return result;/.test(code));
+assert(/let result = "";/.test(code) && /return result;/.test(code));
 ```
 
 # --seed--
@@ -73,7 +73,7 @@ assert(/var result = "";/.test(code) && /return result;/.test(code));
 
 ```js
 function testElse(val) {
-  var result = "";
+  let result = "";
   // Only change code below this line
 
   if (val > 5) {
@@ -95,7 +95,7 @@ testElse(4);
 
 ```js
 function testElse(val) {
-  var result = "";
+  let result = "";
   if(val > 5) {
     result = "Bigger than 5";
   } else {
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md
index a0d8ab56a24..4860c8cfdea 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md
@@ -12,8 +12,9 @@ dashedName: iterate-through-an-array-with-a-for-loop
 Uma tarefa comum em JavaScript é para iterar através do conteúdo de um array. Uma forma de fazer isso é com um laço `for`. Esse código vai exibir cada elemento do array `arr` no console:
 
 ```js
-var arr = [10, 9, 8, 7, 6];
-for (var i = 0; i < arr.length; i++) {
+const arr = [10, 9, 8, 7, 6];
+
+for (let i = 0; i < arr.length; i++) {
    console.log(arr[i]);
 }
 ```
@@ -62,18 +63,19 @@ assert(!__helpers.removeWhiteSpace(code).match(/total[=+-]0*[1-9]+/gm));
 
 ```js
 // Setup
-var myArr = [ 2, 3, 4, 5, 6];
+const myArr = [2, 3, 4, 5, 6];
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myArr = [ 2, 3, 4, 5, 6];
-var total = 0;
+const myArr = [2, 3, 4, 5, 6];
+let total = 0;
 
-for (var i = 0; i < myArr.length; i++) {
+for (let i = 0; i < myArr.length; i++) {
   total += myArr[i];
 }
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md
index a83f89c0b03..d1d0271330f 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-do...while-loops.md
@@ -12,8 +12,9 @@ dashedName: iterate-with-javascript-do---while-loops
 O próximo tipo de laço que você aprenderá é chamado de laço `do...while`. O laço `do...while` é chamado assim porque primeiro fará algo (`do`) ou executará algo uma vez dentro do bloco de código, não importando o que acontecer. Em seguida, continuará a executar o laço enquanto (`while`) a condição for `true`.
 
 ```js
-var ourArray = [];
-var i = 0;
+const ourArray = [];
+let i = 0;
+
 do {
   ourArray.push(i);
   i++;
@@ -23,8 +24,9 @@ do {
 O exemplo acima se comporta de forma similar a outros tipos de laços, e o array resultante se parecerá com `[0,1,2,3,4]`. No entanto, o que torna o laço `do...while` diferente de outros laços é como ele se comporta quando uma condição falha na primeira verificação. Vamos ver isso na prática: Aqui está um laço comum `while` que rodará o código no laço enquanto `i < 5`:
 
 ```js
-var ourArray = []; 
-var i = 5;
+const ourArray = []; 
+let i = 5;
+
 while (i < 5) {
   ourArray.push(i);
   i++;
@@ -34,8 +36,9 @@ while (i < 5) {
 Nesse exemplo, inicializamos o valor de `ourArray` como um array vazio e o valor de `i` sendo 5. Quando executamos o laço `while`, a condição é igual a `false` porque `i` não é menor que 5, portanto nós não executamos o código dentro do laço. O resultado é que `ourArray` terminará sem valores adicionados a ele, e ainda se parecerá com `[]` quando todas as linhas do código no exemplo acima forem completamente executadas. Agora, dê uma olhada no laço `do...while`:
 
 ```js
-var ourArray = []; 
-var i = 5;
+const ourArray = []; 
+let i = 5;
+
 do {
   ourArray.push(i);
   i++;
@@ -80,8 +83,8 @@ if(typeof myArray !== "undefined"){(function(){return myArray;})();}
 
 ```js
 // Setup
-var myArray = [];
-var i = 10;
+const myArray = [];
+let i = 10;
 
 // Only change code below this line
 while (i < 5) {
@@ -93,8 +96,8 @@ while (i < 5) {
 # --solutions--
 
 ```js
-var myArray = [];
-var i = 10;
+const myArray = [];
+let i = 10;
 do {
   myArray.push(i);
   i++;
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md
index 503ff928333..3b55efd09ce 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/local-scope-and-functions.md
@@ -15,9 +15,10 @@ Aqui está uma função `myTest` com uma variável local chamada `loc`.
 
 ```js
 function myTest() {
-  var loc = "foo";
+  const loc = "foo";
   console.log(loc);
 }
+
 myTest();
 console.log(loc);
 ```
@@ -38,6 +39,7 @@ O código não deve conter uma variável global `myVar`.
 function declared() {
   myVar;
 }
+
 assert.throws(declared, ReferenceError);
 ```
 
@@ -57,7 +59,6 @@ assert(
 
 ```js
 function myLocalScope() {
-
   // Only change code below this line
 
   console.log('inside myLocalScope', myVar);
@@ -73,9 +74,8 @@ console.log('outside myLocalScope', myVar);
 
 ```js
 function myLocalScope() {
-
   // Only change code below this line
-  var myVar;
+  let myVar;
   console.log('inside myLocalScope', myVar);
 }
 myLocalScope();
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md
index 3f21578117d..8db979418ed 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-push.md
@@ -16,10 +16,10 @@ Uma forma fácil de adicionar dados no final de um array é através da função
 Exemplos:
 
 ```js
-var arr1 = [1,2,3];
+const arr1 = [1, 2, 3];
 arr1.push(4);
 
-var arr2 = ["Stimpson", "J", "cat"];
+const arr2 = ["Stimpson", "J", "cat"];
 arr2.push(["happy", "joy"]);
 ```
 
@@ -64,14 +64,15 @@ assert(
 
 ```js
 // Setup
-var myArray = [["John", 23], ["cat", 2]];
+const myArray = [["John", 23], ["cat", 2]];
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myArray = [["John", 23], ["cat", 2]];
+const myArray = [["John", 23], ["cat", 2]];
 myArray.push(["dog",3]);
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md
index 592972f2114..3c7f958fc44 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.md
@@ -14,7 +14,7 @@ dashedName: manipulating-complex-objects
 Aqui está um exemplo de estrutura de dados complexas:
 
 ```js
-var ourMusic = [
+const ourMusic = [
   {
     "artist": "Daft Punk",
     "title": "Homework",
@@ -135,7 +135,7 @@ myMusic.forEach(object => {
 ## --seed-contents--
 
 ```js
-var myMusic = [
+const myMusic = [
   {
     "artist": "Billy Joel",
     "title": "Piano Man",
@@ -153,7 +153,7 @@ var myMusic = [
 # --solutions--
 
 ```js
-var myMusic = [
+const myMusic = [
   {
     "artist": "Billy Joel",
     "title": "Piano Man",
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md
index 2d725d17f71..b36c8a09da4 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/multiple-identical-options-in-switch-statements.md
@@ -12,7 +12,7 @@ dashedName: multiple-identical-options-in-switch-statements
 Se a instrução `break` for omitida de uma instrução `case` de um `switch`, as instruções `case` seguintes serão executadas até que seja encontrado um `break`. Se você tem várias entradas com a mesma saída, você pode representá-las em uma instrução `switch` da seguinte forma:
 
 ```js
-var result = "";
+let result = "";
 switch(val) {
   case 1:
   case 2:
@@ -109,7 +109,7 @@ assert(code.match(/case/g).length === 9);
 
 ```js
 function sequentialSizes(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
 
@@ -125,7 +125,7 @@ sequentialSizes(1);
 
 ```js
 function sequentialSizes(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case 1:
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md
index 6c77e1e2a0c..168604e8d19 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-decimals-with-javascript.md
@@ -42,11 +42,11 @@ assert(/\*/.test(code));
 ## --seed-contents--
 
 ```js
-var product = 2.0 * 0.0;
+const product = 2.0 * 0.0;
 ```
 
 # --solutions--
 
 ```js
-var product = 2.0 * 2.5;
+const product = 2.0 * 2.5;
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md
index f4c7329ff02..1260f4b802b 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/multiply-two-numbers-with-javascript.md
@@ -16,7 +16,7 @@ JavaScript usa o símbolo `*` para multiplicação de dois números.
 **Exemplo**
 
 ```js
-myVar = 13 * 13;
+const myVar = 13 * 13;
 ```
 
 `myVar` teria o valor `169`.
@@ -50,11 +50,11 @@ assert(/\*/.test(code));
 ## --seed-contents--
 
 ```js
-var product = 8 * 0;
+const product = 8 * 0;
 ```
 
 # --solutions--
 
 ```js
-var product = 8 * 10;
+const product = 8 * 10;
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md
index 1d70732ef8f..19d0687fe9a 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/nest-one-array-within-another-array.md
@@ -12,7 +12,7 @@ dashedName: nest-one-array-within-another-array
 Você também pode aninhar arrays dentro de outros arrays, como abaixo:
 
 ```js
-[["Bulls", 23], ["White Sox", 45]]
+const teams = [["Bulls", 23], ["White Sox", 45]];
 ```
 
 Isso é chamado um <dfn>array multidimensional</dfn>.
@@ -41,11 +41,11 @@ if(typeof myArray !== "undefined"){(function(){return myArray;})();}
 
 ```js
 // Only change code below this line
-var myArray = [];
+const myArray = [];
 ```
 
 # --solutions--
 
 ```js
-var myArray = [[1,2,3]];
+const myArray = [[1, 2, 3]];
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md
index 61b354601bc..dab980a96c4 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/profile-lookup.md
@@ -68,34 +68,33 @@ assert(lookUpProfile('Akira', 'address') === 'No such property');
 
 ```js
 // Setup
-var contacts = [
-    {
-        "firstName": "Akira",
-        "lastName": "Laine",
-        "number": "0543236543",
-        "likes": ["Pizza", "Coding", "Brownie Points"]
-    },
-    {
-        "firstName": "Harry",
-        "lastName": "Potter",
-        "number": "0994372684",
-        "likes": ["Hogwarts", "Magic", "Hagrid"]
-    },
-    {
-        "firstName": "Sherlock",
-        "lastName": "Holmes",
-        "number": "0487345643",
-        "likes": ["Intriguing Cases", "Violin"]
-    },
-    {
-        "firstName": "Kristian",
-        "lastName": "Vos",
-        "number": "unknown",
-        "likes": ["JavaScript", "Gaming", "Foxes"]
-    }
+const contacts = [
+  {
+    firstName: "Akira",
+    lastName: "Laine",
+    number: "0543236543",
+    likes: ["Pizza", "Coding", "Brownie Points"],
+  },
+  {
+    firstName: "Harry",
+    lastName: "Potter",
+    number: "0994372684",
+    likes: ["Hogwarts", "Magic", "Hagrid"],
+  },
+  {
+    firstName: "Sherlock",
+    lastName: "Holmes",
+    number: "0487345643",
+    likes: ["Intriguing Cases", "Violin"],
+  },
+  {
+    firstName: "Kristian",
+    lastName: "Vos",
+    number: "unknown",
+    likes: ["JavaScript", "Gaming", "Foxes"],
+  },
 ];
 
-
 function lookUpProfile(name, prop) {
   // Only change code below this line
 
@@ -108,44 +107,38 @@ lookUpProfile("Akira", "likes");
 # --solutions--
 
 ```js
-var contacts = [
-    {
-        "firstName": "Akira",
-        "lastName": "Laine",
-        "number": "0543236543",
-        "likes": ["Pizza", "Coding", "Brownie Points"]
-    },
-    {
-        "firstName": "Harry",
-        "lastName": "Potter",
-        "number": "0994372684",
-        "likes": ["Hogwarts", "Magic", "Hagrid"]
-    },
-    {
-        "firstName": "Sherlock",
-        "lastName": "Holmes",
-        "number": "0487345643",
-        "likes": ["Intriguing Cases", "Violin"]
-    },
-    {
-        "firstName": "Kristian",
-        "lastName": "Vos",
-        "number": "unknown",
-        "likes": ["JavaScript", "Gaming", "Foxes"]
-    },
+const contacts = [
+  {
+    firstName: "Akira",
+    lastName: "Laine",
+    number: "0543236543",
+    likes: ["Pizza", "Coding", "Brownie Points"],
+  },
+  {
+    firstName: "Harry",
+    lastName: "Potter",
+    number: "0994372684",
+    likes: ["Hogwarts", "Magic", "Hagrid"],
+  },
+  {
+    firstName: "Sherlock",
+    lastName: "Holmes",
+    number: "0487345643",
+    likes: ["Intriguing Cases", "Violin"],
+  },
+  {
+    firstName: "Kristian",
+    lastName: "Vos",
+    number: "unknown",
+    likes: ["JavaScript", "Gaming", "Foxes"],
+  },
 ];
-
-
-//Write your function in between these comments
-function lookUpProfile(name, prop){
-    for(var i in contacts){
-      if(contacts[i].firstName === name) {
-        return contacts[i][prop] || "No such property";
-      }
+function lookUpProfile(name, prop) {
+  for (let i in contacts) {
+    if (contacts[i].firstName === name) {
+      return contacts[i][prop] || "No such property";
     }
-   return "No such contact";
+  }
+  return "No such contact";
 }
-//Write your function in between these comments
-
-lookUpProfile("Akira", "likes");
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md
index 872ea6e039e..cbe779ce0b0 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/quoting-strings-with-single-quotes.md
@@ -12,21 +12,21 @@ dashedName: quoting-strings-with-single-quotes
 Valores de <dfn>string</dfn> em JavaScript podem ser escritas com aspas simples ou duplas, desde que você comece e termine com o mesmo tipo de aspas. Diferente de outras linguagens de programação, aspas simples e duplas funcionam da mesma forma em JavaScript.
 
 ```js
-doubleQuoteStr = "This is a string"; 
-singleQuoteStr = 'This is also a string';
+const doubleQuoteStr = "This is a string"; 
+const singleQuoteStr = 'This is also a string';
 ```
 
 O motivo pelo qual você pode querer usar um tipo de aspas no lugar da outra é se você vir a querer usar ambas em uma string. Isso pode acontecer se você quiser salvar uma conversa em uma string e ter a conversa entre aspas. Outro uso para isso seria salvar uma tag `<a>` com vários atributos em aspas, tudo dentro de uma string.
 
 ```js
-conversation = 'Finn exclaims to Jake, "Algebraic!"';
+const conversation = 'Finn exclaims to Jake, "Algebraic!"';
 ```
 
 Porém, isso se torna um problema se você precisar usar as aspas mais extremas dentro dela. Lembre-se, uma string tem o mesmo tipo de aspas no início e no final. Mas se você tem aquela mesma aspa em algum lugar no meio, a string vai terminar mais cedo e lançará um erro.
 
 ```js
-goodStr = 'Jake asks Finn, "Hey, let\'s go on an adventure?"'; 
-badStr = 'Finn responds, "Let's go!"';
+const goodStr = 'Jake asks Finn, "Hey, let\'s go on an adventure?"'; 
+const badStr = 'Finn responds, "Let's go!"';
 ```
 
 Aqui `badStr` lançará um erro.
@@ -71,11 +71,11 @@ assert(code.match(/"/g).length === 4 && code.match(/'/g).length === 2);
 ## --seed-contents--
 
 ```js
-var myStr = "<a href=\"http://www.example.com\" target=\"_blank\">Link</a>";
+const myStr = "<a href=\"http://www.example.com\" target=\"_blank\">Link</a>";
 ```
 
 # --solutions--
 
 ```js
-var myStr = '<a href="http://www.example.com" target="_blank">Link</a>';
+const myStr = '<a href="http://www.example.com" target="_blank">Link</a>';
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md
index 256e6325f7f..bec11f1f664 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/record-collection.md
@@ -115,7 +115,7 @@ const _recordCollection = {
 
 ```js
 // Setup
-var recordCollection = {
+const recordCollection = {
   2548: {
     albumTitle: 'Slippery When Wet',
     artist: 'Bon Jovi',
@@ -146,7 +146,7 @@ updateRecords(recordCollection, 5439, 'artist', 'ABBA');
 # --solutions--
 
 ```js
-var recordCollection = {
+const recordCollection = {
   2548: {
     albumTitle: 'Slippery When Wet',
     artist: 'Bon Jovi',
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md
index 4dfb3c5a333..c15779f5e04 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion.md
@@ -14,9 +14,9 @@ Recursão é o conceito de que uma função pode ser chamada por ela mesma. Para
 
 ```js
   function multiply(arr, n) {
-    var product = 1;
-    for (var i = 0; i < n; i++) {
-        product *= arr[i];
+    let product = 1;
+    for (let i = 0; i < n; i++) {
+      product *= arr[i];
     }
     return product;
   }
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md
index 3d3f58f14ee..c08b94c7c65 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/replacing-if-else-chains-with-switch.md
@@ -108,7 +108,7 @@ assert(chainToSwitch(156) === '');
 
 ```js
 function chainToSwitch(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
   if (val === "bob") {
@@ -134,7 +134,7 @@ chainToSwitch(7);
 
 ```js
 function chainToSwitch(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case "bob":
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md
index 6015e339808..b084ca43d88 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/return-a-value-from-a-function-with-return.md
@@ -17,7 +17,8 @@ Nós podemos passar valores para uma função com <dfn>argumentos</dfn>. Você p
 function plusThree(num) {
   return num + 3;
 }
-var answer = plusThree(5);
+
+const answer = plusThree(5);
 ```
 
 `answer` tem o valor de `8`.
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md
index 13e07afff8a..82c837dbda5 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/selecting-from-many-options-with-switch-statements.md
@@ -78,7 +78,7 @@ assert(code.match(/break/g).length > 2);
 
 ```js
 function caseInSwitch(val) {
-  var answer = "";
+  let answer = "";
   // Only change code below this line
 
 
@@ -94,7 +94,7 @@ caseInSwitch(1);
 
 ```js
 function caseInSwitch(val) {
-  var answer = "";
+  let answer = "";
 
   switch(val) {
     case 1:
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md
index 9c108ac14dc..9b7bfd86ef7 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/shopping-list.md
@@ -81,13 +81,13 @@ var hasNumber = false;
 ## --seed-contents--
 
 ```js
-var myList = [];
+const myList = [];
 ```
 
 # --solutions--
 
 ```js
-var myList = [
+const myList = [
   ["Candy", 10],
   ["Potatoes", 12],
   ["Eggs", 12],
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md
index ff6f79a9c77..ed2c4506254 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/stand-in-line.md
@@ -93,12 +93,10 @@ function nextInLine(arr, item) {
 
   return item;
   // Only change code above this line
-
-
 }
 
 // Setup
-var testArr = [1,2,3,4,5];
+const testArr = [1, 2, 3, 4, 5];
 
 // Display code
 console.log("Before: " + JSON.stringify(testArr));
@@ -109,7 +107,7 @@ console.log("After: " + JSON.stringify(testArr));
 # --solutions--
 
 ```js
-var testArr = [ 1,2,3,4,5];
+const testArr = [1, 2, 3, 4, 5];
 
 function nextInLine(arr, item) {
     arr.push(item);
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md
index 079b028a3ee..07196097e64 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/store-multiple-values-in-one-variable-using-javascript-arrays.md
@@ -14,7 +14,7 @@ Com as variáveis de `array` em JavaScript, podemos armazenar diversos dados em
 Você começa uma declaração de um array com a abertura de um colchetes, terminando com o fechamento do colchetes e colocando vírgulas entre cada entrada, dessa forma:
 
 ```js
-var sandwich = ["peanut butter", "jelly", "bread"]
+const sandwich = ["peanut butter", "jelly", "bread"];
 ```
 
 # --instructions--
@@ -53,11 +53,11 @@ assert(typeof myArray[1] !== 'undefined' && typeof myArray[1] == 'number');
 
 ```js
 // Only change code below this line
-var myArray = [];
+const myArray = [];
 ```
 
 # --solutions--
 
 ```js
-var myArray = ["The Answer", 42];
+const myArray = ["The Answer", 42];
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md
index 763f26cb6ca..33106767882 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/subtract-one-number-from-another-with-javascript.md
@@ -16,7 +16,7 @@ JavaScript usa o símbolo `-` para subtração.
 **Exemplo**
 
 ```js
-myVar = 12 - 6;
+const myVar = 12 - 6;
 ```
 
 `myVar` teria o valor `6`.
@@ -49,11 +49,11 @@ assert(/difference=45-33;?/.test(__helpers.removeWhiteSpace(code)));
 ## --seed-contents--
 
 ```js
-var difference = 45 - 0;
+const difference = 45 - 0;
 ```
 
 # --solutions--
 
 ```js
-var difference = 45 - 33;
+const difference = 45 - 33;
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md
index 27ed80eec0d..2c8af2b05e4 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md
@@ -13,10 +13,11 @@ dashedName: testing-objects-for-properties
 **Exemplo**
 
 ```js
-var myObj = {
+const myObj = {
   top: "hat",
   bottom: "pants"
 };
+
 myObj.hasOwnProperty("top");
 myObj.hasOwnProperty("middle");
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md
index 58b01d3748c..0ad2fe93dc2 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/understand-string-immutability.md
@@ -14,14 +14,14 @@ Em JavaScript, valores `String` são <dfn>imutáveis</dfn>, o que significa que
 Por exemplo, o código a seguir:
 
 ```js
-var myStr = "Bob";
+let myStr = "Bob";
 myStr[0] = "J";
 ```
 
 não permite alterar o valor de `myStr` para `Job`, porque o conteúdo de `myStr` não pode ser alterado. Note que isso *não* significa que `myStr` não pode ser alterado, apenas que os caracteres individuais de uma <dfn>string literal</dfn> não podem ser alterados. A única forma de alterar `myStr` seria atribuindo a ela uma nova string, dessa forma:
 
 ```js
-var myStr = "Bob";
+let myStr = "Bob";
 myStr = "Job";
 ```
 
@@ -55,7 +55,7 @@ assert(/myStr = "Jello World"/.test(code));
 
 ```js
 // Setup
-var myStr = "Jello World";
+let myStr = "Jello World";
 
 // Only change code below this line
 myStr[0] = "H"; // Change this line
@@ -65,6 +65,6 @@ myStr[0] = "H"; // Change this line
 # --solutions--
 
 ```js
-var myStr = "Jello World";
+let myStr = "Jello World";
 myStr = "Hello World";
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md
index d1240f035f4..0d45f0d6a32 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-boolean-values.md
@@ -43,7 +43,6 @@ welcomeToBooleans();
 
 ```js
 function welcomeToBooleans() {
-
   // Only change code below this line
 
   return false; // Change this line
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md
index 5c0ee20a1b6..3230b281fe5 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/understanding-undefined-value-returned-from-a-function.md
@@ -14,10 +14,12 @@ Uma função pode incluir a instrução `return` mas ela não precisa fazer isso
 **Exemplo**
 
 ```js
-var sum = 0;
+let sum = 0;
+
 function addSum(num) {
   sum = sum + num;
 }
+
 addSum(3);
 ```
 
@@ -61,7 +63,7 @@ assert(
 
 ```js
 // Setup
-var sum = 0;
+let sum = 0;
 
 function addThree() {
   sum = sum + 3;
@@ -79,7 +81,7 @@ addFive();
 # --solutions--
 
 ```js
-var sum = 0;
+let sum = 0;
 
 function addThree() {
   sum = sum + 3;
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md
index fcf5f4f160a..27e558a6bf1 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/updating-object-properties.md
@@ -14,7 +14,7 @@ Depois de criar um objeto JavaScript, você pode atualizar suas propriedades a q
 Por exemplo, vamos dar uma olhada em `ourDog`:
 
 ```js
-var ourDog = {
+const ourDog = {
   "name": "Camper",
   "legs": 4,
   "tails": 1,
@@ -54,7 +54,7 @@ assert(/"name": "Coder"/.test(code));
 
 ```js
 // Setup
-var myDog = {
+const myDog = {
   "name": "Coder",
   "legs": 4,
   "tails": 1,
@@ -62,12 +62,13 @@ var myDog = {
 };
 
 // Only change code below this line
+
 ```
 
 # --solutions--
 
 ```js
-var myDog = {
+const myDog = {
   "name": "Coder",
   "legs": 4,
   "tails": 1,
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md
index 49ac1295773..5b7d55bc900 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/use-bracket-notation-to-find-the-nth-character-in-a-string.md
@@ -16,8 +16,8 @@ Lembre-se de que computadores começam contando do `0`. Então, o primeiro carac
 Exemplo:
 
 ```js
-var firstName = "Ada";
-var secondLetterOfFirstName = firstName[1];
+const firstName = "Ada";
+const secondLetterOfFirstName = firstName[1];
 ```
 
 `secondLetterOfFirstName` teria o valor da string `d`.
@@ -54,15 +54,15 @@ assert(code.match(/thirdLetterOfLastName\s*?=\s*?lastName\[.*?\]/));
 
 ```js
 // Setup
-var lastName = "Lovelace";
+const lastName = "Lovelace";
 
 // Only change code below this line
-var thirdLetterOfLastName = lastName; // Change this line
+const thirdLetterOfLastName = lastName; // Change this line
 ```
 
 # --solutions--
 
 ```js
-var lastName = "Lovelace";
-var thirdLetterOfLastName = lastName[2];
+const lastName = "Lovelace";
+const thirdLetterOfLastName = lastName[2];
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md
index 8d4f0948e24..bea00af7483 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-range-of-numbers.md
@@ -73,7 +73,7 @@ function rangeOfNumbers(startNum, endNum) {
   if (endNum - startNum === 0) {
     return [startNum];
   } else {
-    var numbers = rangeOfNumbers(startNum, endNum - 1);
+    const numbers = rangeOfNumbers(startNum, endNum - 1);
     numbers.push(endNum);
     return numbers;
   }
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md
index 81bd81106ab..0ff735c10d9 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix.md
@@ -20,7 +20,7 @@ parseInt(string, radix);
 Exemplo:
 
 ```js
-var a = parseInt("11", 2);
+const a = parseInt("11", 2);
 ```
 
 A variável radix diz que `11` está no sistema binário, ou base 2. Esse exemplo converte a string `11` para um inteiro `3`.
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md
index a48ab989379..6cad3010f54 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function.md
@@ -12,7 +12,7 @@ dashedName: use-the-parseint-function
 A função `parseInt()` analisa uma string e retorna um inteiro. Exemplo:
 
 ```js
-var a = parseInt("007");
+const a = parseInt("007");
 ```
 
 A função acima converte a string `007` para o inteiro `7`. Se o primeiro caractere na string não pode ser convertido em um número, então ele retorna `NaN`.
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md
index 6137d6f5286..973e9af6f3f 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md
@@ -14,7 +14,7 @@ Objetos podem ser pensados como armazenamento de chave/valor, como um dicionári
 Aqui está um exemplo de uma simples pesquisa reversa no alfabeto:
 
 ```js
-var alpha = {
+const alpha = {
   1:"Z",
   2:"Y",
   3:"X",
@@ -24,10 +24,11 @@ var alpha = {
   25:"B",
   26:"A"
 };
+
 alpha[2];
 alpha[24];
 
-var value = 2;
+const value = 2;
 alpha[value];
 ```
 
@@ -102,7 +103,7 @@ assert(
 ```js
 // Setup
 function phoneticLookup(val) {
-  var result = "";
+  let result = "";
 
   // Only change code below this line
   switch(val) {
@@ -136,9 +137,9 @@ phoneticLookup("charlie");
 
 ```js
 function phoneticLookup(val) {
-  var result = "";
+  let result = "";
 
-  var lookup = {
+  const lookup = {
     alpha: "Adams",
     bravo: "Boston",
     charlie: "Chicago",
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md
index 19f327e8afd..4b28d911f64 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/basic-javascript/word-blanks.md
@@ -16,7 +16,7 @@ Em um jogo de "Mad Libs", você recebe frases com algumas palavras faltando, com
 Considere a frase - Era realmente **\_\_\_\_** e nós **\_\_\_\_** nós mesmos **\_\_\_\_**. Essa frase possui três pedaços faltando - um adjetivo, um verbo e um advérbio, e nós podemos adicionar palavras de nossa escolha para completar. Em seguida, podemos atribuir a frase completa para uma variável como se segue:
 
 ```js
-var sentence = "It was really " + "hot" + ", and we " + "laughed" + " ourselves " + "silly" + ".";
+const sentence = "It was really " + "hot" + ", and we " + "laughed" + " ourselves " + "silly" + ".";
 ```
 
 # --instructions--
@@ -84,24 +84,24 @@ const removeAssignments = str => str
 ## --seed-contents--
 
 ```js
-var myNoun = "dog";
-var myAdjective = "big";
-var myVerb = "ran";
-var myAdverb = "quickly";
+const myNoun = "dog";
+const myAdjective = "big";
+const myVerb = "ran";
+const myAdverb = "quickly";
 
 // Only change code below this line
-var wordBlanks = ""; // Change this line
+const wordBlanks = ""; // Change this line
 // Only change code above this line
 ```
 
 # --solutions--
 
 ```js
-var myNoun = "dog";
-var myAdjective = "big";
-var myVerb = "ran";
-var myAdverb = "quickly";
+const myNoun = "dog";
+const myAdjective = "big";
+const myVerb = "ran";
+const myAdverb = "quickly";
 
-var wordBlanks = "Once there was a " + myNoun + " which was very " + myAdjective + ". ";
+let wordBlanks = "Once there was a " + myNoun + " which was very " + myAdjective + ". ";
 wordBlanks += "It " + myVerb + " " + myAdverb + " around the yard.";
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md
index 74ca32bb5af..3cab9700120 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/add-elements-to-the-end-of-an-array-using-concat-instead-of-push.md
@@ -13,7 +13,7 @@ Programação funcional é basicamente criar e utilizar funções que não modif
 O último desafio mostrou como usar o método `concat` para criar um novo array a partir da combinação de outros sem modificar os originais. Compare os métodos `concat` e `push`. O `push` adiciona um item ao final do array à esquerda do `.`. Ele modifica o array. Exemplo:
 
 ```js
-var arr = [1, 2, 3];
+const arr = [1, 2, 3];
 arr.push([4, 5, 6]);
 ```
 
@@ -71,8 +71,9 @@ function nonMutatingPush(original, newItem) {
 
   // Only change code above this line
 }
-var first = [1, 2, 3];
-var second = [4, 5];
+
+const first = [1, 2, 3];
+const second = [4, 5];
 nonMutatingPush(first, second);
 ```
 
@@ -82,7 +83,6 @@ nonMutatingPush(first, second);
 function nonMutatingPush(original, newItem) {
   return original.concat(newItem);
 }
-var first = [1, 2, 3];
-var second = [4, 5];
-nonMutatingPush(first, second);
+const first = [1, 2, 3];
+const second = [4, 5];
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md
index 95d7bb6c98b..83daf616139 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/apply-functional-programming-to-convert-strings-to-url-slugs.md
@@ -77,7 +77,6 @@ function urlSlug(title) {
 # --solutions--
 
 ```js
-// Only change code below this line
 function urlSlug(title) {
   return title.trim().split(/\s+/).join("-").toLowerCase();
 }
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md
index c7cef37d22d..91fa5370882 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/avoid-mutations-and-side-effects-using-functional-programming.md
@@ -57,9 +57,9 @@ A função `incrementer` deve retornar um valor baseado no valor da variável gl
 
 ```js
 // The global variable
-var fixedValue = 4;
+let fixedValue = 4;
 
-function incrementer () {
+function incrementer() {
   // Only change code below this line
 
 
@@ -70,7 +70,7 @@ function incrementer () {
 # --solutions--
 
 ```js
-var fixedValue = 4
+let fixedValue = 4
 
 function incrementer() {
   return fixedValue + 1
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md
index a0f78252720..d44460fcffc 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/combine-an-array-into-a-string-using-the-join-method.md
@@ -13,8 +13,8 @@ O método `join` é usado para juntar os elementos de um array, resultando em um
 Exemplo:
 
 ```js
-var arr = ["Hello", "World"];
-var str = arr.join(" ");
+const arr = ["Hello", "World"];
+const str = arr.join(" ");
 ```
 
 O valor de `str` é `Hello World`.
@@ -76,6 +76,7 @@ function sentensify(str) {
 
   // Only change code above this line
 }
+
 sentensify("May-the-force-be-with-you");
 ```
 
@@ -83,8 +84,6 @@ sentensify("May-the-force-be-with-you");
 
 ```js
 function sentensify(str) {
-  // Only change code below this line
   return str.split(/\W/).join(' ');
-  // Only change code above this line
 }
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md
index 5f2e3f0ec3b..fe25f4f3fde 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/combine-two-arrays-using-the-concat-method.md
@@ -60,8 +60,9 @@ function nonMutatingConcat(original, attach) {
 
   // Only change code above this line
 }
-var first = [1, 2, 3];
-var second = [4, 5];
+
+const first = [1, 2, 3];
+const second = [4, 5];
 nonMutatingConcat(first, second);
 ```
 
@@ -69,11 +70,8 @@ nonMutatingConcat(first, second);
 
 ```js
 function nonMutatingConcat(original, attach) {
-  // Only change code below this line
   return original.concat(attach);
-  // Only change code above this line
 }
-var first = [1, 2, 3];
-var second = [4, 5];
-nonMutatingConcat(first, second);
+const first = [1, 2, 3];
+const second = [4, 5];
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md
index 9b054777b8d..4bfd307fff4 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md
@@ -38,17 +38,17 @@ assert(!code.match(/\.?[\s\S]*?map/g));
 
 ```js
 // The global variable
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myMap = function(callback) {
-  var newArray = [];
+  const newArray = [];
   // Only change code below this line
 
   // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myMap(function(item) {
+const new_s = s.myMap(function(item) {
   return item * 2;
 });
 ```
@@ -56,20 +56,17 @@ var new_s = s.myMap(function(item) {
 # --solutions--
 
 ```js
-// the global Array
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myMap = function(callback) {
-  var newArray = [];
-  // Only change code below this line
-  for (var elem of this) {
+  const newArray = [];
+  for (const elem of this) {
     newArray.push(callback(elem));
   }
-  // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myMap(function(item) {
+const new_s = s.myMap(function(item) {
   return item * 2;
 });
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md
index 5936d428777..96fa45b4f6e 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/implement-the-filter-method-on-a-prototype.md
@@ -34,16 +34,16 @@ assert(!code.match(/\.?[\s\S]*?filter/g));
 
 ```js
 // The global variable
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myFilter = function(callback) {
   // Only change code below this line
-  var newArray = [];
+  const newArray = [];
   // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myFilter(function(item) {
+const new_s = s.myFilter(function(item) {
   return item % 2 === 1;
 });
 ```
@@ -51,20 +51,17 @@ var new_s = s.myFilter(function(item) {
 # --solutions--
 
 ```js
-// the global Array
-var s = [23, 65, 98, 5];
+const s = [23, 65, 98, 5];
 
 Array.prototype.myFilter = function(callback) {
-  var newArray = [];
-  // Only change code below this line
+  const newArray = [];
   for (let i = 0; i < this.length; i++) {
     if (callback(this[i])) newArray.push(this[i]);
   }
-  // Only change code above this line
   return newArray;
 };
 
-var new_s = s.myFilter(function(item) {
+const new_s = s.myFilter(function(item) {
   return item % 2 === 1;
 });
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md
index f395576c8f9..26826046c7f 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/introduction-to-currying-and-partial-application.md
@@ -35,7 +35,7 @@ curried(1)(2)
 Isso é útil em seu programa quando você não pode fornecer todos os argumentos para uma função de uma só vez. Você pode salvar cada chamada de função em uma variável, que será uma referência à função retornada que recebe o próximo argumento quando ele estiver disponível. Um exemplo usando a função do exemplo acima:
 
 ```js
-var funcForY = curried(1);
+const funcForY = curried(1);
 console.log(funcForY(2)); // 3
 ```
 
@@ -45,7 +45,8 @@ Da mesma forma, <dfn>aplicação parcial</dfn> pode ser descrita como a aplicaç
 function impartial(x, y, z) {
   return x + y + z;
 }
-var partialFn = impartial.bind(this, 1, 2);
+
+const partialFn = impartial.bind(this, 1, 2);
 partialFn(10); // 13
 ```
 
@@ -90,6 +91,7 @@ function add(x) {
 
   // Only change code above this line
 }
+
 add(10)(20)(30);
 ```
 
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md
index 8ff1c00492d..573bc8acb0c 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/pass-arguments-to-avoid-external-dependence-in-a-function.md
@@ -53,10 +53,10 @@ assert(__newValue === 5);
 
 ```js
 // The global variable
-var fixedValue = 4;
+let fixedValue = 4;
 
 // Only change code below this line
-function incrementer () {
+function incrementer() {
 
 
   // Only change code above this line
@@ -66,15 +66,9 @@ function incrementer () {
 # --solutions--
 
 ```js
-// The global variable
-var fixedValue = 4;
+let fixedValue = 4;
 
-// Only change code below this line
-function incrementer (fixedValue) {
+function incrementer(fixedValue) {
   return fixedValue + 1;
-
-  // Only change code above this line
 }
-
-
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md
index add31589006..54d0a2f3e49 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/remove-elements-from-an-array-using-slice-instead-of-splice.md
@@ -11,7 +11,7 @@ dashedName: remove-elements-from-an-array-using-slice-instead-of-splice
 É comum precisar remover alguns itens de um array e manter o resto. O JavaScript oferece o método `splice`, que recebe uma posição de onde começar a remover e o número de elementos para remover como argumentos para isso. Se o segundo argumento for omitido, o padrão é remover todos os itens até o final. No entanto, o método `splice` modifica o array original em que é chamado. Exemplo:
 
 ```js
-var cities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
+const cities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
 cities.splice(3, 1);
 ```
 
@@ -69,7 +69,8 @@ function nonMutatingSplice(cities) {
 
   // Only change code above this line
 }
-var inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
+
+const inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
 nonMutatingSplice(inputCities);
 ```
 
@@ -77,10 +78,7 @@ nonMutatingSplice(inputCities);
 
 ```js
 function nonMutatingSplice(cities) {
-  // Only change code below this line
   return cities.slice(0,3);
-  // Only change code above this line
 }
-var inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
-nonMutatingSplice(inputCities);
+const inputCities = ["Chicago", "Delhi", "Islamabad", "London", "Berlin"];
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md
index 54bcac4eb57..6d520e4dc7d 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array.md
@@ -68,24 +68,23 @@ assert(JSON.stringify(nonMutatingSort([140000, 104, 99])) ===
 ## --seed-contents--
 
 ```js
-var globalArray = [5, 6, 3, 2, 9];
+const globalArray = [5, 6, 3, 2, 9];
+
 function nonMutatingSort(arr) {
   // Only change code below this line
 
 
   // Only change code above this line
 }
+
 nonMutatingSort(globalArray);
 ```
 
 # --solutions--
 
 ```js
-var globalArray = [5, 6, 3, 2, 9];
+const globalArray = [5, 6, 3, 2, 9];
 function nonMutatingSort(arr) {
-  // Only change code below this line
   return [].concat(arr).sort((a,b) => a-b);
-  // Only change code above this line
 }
-nonMutatingSort(globalArray);
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md
index 79e0a6cfe5b..884d555ac4d 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/return-part-of-an-array-using-the-slice-method.md
@@ -13,8 +13,8 @@ O método `slice` retorna uma fatia de elementos de um array. Ele pode receber d
 Exemplo:
 
 ```js
-var arr = ["Cat", "Dog", "Tiger", "Zebra"];
-var newArray = arr.slice(1, 3);
+const arr = ["Cat", "Dog", "Tiger", "Zebra"];
+const newArray = arr.slice(1, 3);
 ```
 
 `newArray` terá o valor `["Dog", "Tiger"]`.
@@ -78,7 +78,8 @@ function sliceArray(anim, beginSlice, endSlice) {
 
   // Only change code above this line
 }
-var inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
+
+const inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
 sliceArray(inputAnim, 1, 3);
 ```
 
@@ -86,10 +87,7 @@ sliceArray(inputAnim, 1, 3);
 
 ```js
 function sliceArray(anim, beginSlice, endSlice) {
-  // Only change code below this line
-  return anim.slice(beginSlice, endSlice)
-  // Only change code above this line
+  return anim.slice(beginSlice, endSlice);
 }
-var inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
-sliceArray(inputAnim, 1, 3);
+const inputAnim = ["Cat", "Dog", "Tiger", "Zebra", "Ant"];
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md
index 6e733a5bcbe..33c39df3bbb 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/sort-an-array-alphabetically-using-the-sort-method.md
@@ -18,6 +18,7 @@ function ascendingOrder(arr) {
     return a - b;
   });
 }
+
 ascendingOrder([1, 5, 2, 3, 4]);
 ```
 
@@ -29,6 +30,7 @@ function reverseAlpha(arr) {
     return a === b ? 0 : a < b ? 1 : -1;
   });
 }
+
 reverseAlpha(['l', 'h', 'z', 'b', 's']);
 ```
 
@@ -86,6 +88,7 @@ function alphabeticalOrder(arr) {
   return arr
   // Only change code above this line
 }
+
 alphabeticalOrder(["a", "d", "c", "a", "z", "g"]);
 ```
 
@@ -93,9 +96,6 @@ alphabeticalOrder(["a", "d", "c", "a", "z", "g"]);
 
 ```js
 function alphabeticalOrder(arr) {
-  // Only change code below this line
   return arr.sort();
-  // Only change code above this line
 }
-alphabeticalOrder(["a", "d", "c", "a", "z", "g"]);
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md
index 12ff08ab86b..b0c70d668dc 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/split-a-string-into-an-array-using-the-split-method.md
@@ -13,11 +13,11 @@ O método `split` divide uma string em um array de strings. Ela recebe um delimi
 Abaixo há dois exemplos de uso de split, um separando uma string por espaços, e outro por dígitos usando uma expressão regular:
 
 ```js
-var str = "Hello World";
-var bySpace = str.split(" ");
+const str = "Hello World";
+const bySpace = str.split(" ");
 
-var otherString = "How9are7you2today";
-var byDigits = otherString.split(/\d/);
+const otherString = "How9are7you2today";
+const byDigits = otherString.split(/\d/);
 ```
 
 `bySpace` terá o valor `["Hello", "World"]` e `byDigits` terá o valor `["How", "are", "you", "today"]`.
@@ -74,6 +74,7 @@ function splitify(str) {
 
   // Only change code above this line
 }
+
 splitify("Hello World,I-am code");
 ```
 
@@ -81,8 +82,6 @@ splitify("Hello World,I-am code");
 
 ```js
 function splitify(str) {
-  // Only change code below this line
   return str.split(/\W/);
-  // Only change code above this line
 }
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md
index 6504a860f3b..9f5a8d1c365 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/understand-the-hazards-of-using-imperative-code.md
@@ -59,29 +59,29 @@ assert.deepEqual(finalTabs.tabs, [
 
 ```js
 // tabs is an array of titles of each site open within the window
-var Window = function(tabs) {
+const Window = function(tabs) {
   this.tabs = tabs; // We keep a record of the array inside the object
 };
 
 // When you join two windows into one window
-Window.prototype.join = function (otherWindow) {
+Window.prototype.join = function(otherWindow) {
   this.tabs = this.tabs.concat(otherWindow.tabs);
   return this;
 };
 
 // When you open a new tab at the end
-Window.prototype.tabOpen = function (tab) {
+Window.prototype.tabOpen = function(tab) {
   this.tabs.push('new tab'); // Let's open a new tab for now
   return this;
 };
 
 // When you close a tab
-Window.prototype.tabClose = function (index) {
+Window.prototype.tabClose = function(index) {
 
   // Only change code below this line
 
-  var tabsBeforeIndex = this.tabs.splice(0, index); // Get the tabs before the tab
-  var tabsAfterIndex = this.tabs.splice(index + 1); // Get the tabs after the tab
+  const tabsBeforeIndex = this.tabs.splice(0, index); // Get the tabs before the tab
+  const tabsAfterIndex = this.tabs.splice(index + 1); // Get the tabs after the tab
 
   this.tabs = tabsBeforeIndex.concat(tabsAfterIndex); // Join them together
 
@@ -91,12 +91,12 @@ Window.prototype.tabClose = function (index) {
  };
 
 // Let's create three browser windows
-var workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']); // Your mailbox, drive, and other work sites
-var socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']); // Social sites
-var videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']); // Entertainment sites
+const workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']); // Your mailbox, drive, and other work sites
+const socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']); // Social sites
+const videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']); // Entertainment sites
 
 // Now perform the tab opening, closing, and other operations
-var finalTabs = socialWindow
+const finalTabs = socialWindow
   .tabOpen() // Open a new tab for cat memes
   .join(videoWindow.tabClose(2)) // Close third tab in video window, and join
   .join(workWindow.tabClose(1).tabOpen());
@@ -106,40 +106,34 @@ console.log(finalTabs.tabs);
 # --solutions--
 
 ```js
-// tabs is an array of titles of each site open within the window
-var Window = function(tabs) {
-  this.tabs = tabs; // We keep a record of the array inside the object
+const Window = function(tabs) {
+  this.tabs = tabs;
 };
 
-// When you join two windows into one window
-Window.prototype.join = function (otherWindow) {
+Window.prototype.join = function(otherWindow) {
   this.tabs = this.tabs.concat(otherWindow.tabs);
   return this;
 };
 
-// When you open a new tab at the end
-Window.prototype.tabOpen = function (tab) {
-  this.tabs.push('new tab'); // Let's open a new tab for now
+Window.prototype.tabOpen = function(tab) {
+  this.tabs.push('new tab');
   return this;
 };
 
-// When you close a tab
-Window.prototype.tabClose = function (index) {
-  var tabsBeforeIndex = this.tabs.slice(0, index); // Get the tabs before the tab
-  var tabsAfterIndex = this.tabs.slice(index + 1); // Get the tabs after the tab
+Window.prototype.tabClose = function(index) {
+  const tabsBeforeIndex = this.tabs.slice(0, index);
+  const tabsAfterIndex = this.tabs.slice(index + 1);
 
-  this.tabs = tabsBeforeIndex.concat(tabsAfterIndex); // Join them together
+  this.tabs = tabsBeforeIndex.concat(tabsAfterIndex);
   return this;
  };
 
-// Let's create three browser windows
-var workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']); // Your mailbox, drive, and other work sites
-var socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']); // Social sites
-var videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']); //  Entertainment sites
+const workWindow = new Window(['GMail', 'Inbox', 'Work mail', 'Docs', 'freeCodeCamp']);
+const socialWindow = new Window(['FB', 'Gitter', 'Reddit', 'Twitter', 'Medium']);
+const videoWindow = new Window(['Netflix', 'YouTube', 'Vimeo', 'Vine']);
 
-// Now perform the tab opening, closing, and other operations
-var finalTabs = socialWindow
-  .tabOpen() // Open a new tab for cat memes
-  .join(videoWindow.tabClose(2)) // Close third tab in video window, and join
+const finalTabs = socialWindow
+  .tabOpen()
+  .join(videoWindow.tabClose(2))
   .join(workWindow.tabClose(1).tabOpen());
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md
index e4582ceaf8c..e060ee8e5d0 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-every-method-to-check-that-every-element-in-an-array-meets-a-criteria.md
@@ -13,7 +13,8 @@ O método `every` funciona verificando se *todos* os elementos de um array passa
 Por exemplo, o código a seguir verifica se todos os elementos no array `numbers` são menores que 10:
 
 ```js
-var numbers = [1, 5, 8, 0, 10, 11];
+const numbers = [1, 5, 8, 0, 10, 11];
+
 numbers.every(function(currentValue) {
   return currentValue < 10;
 });
@@ -62,6 +63,7 @@ function checkPositive(arr) {
 
   // Only change code above this line
 }
+
 checkPositive([1, 2, 3, -4, 5]);
 ```
 
@@ -69,9 +71,6 @@ checkPositive([1, 2, 3, -4, 5]);
 
 ```js
 function checkPositive(arr) {
-  // Only change code below this line
   return arr.every(num => num > 0);
-  // Only change code above this line
 }
-checkPositive([1, 2, 3, -4, 5]);
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md
index 4b3fbd73b73..7ad02577d71 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-reduce-method-to-analyze-data.md
@@ -93,7 +93,7 @@ assert(getRating(watchList.filter((_, i) => i < 1 || i > 2)) === 8.55);
 
 ```js
 // The global variable
-var watchList = [
+const watchList = [
   {
     "Title": "Inception",
     "Year": "2010",
@@ -206,22 +206,22 @@ var watchList = [
   }
 ];
 
-function getRating(watchList){
+function getRating(watchList) {
   // Only change code below this line
-  var averageRating;
+  let averageRating;
 
 
   // Only change code above this line
   return averageRating;
 }
+
 console.log(getRating(watchList));
 ```
 
 # --solutions--
 
 ```js
-// The global variable
-var watchList = [
+const watchList = [
   {
     "Title": "Inception",
     "Year": "2010",
@@ -334,8 +334,8 @@ var watchList = [
   }
 ];
 
-function getRating(watchList){
-  var averageRating;
+function getRating(watchList) {
+  let averageRating;
   const rating = watchList
     .filter(obj => obj.Director === "Christopher Nolan")
     .map(obj => Number(obj.imdbRating));
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md
index d0297e13c4d..a2d55337a22 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/functional-programming/use-the-some-method-to-check-that-any-elements-in-an-array-meet-a-criteria.md
@@ -13,7 +13,8 @@ O método `some` funciona verificando se *pelo menos um* dos elementos de um arr
 Por exemplo, o código a seguir verifica se qualquer elemento no array `numbers` é menor que 10:
 
 ```js
-var numbers = [10, 50, 8, 220, 110, 11];
+const numbers = [10, 50, 8, 220, 110, 11];
+
 numbers.some(function(currentValue) {
   return currentValue < 10;
 });
@@ -62,6 +63,7 @@ function checkPositive(arr) {
 
   // Only change code above this line
 }
+
 checkPositive([1, 2, 3, -4, 5]);
 ```
 
@@ -69,9 +71,6 @@ checkPositive([1, 2, 3, -4, 5]);
 
 ```js
 function checkPositive(arr) {
-  // Only change code below this line
   return arr.some(elem => elem > 0);
-  // Only change code above this line
 }
-checkPositive([1, 2, 3, -4, 5]);
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md
index 176f3a943a4..87cec648dfb 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/diff-two-arrays.md
@@ -157,7 +157,7 @@ assert(diffArray([1, 'calf', 3, 'piglet'], [7, 'filly']).length === 6);
 
 ```js
 function diffArray(arr1, arr2) {
-  var newArr = [];
+  const newArr = [];
   return newArr;
 }
 
@@ -168,13 +168,12 @@ diffArray([1, 2, 3, 5], [1, 2, 3, 4, 5]);
 
 ```js
 function diffArray(arr1, arr2) {
-  var newArr = [];
-  var h1 = Object.create(null);
+  const newArr = [];
+  const h1 = Object.create(null);
   arr1.forEach(function(e) {
     h1[e] = e;
   });
-
-  var h2 = Object.create(null);
+  const h2 = Object.create(null);
   arr2.forEach(function(e) {
     h2[e] = e;
   });
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md
index 0440792750e..c2b1339d6d9 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/make-a-person.md
@@ -23,10 +23,19 @@ Execute os testes para ver a saída esperada para cada método. Os métodos que
 
 # --hints--
 
-`Object.keys(bob).length` deve retornar 6.
+Nenhuma propriedade deve ser adicionada. `Object.keys(bob).length` deve sempre retornar 6.
 
 ```js
-assert.deepEqual(Object.keys(bob).length, 6);
+assert.strictEqual(
+  Object.keys((function () {
+    let bob = new Person('Bob Ross');
+    bob.setFirstName('Haskell');
+    bob.setLastName('Curry');
+    bob.setFullName('John Smith');
+    return bob;
+  })()).length,
+  6
+ );
 ```
 
 `bob instanceof Pessoa` deve retornar `true`.
@@ -139,7 +148,7 @@ if(bob){
 ## --seed-contents--
 
 ```js
-var Person = function(firstAndLast) {
+const Person = function(firstAndLast) {
   // Only change code below this line
   // Complete the method below and implement the others similarly
   this.getFullName = function() {
@@ -148,16 +157,16 @@ var Person = function(firstAndLast) {
   return firstAndLast;
 };
 
-var bob = new Person('Bob Ross');
+const bob = new Person('Bob Ross');
 bob.getFullName();
 ```
 
 # --solutions--
 
 ```js
-var Person = function(firstAndLast) {
+const Person = function(firstAndLast) {
 
-  var firstName, lastName;
+  let firstName, lastName;
 
   function updateName(str) {
     firstName = str.split(" ")[0];
@@ -192,6 +201,6 @@ var Person = function(firstAndLast) {
   };
 };
 
-var bob = new Person('Bob Ross');
+const bob = new Person('Bob Ross');
 bob.getFullName();
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md
index 5d7e4344456..ffbbd4805e1 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md
@@ -51,8 +51,8 @@ assert.deepEqual(
 
 ```js
 function orbitalPeriod(arr) {
-  var GM = 398600.4418;
-  var earthRadius = 6367.4447;
+  const GM = 398600.4418;
+  const earthRadius = 6367.4447;
   return arr;
 }
 
@@ -63,9 +63,9 @@ orbitalPeriod([{name : "sputnik", avgAlt : 35873.5553}]);
 
 ```js
 function orbitalPeriod(arr) {
-  var GM = 398600.4418;
-  var earthRadius = 6367.4447;
-  var TAU = 2 * Math.PI;
+  const GM = 398600.4418;
+  const earthRadius = 6367.4447;
+  const TAU = 2 * Math.PI;
   return arr.map(function(obj) {
     return {
       name: obj.name,
@@ -73,6 +73,4 @@ function orbitalPeriod(arr) {
     };
   });
 }
-
-orbitalPeriod([{name : "sputkin", avgAlt : 35873.5553}]);
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md
index 4991be87825..46a74b25846 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple.md
@@ -61,7 +61,6 @@ function smallestCommons(arr) {
   return arr;
 }
 
-
 smallestCommons([1,5]);
 ```
 
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md
index afdff0e631d..4191a511219 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/wherefore-art-thou.md
@@ -103,7 +103,7 @@ assert.deepEqual(
 
 ```js
 function whatIsInAName(collection, source) {
-  var arr = [];
+  const arr = [];
   // Only change code below this line
 
 
@@ -118,8 +118,8 @@ whatIsInAName([{ first: "Romeo", last: "Montague" }, { first: "Mercutio", last:
 
 ```js
 function whatIsInAName(collection, source) {
-  var arr = [];
-  var keys = Object.keys(source);
+  const arr = [];
+  const keys = Object.keys(source);
   collection.forEach(function(e) {
     if(keys.every(function(key) {return e[key] === source[key];})) {
       arr.push(e);
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md
index a5aa3e63ce6..a5795068b34 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher.md
@@ -51,7 +51,6 @@ assert(
 
 ```js
 function rot13(str) {
-
   return str;
 }
 
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md
index 283ed15f2bb..4ddb07a5187 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register.md
@@ -186,7 +186,7 @@ assert.deepEqual(
 
 ```js
 function checkCashRegister(price, cash, cid) {
-  var change;
+  let change;
   return change;
 }
 
@@ -196,54 +196,57 @@ checkCashRegister(19.5, 20, [["PENNY", 1.01], ["NICKEL", 2.05], ["DIME", 3.1], [
 # --solutions--
 
 ```js
-var denom = [
-    { name: 'ONE HUNDRED', val: 100},
-    { name: 'TWENTY', val: 20},
-    { name: 'TEN', val: 10},
-    { name: 'FIVE', val: 5},
-    { name: 'ONE', val: 1},
-    { name: 'QUARTER', val: 0.25},
-    { name: 'DIME', val: 0.1},
-    { name: 'NICKEL', val: 0.05},
-    { name: 'PENNY', val: 0.01}
+const denom = [
+  { name: "ONE HUNDRED", val: 100 },
+  { name: "TWENTY", val: 20 },
+  { name: "TEN", val: 10 },
+  { name: "FIVE", val: 5 },
+  { name: "ONE", val: 1 },
+  { name: "QUARTER", val: 0.25 },
+  { name: "DIME", val: 0.1 },
+  { name: "NICKEL", val: 0.05 },
+  { name: "PENNY", val: 0.01 },
 ];
 
 function checkCashRegister(price, cash, cid) {
- var output = {status: null, change: []};
- var change = cash - price;
- var register = cid.reduce(function(acc, curr) {
- acc.total += curr[1];
- acc[curr[0]] = curr[1];
- return acc;
- }, {total: 0});
- if(register.total === change) {
- output.status = 'CLOSED';
- output.change = cid;
- return output;
- }
- if(register.total < change) {
- output.status = 'INSUFFICIENT_FUNDS';
- return output;
- }
- var change_arr = denom.reduce(function(acc, curr) {
- var value = 0;
- while(register[curr.name] > 0 && change >= curr.val) {
- change -= curr.val;
- register[curr.name] -= curr.val;
- value += curr.val;
- change = Math.round(change * 100) / 100;
- }
- if(value > 0) {
- acc.push([ curr.name, value ]);
- }
- return acc;
- }, []);
- if(change_arr.length < 1 || change > 0) {
- output.status = 'INSUFFICIENT_FUNDS';
- return output;
- }
- output.status = 'OPEN';
- output.change = change_arr;
- return output;
+  const output = { status: null, change: [] };
+  let change = cash - price;
+  const register = cid.reduce(
+    function (acc, curr) {
+      acc.total += curr[1];
+      acc[curr[0]] = curr[1];
+      return acc;
+    },
+    { total: 0 }
+  );
+  if (register.total === change) {
+    output.status = "CLOSED";
+    output.change = cid;
+    return output;
+  }
+  if (register.total < change) {
+    output.status = "INSUFFICIENT_FUNDS";
+    return output;
+  }
+  const change_arr = denom.reduce(function (acc, curr) {
+    let value = 0;
+    while (register[curr.name] > 0 && change >= curr.val) {
+      change -= curr.val;
+      register[curr.name] -= curr.val;
+      value += curr.val;
+      change = Math.round(change * 100) / 100;
+    }
+    if (value > 0) {
+      acc.push([curr.name, value]);
+    }
+    return acc;
+  }, []);
+  if (change_arr.length < 1 || change > 0) {
+    output.status = "INSUFFICIENT_FUNDS";
+    return output;
+  }
+  output.status = "OPEN";
+  output.change = change_arr;
+  return output;
 }
 ```
diff --git a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md
index ed254b9ac9e..2582b57d2f1 100644
--- a/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md
+++ b/curriculum/challenges/portuguese/02-javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/palindrome-checker.md
@@ -107,8 +107,6 @@ function palindrome(str) {
   return true;
 }
 
-
-
 palindrome("eye");
 ```
 
diff --git a/curriculum/challenges/portuguese/03-front-end-development-libraries/front-end-development-libraries-projects/build-a-markdown-previewer.md b/curriculum/challenges/portuguese/03-front-end-development-libraries/front-end-development-libraries-projects/build-a-markdown-previewer.md
index 11b9de70eba..73c349f7098 100644
--- a/curriculum/challenges/portuguese/03-front-end-development-libraries/front-end-development-libraries-projects/build-a-markdown-previewer.md
+++ b/curriculum/challenges/portuguese/03-front-end-development-libraries/front-end-development-libraries-projects/build-a-markdown-previewer.md
@@ -22,7 +22,7 @@ Você pode usar qualquer mistura de HTML, JavaScript, CSS, Bootstrap, SASS, Reac
 
 **Especificação de usuário nº 4:** quando insiro marcação do GitHub no elemento `#editor`, o texto é renderizado como HTML no elemento `#preview` enquanto eu escrevo (DICA: você não precisa analisar a marcação você mesmo - você pode importar a biblioteca Marked para isso: <https://cdnjs.com/libraries/marked>).
 
-**Especificação de usuário nº 5:** quando meu pré-visualizador de marcação carregar pela primeira vez, o texto padrão no campo `#editor` deve conter uma marcação válida que represente pelo menos um de cada um dos elementos a seguir: um header (tamanho H1), um subheader (tamanho H2), um link, um código em linha, um código de bloco, uma lista de item, um blockquote, uma imagem e um texto em negrito.
+**Especificação de usuário nº 5:** quando meu pré-visualizador de marcação carregar pela primeira vez, o texto padrão no campo `#editor` deve conter uma marcação válida que represente pelo menos um de cada um dos elementos a seguir: um elemento (tamanho H1), um subelemento de título (tamanho H2), um link, um código em linha, um código de bloco, uma lista de item, um blockquote, uma imagem e um texto em negrito.
 
 **Especificação de usuário nº 6:** quando meu pré-visualizador de marcação carregar pela primeira vez, a marcação padrão no campo `#editor` deve ser renderizada como HTML no elemento `#preview`.
 
diff --git a/curriculum/challenges/portuguese/03-front-end-development-libraries/react/access-props-using-this.props.md b/curriculum/challenges/portuguese/03-front-end-development-libraries/react/access-props-using-this.props.md
index 49d8f701795..ab80387e9b1 100644
--- a/curriculum/challenges/portuguese/03-front-end-development-libraries/react/access-props-using-this.props.md
+++ b/curriculum/challenges/portuguese/03-front-end-development-libraries/react/access-props-using-this.props.md
@@ -14,67 +14,54 @@ Sempre que você se refere a um componente de classe dentro dele mesmo, você us
 
 # --instructions--
 
-Renderize uma instância do componente `ReturnTempPassword` no componente parente `ResetPassword`. Aqui, dê a `ReturnTempPassword` à prop `tempPassword` e atribua a ela o valor de uma string que tenha pelo menos 8 caracteres. Dentro do filho, `ReturnTempPassword`, acesse a prop `tempPassword` dentro das tags `strong` para certificar-se que o usuário veja a senha temporária.
+Renderize uma instância do componente `Welcome` no componente parente `App`. Aqui, dê a `Welcome` uma "prop" `name` e atribua a ela um valor de uma string. Dentro do elemento filho, `Welcome`, acesse a propriedade `name` dentro das tags `strong`.
 
 # --hints--
 
-O componente `ResetPassword` deve retornar um único elemento `div`.
+O componente `App` deve retornar um único elemento `div`.
 
 ```js
 assert(
   (function () {
-    const mockedComponent = Enzyme.mount(React.createElement(ResetPassword));
+    const mockedComponent = Enzyme.mount(React.createElement(App));
     return mockedComponent.children().type() === 'div';
   })()
 );
 ```
 
-O quarto filho de `ResetPassword` deve ser o componente `ReturnTempPassword`.
+O elemento filho de `App` deve ser o componente `Welcome`.
 
 ```js
 assert(
   (function () {
-    const mockedComponent = Enzyme.mount(React.createElement(ResetPassword));
+    const mockedComponent = Enzyme.mount(React.createElement(App));
     return (
-      mockedComponent.children().childAt(3).name() === 'ReturnTempPassword'
+      mockedComponent.children().childAt(0).name() === 'Welcome'
     );
   })()
 );
 ```
 
-O componente `ReturnTempPassword` deve ter uma prop chamada `tempPassword`.
+O componente `Welcome` deve ter uma prop chamada `name`.
 
 ```js
 assert(
   (function () {
-    const mockedComponent = Enzyme.mount(React.createElement(ResetPassword));
-    return mockedComponent.find('ReturnTempPassword').props().tempPassword;
+    const mockedComponent = Enzyme.mount(React.createElement(App));
+    return mockedComponent.find('Welcome').props().name;
   })()
 );
 ```
 
-A prop `tempPassword` de `ReturnTempPassword` deve ser igual uma string de pelo menos 8 caracteres.
+O componente `Welcome` deve exibir a string que você passou como a prop `name` dentro das tags `strong`.
 
 ```js
 assert(
   (function () {
-    const mockedComponent = Enzyme.mount(React.createElement(ResetPassword));
-    const temp = mockedComponent.find('ReturnTempPassword').props()
-      .tempPassword;
-    return typeof temp === 'string' && temp.length >= 8;
-  })()
-);
-```
-
-O componente `ReturnTempPassword` deve exibir a senha que você criou como a prop `tempPassword` dentro das tags `strong`.
-
-```js
-assert(
-  (function () {
-    const mockedComponent = Enzyme.mount(React.createElement(ResetPassword));
+    const mockedComponent = Enzyme.mount(React.createElement(App));
     return (
       mockedComponent.find('strong').text() ===
-      mockedComponent.find('ReturnTempPassword').props().tempPassword
+      mockedComponent.find('Welcome').props().name
     );
   })()
 );
@@ -85,13 +72,13 @@ assert(
 ## --after-user-code--
 
 ```jsx
-ReactDOM.render(<ResetPassword />, document.getElementById('root'))
+ReactDOM.render(<App />, document.getElementById('root'))
 ```
 
 ## --seed-contents--
 
 ```jsx
-class ReturnTempPassword extends React.Component {
+class App extends React.Component {
   constructor(props) {
     super(props);
 
@@ -100,14 +87,14 @@ class ReturnTempPassword extends React.Component {
     return (
         <div>
             { /* Change code below this line */ }
-            <p>Your temporary password is: <strong></strong></p>
+            <Welcome />
             { /* Change code above this line */ }
         </div>
     );
   }
 };
 
-class ResetPassword extends React.Component {
+class Welcome extends React.Component {
   constructor(props) {
     super(props);
 
@@ -115,11 +102,8 @@ class ResetPassword extends React.Component {
   render() {
     return (
         <div>
-          <h2>Reset Password</h2>
-          <h3>We've generated a new temporary password for you.</h3>
-          <h3>Please reset this password from your account settings ASAP.</h3>
           { /* Change code below this line */ }
-
+          <p>Hello, <strong></strong>!</p>
           { /* Change code above this line */ }
         </div>
     );
@@ -130,7 +114,7 @@ class ResetPassword extends React.Component {
 # --solutions--
 
 ```jsx
-class ReturnTempPassword extends React.Component {
+class Welcome extends React.Component {
   constructor(props) {
     super(props);
 
@@ -138,28 +122,27 @@ class ReturnTempPassword extends React.Component {
   render() {
     return (
         <div>
-            <p>Your temporary password is: <strong>{this.props.tempPassword}</strong></p>
-        </div>
-    );
-  }
-};
-
-class ResetPassword extends React.Component {
-  constructor(props) {
-    super(props);
-
-  }
-  render() {
-    return (
-        <div>
-          <h2>Reset Password</h2>
-          <h3>We've generated a new temporary password for you.</h3>
-          <h3>Please reset this password from your account settings ASAP.</h3>
           { /* Change code below this line */ }
-          <ReturnTempPassword tempPassword="serrPbqrPnzc" />
+          <p>Hello, <strong>{this.props.name}</strong>!</p>
           { /* Change code above this line */ }
         </div>
     );
   }
 };
+
+class App extends React.Component {
+  constructor(props) {
+    super(props);
+
+  }
+  render() {
+    return (
+        <div>
+            { /* Change code below this line */ }
+            <Welcome name="Quincy"/>
+            { /* Change code above this line */ }
+        </div>
+    );
+  }
+};
 ```
diff --git a/curriculum/challenges/portuguese/03-front-end-development-libraries/react/compose-react-components.md b/curriculum/challenges/portuguese/03-front-end-development-libraries/react/compose-react-components.md
index bd8348bd7e0..0ec0809f81c 100644
--- a/curriculum/challenges/portuguese/03-front-end-development-libraries/react/compose-react-components.md
+++ b/curriculum/challenges/portuguese/03-front-end-development-libraries/react/compose-react-components.md
@@ -14,7 +14,7 @@ Enquanto os desafios continuam a usar composições mais complexas com component
 
 No editor de código, o componente `TypesOfFood` já está renderizando um componente chamado `Vegetables`. Além disso, há o componente `Fruits` do último desafio.
 
-Aninhe dois componentes dentro de `Fruits` — primeiro `NonCitrus`, e depois `Citrus`. Ambos os componentes são fornecidos nos bastidores. Em seguida, aninhe o componente de classe `Fruits` dentro do componente `TypesOfFood`, abaixo do cabeçalho `h1` e acima de `Vegetables`. O resultado deve ser uma série de componentes aninhados, que usa dois tipos de componentes diferentes.
+Aninhe dois componentes dentro de `Fruits` — primeiro `NonCitrus`, e depois `Citrus`. Ambos os componentes são fornecidos nos bastidores. Em seguida, aninhe o componente de classe `Fruits` dentro do componente `TypesOfFood`, abaixo do elemento de título `h1` e acima de `Vegetables`. O resultado deve ser uma série de componentes aninhados, que usa dois tipos de componentes diferentes.
 
 # --hints--
 
diff --git a/curriculum/challenges/portuguese/03-front-end-development-libraries/react/create-a-controlled-form.md b/curriculum/challenges/portuguese/03-front-end-development-libraries/react/create-a-controlled-form.md
index 1ee0593fbd0..25f93e75cf6 100644
--- a/curriculum/challenges/portuguese/03-front-end-development-libraries/react/create-a-controlled-form.md
+++ b/curriculum/challenges/portuguese/03-front-end-development-libraries/react/create-a-controlled-form.md
@@ -109,7 +109,7 @@ assert(
 );
 ```
 
-O título `h1` deve renderizar o valor do campo `submit` do estado do componente.
+O elemento de título `h1` deve renderizar o valor do campo `submit` do estado do componente.
 
 ```js
 (() => {
diff --git a/curriculum/challenges/portuguese/03-front-end-development-libraries/react/create-a-react-component.md b/curriculum/challenges/portuguese/03-front-end-development-libraries/react/create-a-react-component.md
index a123ce7cc76..b06f7b3308b 100644
--- a/curriculum/challenges/portuguese/03-front-end-development-libraries/react/create-a-react-component.md
+++ b/curriculum/challenges/portuguese/03-front-end-development-libraries/react/create-a-react-component.md
@@ -38,7 +38,7 @@ O componente React deve retornar um elemento `div`.
 assert(Enzyme.shallow(React.createElement(MyComponent)).type() === 'div');
 ```
 
-A `div` retornada deve renderizar um título `h1` dentro dele.
+A `div` retornada deve renderizar um elemento de título `h1` dentro dele.
 
 ```js
 assert(
@@ -48,7 +48,7 @@ assert(
 );
 ```
 
-O título `h1` deve conter a string `Hello React!`.
+O elemento de título `h1` deve conter a string `Hello React!`.
 
 ```js
 assert(
diff --git a/curriculum/challenges/portuguese/03-front-end-development-libraries/react/render-state-in-the-user-interface-another-way.md b/curriculum/challenges/portuguese/03-front-end-development-libraries/react/render-state-in-the-user-interface-another-way.md
index b711aee1c53..4a96203184c 100644
--- a/curriculum/challenges/portuguese/03-front-end-development-libraries/react/render-state-in-the-user-interface-another-way.md
+++ b/curriculum/challenges/portuguese/03-front-end-development-libraries/react/render-state-in-the-user-interface-another-way.md
@@ -27,7 +27,7 @@ assert(
 );
 ```
 
-`MyComponent` deve renderizar um título `h1` que está dentro de um único `div`.
+`MyComponent` deve renderizar um elemento de título `h1` que está dentro de um único `div`.
 
 ```js
 assert(
@@ -44,7 +44,7 @@ A tag `h1` renderizada deve ter uma referência a `{name}`.
   assert(/<h1>\n*\s*\{\s*name\s*\}\s*\n*<\/h1>/.test(getUserInput('index')));
 ```
 
-O título `h1` renderizado deve conter apenas texto renderizado do estado do componente.
+O elemento de título `h1` renderizado deve conter apenas texto renderizado do estado do componente.
 
 ```js
 async () => {
diff --git a/curriculum/challenges/portuguese/03-front-end-development-libraries/react/render-state-in-the-user-interface.md b/curriculum/challenges/portuguese/03-front-end-development-libraries/react/render-state-in-the-user-interface.md
index 56604246e17..6b8c7aae112 100644
--- a/curriculum/challenges/portuguese/03-front-end-development-libraries/react/render-state-in-the-user-interface.md
+++ b/curriculum/challenges/portuguese/03-front-end-development-libraries/react/render-state-in-the-user-interface.md
@@ -33,7 +33,7 @@ assert(
 );
 ```
 
-`MyComponent` deve renderizar um título `h1` que está dentro de um único `div`.
+`MyComponent` deve renderizar um elemento de título `h1` que está dentro de um único `div`.
 
 ```js
 assert(
@@ -43,7 +43,7 @@ assert(
 );
 ```
 
-O título `h1` renderizado deve conter apenas texto renderizado do estado do componente.
+O elemento de título `h1` renderizado deve conter apenas texto renderizado do estado do componente.
 
 ```js
 async () => {
diff --git a/curriculum/challenges/portuguese/03-front-end-development-libraries/react/set-state-with-this.setstate.md b/curriculum/challenges/portuguese/03-front-end-development-libraries/react/set-state-with-this.setstate.md
index a3e26d5e0af..95d02d99e7c 100644
--- a/curriculum/challenges/portuguese/03-front-end-development-libraries/react/set-state-with-this.setstate.md
+++ b/curriculum/challenges/portuguese/03-front-end-development-libraries/react/set-state-with-this.setstate.md
@@ -35,13 +35,13 @@ assert(
 );
 ```
 
-`MyComponent` deve retornar um título `h1`.
+`MyComponent` deve retornar um elemento de título `h1`.
 
 ```js
 assert(Enzyme.mount(React.createElement(MyComponent)).find('h1').length === 1);
 ```
 
-O título `h1` renderizado deve conter apenas texto renderizado do estado do componente.
+O elemento de título `h1` renderizado deve conter apenas texto renderizado do estado do componente.
 
 ```js
 async () => {
diff --git a/curriculum/challenges/portuguese/05-back-end-development-and-apis/basic-node-and-express/use-the-.env-file.md b/curriculum/challenges/portuguese/05-back-end-development-and-apis/basic-node-and-express/use-the-.env-file.md
index 29531b1d6de..ccb30068d68 100644
--- a/curriculum/challenges/portuguese/05-back-end-development-and-apis/basic-node-and-express/use-the-.env-file.md
+++ b/curriculum/challenges/portuguese/05-back-end-development-and-apis/basic-node-and-express/use-the-.env-file.md
@@ -22,6 +22,8 @@ Em seguida, no manipulador de rota `/json` do GET que você criou no último des
 
 **Observação:** se você estiver usando o Replit, você não poderá criar um arquivo `.env`. Em vez disso, use a aba embutida <dfn>SECRETS</dfn> para adicionar a variável.
 
+Se você estiver trabalhando localmente, precisará do pacote `dotenv`. Ele carrega as variáveis de ambiente do seu arquivo `.env` em `process.env`. Instale-o com `npm install dotenv`. Em seguida, na parte superior do seu arquivo `myApp.js`, importe e carregue as variáveis com `require('dotenv').config()`.
+
 # --hints--
 
 A resposta do endpoint `/json` deve ser alterada de acordo com a variável de ambiente `MESSAGE_STYLE`
diff --git a/curriculum/challenges/portuguese/10-coding-interview-prep/data-structures/delete-a-leaf-node-in-a-binary-search-tree.md b/curriculum/challenges/portuguese/10-coding-interview-prep/data-structures/delete-a-leaf-node-in-a-binary-search-tree.md
index 65a3cb21ff3..a6c71d5b4a3 100644
--- a/curriculum/challenges/portuguese/10-coding-interview-prep/data-structures/delete-a-leaf-node-in-a-binary-search-tree.md
+++ b/curriculum/challenges/portuguese/10-coding-interview-prep/data-structures/delete-a-leaf-node-in-a-binary-search-tree.md
@@ -46,6 +46,25 @@ assert(
 );
 ```
 
+Tentar remover um elemento de uma árvore vazia deve retornar `null`.
+
+```js
+assert(
+  (function () {
+    var test = false;
+    if (typeof BinarySearchTree !== 'undefined') {
+      test = new BinarySearchTree();
+    } else {
+      return false;
+    }
+    if (typeof test.remove !== 'function') {
+      return false;
+    }
+    return test.remove(100) == null;
+  })()
+);
+```
+
 Tentar remover um elemento que não existe deve retornar `null`.
 
 ```js
@@ -60,6 +79,8 @@ assert(
     if (typeof test.remove !== 'function') {
       return false;
     }
+    test.add(15);
+    test.add(30);
     return test.remove(100) == null;
   })()
 );
diff --git a/curriculum/challenges/portuguese/10-coding-interview-prep/project-euler/problem-14-longest-collatz-sequence.md b/curriculum/challenges/portuguese/10-coding-interview-prep/project-euler/problem-14-longest-collatz-sequence.md
index 42c05557681..ecc0ec53486 100644
--- a/curriculum/challenges/portuguese/10-coding-interview-prep/project-euler/problem-14-longest-collatz-sequence.md
+++ b/curriculum/challenges/portuguese/10-coding-interview-prep/project-euler/problem-14-longest-collatz-sequence.md
@@ -22,7 +22,7 @@ Podemos ver que essa sequência (começando em 13 e terminando em 1) contém 10
 
 Qual número inicial, sob o `limit` (limite) definido, produz a sequência mais longa?
 
-**Observação:** uma vez iniciada, os termos na sequência podem passar de um milhão.
+**Observação:** uma vez iniciada, os termos na sequência podem passar acima do `limit`.
 
 # --hints--