diff --git a/curriculum/challenges/english/01-responsive-web-design/responsive-web-design-projects/build-a-personal-portfolio-webpage.md b/curriculum/challenges/english/01-responsive-web-design/responsive-web-design-projects/build-a-personal-portfolio-webpage.md
index cc2c07f279f..afe98f114e4 100644
--- a/curriculum/challenges/english/01-responsive-web-design/responsive-web-design-projects/build-a-personal-portfolio-webpage.md
+++ b/curriculum/challenges/english/01-responsive-web-design/responsive-web-design-projects/build-a-personal-portfolio-webpage.md
@@ -91,7 +91,7 @@ Your `#navbar` element should contain at least one `a` element whose `href` attr
 
 ```js
 const links = [...document.querySelectorAll('#navbar a')].filter(
-  (nav) => (nav?.getAttribute('href') || '').substr(0, 1) === '#'
+  (nav) => (nav?.getAttribute('href') || '').substring(0, 1) === '#'
 );
 
 assert.isAbove(
diff --git a/curriculum/challenges/english/05-back-end-development-and-apis/back-end-development-and-apis-projects/exercise-tracker.md b/curriculum/challenges/english/05-back-end-development-and-apis/back-end-development-and-apis-projects/exercise-tracker.md
index c95a17cfc98..2a783db5833 100644
--- a/curriculum/challenges/english/05-back-end-development-and-apis/back-end-development-and-apis-projects/exercise-tracker.md
+++ b/curriculum/challenges/english/05-back-end-development-and-apis/back-end-development-and-apis-projects/exercise-tracker.md
@@ -79,7 +79,7 @@ async (getUserInput) => {
   const res = await fetch(url + '/api/users', {
     method: 'POST',
     headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
-    body: `username=fcc_test_${Date.now()}`.substr(0, 29)
+    body: `username=fcc_test_${Date.now()}`.substring(0, 29)
   });
   assert.isTrue(res.ok);
   if(!res.ok) {
@@ -96,7 +96,7 @@ async (getUserInput) => {
   const res = await fetch(url + '/api/users', {
     method: 'POST',
     headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
-    body: `username=fcc_test_${Date.now()}`.substr(0, 29)
+    body: `username=fcc_test_${Date.now()}`.substring(0, 29)
   });
   if (res.ok) {
     const { _id, username } = await res.json();
@@ -164,7 +164,7 @@ async (getUserInput) => {
   const res = await fetch(url + '/api/users', {
     method: 'POST',
     headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
-    body: `username=fcc_test_${Date.now()}`.substr(0, 29)
+    body: `username=fcc_test_${Date.now()}`.substingr(0, 29)
   });
   if (res.ok) {
     const { _id, username } = await res.json();
@@ -198,7 +198,7 @@ async (getUserInput) => {
   const res = await fetch(url + '/api/users', {
     method: 'POST',
     headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
-    body: `username=fcc_test_${Date.now()}`.substr(0, 29)
+    body: `username=fcc_test_${Date.now()}`.substring(0, 29)
   });
   if (res.ok) {
     const { _id, username } = await res.json();
@@ -237,7 +237,7 @@ async (getUserInput) => {
   const res = await fetch(url + '/api/users', {
     method: 'POST',
     headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
-    body: `username=fcc_test_${Date.now()}`.substr(0, 29)
+    body: `username=fcc_test_${Date.now()}`.substring(0, 29)
   });
   if (res.ok) {
     const { _id, username } = await res.json();
@@ -276,7 +276,7 @@ async (getUserInput) => {
   const res = await fetch(url + '/api/users', {
     method: 'POST',
     headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
-    body: `username=fcc_test_${Date.now()}`.substr(0, 29)
+    body: `username=fcc_test_${Date.now()}`.substring(0, 29)
   });
   if (res.ok) {
     const { _id, username } = await res.json();
@@ -319,7 +319,7 @@ async(getUserInput) => {
     headers: {
       'Content-Type': 'application/x-www-form-urlencoded'
     },
-    body: `username=fcc_test_${Date.now()}`.substr(0, 29)
+    body: `username=fcc_test_${Date.now()}`.substring(0, 29)
   })
   if(res.ok){
     const {_id, username} = await res.json();
@@ -363,7 +363,7 @@ async(getUserInput) => {
     headers: {
       'Content-Type': 'application/x-www-form-urlencoded'
     },
-    body: `username=fcc_test_${Date.now()}`.substr(0, 29)
+    body: `username=fcc_test_${Date.now()}`.substring(0, 29)
   });
   if(res.ok) {
     const {_id, username} = await res.json();
@@ -410,7 +410,7 @@ async(getUserInput) => {
     headers: {
       'Content-Type': 'application/x-www-form-urlencoded',
     },
-    body: `username=fcc_test_${Date.now()}`.substr(0,29)
+    body: `username=fcc_test_${Date.now()}`.substring(0,29)
   });
   if(res.ok) {
     const {_id, username} = await res.json();
@@ -457,7 +457,7 @@ async(getUserInput) => {
     headers: {
       'Content-Type': 'application/x-www-form-urlencoded',
     },
-    body: `username=fcc_test_${Date.now()}`.substr(0,29)
+    body: `username=fcc_test_${Date.now()}`.substring(0,29)
   });
   if(res.ok) {
     const {_id, username} = await res.json();
@@ -504,7 +504,7 @@ async(getUserInput) => {
     headers: {
       'Content-Type': 'application/x-www-form-urlencoded',
     },
-    body: `username=fcc_test_${Date.now()}`.substr(0,29)
+    body: `username=fcc_test_${Date.now()}`.substring(0,29)
   });
   if(res.ok) {
     const {_id, username} = await res.json();
@@ -549,7 +549,7 @@ async (getUserInput) => {
   const res = await fetch(url + '/api/users', {
     method: 'POST',
     headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
-    body: `username=fcc_test_${Date.now()}`.substr(0, 29)
+    body: `username=fcc_test_${Date.now()}`.substring(0, 29)
   });
   if (res.ok) {
     const { _id, username } = await res.json();
diff --git a/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-13-large-sum.md b/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-13-large-sum.md
index badc6ffd8b4..7e4db74fcb7 100644
--- a/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-13-large-sum.md
+++ b/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-13-large-sum.md
@@ -278,7 +278,7 @@ function largeSum(arr) {
 
   sum = sum.toString(10);
 
-  sum = sum.substr(0, 1) + sum.substr(2);
+  sum = sum.substring(0, 1) + sum.substring(2);
 
   let firstTen = sum.slice(0, 10);
   return parseInt(firstTen, 10);
diff --git a/curriculum/challenges/english/10-coding-interview-prep/rosetta-code/iban.md b/curriculum/challenges/english/10-coding-interview-prep/rosetta-code/iban.md
index 151b979a3f7..dde7926e041 100644
--- a/curriculum/challenges/english/10-coding-interview-prep/rosetta-code/iban.md
+++ b/curriculum/challenges/english/10-coding-interview-prep/rosetta-code/iban.md
@@ -95,10 +95,10 @@ function isValid(iban) {
     iban = __helpers.removeWhiteSpace(iban)
     if (!iban.match(/^[\dA-Z]+$/)) return false
     var len = iban.length
-    if (len != ibanLen[iban.substr(0,2)]) return false
-    iban = iban.substr(4) + iban.substr(0,4)
+    if (len != ibanLen[iban.substring(0,2)]) return false
+    iban = iban.substring(4) + iban.substring(0,4)
     for (var s='', i=0; i<len; i+=1) s+=parseInt(iban.charAt(i),36)
-    for (var m=s.substr(0,15)%97, s=s.substr(15); s; s=s.substr(13)) m=(m+s.substr(0,13))%97
+    for (var m=s.substring(0,15)%97, s=s.substring(15); s; s=s.substring(13)) m=(m+s.substring(0,13))%97
     return m == 1
 }
 ```
diff --git a/curriculum/challenges/english/10-coding-interview-prep/rosetta-code/longest-common-subsequence.md b/curriculum/challenges/english/10-coding-interview-prep/rosetta-code/longest-common-subsequence.md
index e72d2a114b0..7b8dd9dbfc5 100644
--- a/curriculum/challenges/english/10-coding-interview-prep/rosetta-code/longest-common-subsequence.md
+++ b/curriculum/challenges/english/10-coding-interview-prep/rosetta-code/longest-common-subsequence.md
@@ -84,8 +84,8 @@ function lcs(a, b) {
 
 ```js
 function lcs(a, b) {
-  var aSub = a.substr(0, a.length - 1);
-  var bSub = b.substr(0, b.length - 1);
+  var aSub = a.substring(0, a.length - 1);
+  var bSub = b.substring(0, b.length - 1);
 
   if (a.length === 0 || b.length === 0) {
     return '';
diff --git a/curriculum/challenges/english/14-responsive-web-design-22/build-a-personal-portfolio-webpage-project/build-a-personal-portfolio-webpage.md b/curriculum/challenges/english/14-responsive-web-design-22/build-a-personal-portfolio-webpage-project/build-a-personal-portfolio-webpage.md
index cc2c07f279f..afe98f114e4 100644
--- a/curriculum/challenges/english/14-responsive-web-design-22/build-a-personal-portfolio-webpage-project/build-a-personal-portfolio-webpage.md
+++ b/curriculum/challenges/english/14-responsive-web-design-22/build-a-personal-portfolio-webpage-project/build-a-personal-portfolio-webpage.md
@@ -91,7 +91,7 @@ Your `#navbar` element should contain at least one `a` element whose `href` attr
 
 ```js
 const links = [...document.querySelectorAll('#navbar a')].filter(
-  (nav) => (nav?.getAttribute('href') || '').substr(0, 1) === '#'
+  (nav) => (nav?.getAttribute('href') || '').substring(0, 1) === '#'
 );
 
 assert.isAbove(