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134 lines
2.9 KiB
Markdown
134 lines
2.9 KiB
Markdown
---
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id: 6437124c4c03dd4c8fb35d56
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title: Step 21
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challengeType: 0
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dashedName: step-21
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---
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# --description--
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Declare an `isEven` function, which takes a `num` parameter and returns `true` if the number is even, and `false` otherwise. Use the modulo operator `%` to determine if a number is even or odd.
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# --hints--
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You should declare an `isEven` variable.
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```js
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assert.match(code, /(?:let|const|var)\s+isEven/);
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```
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You should use `const` to declare your `isEven` variable.
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```js
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assert.match(code, /const\s+isEven/);
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```
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Your `isEven` variable should be a function.
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```js
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assert.isFunction(isEven);
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```
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Your `isEven` function should use arrow syntax.
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```js
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assert.match(code, /const\s+isEven\s*=\s*(\([^)]*\)|[^\s()]+)\s*=>/);
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```
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Your `isEven` function should have a `num` parameter.
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```js
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assert.match(code, /const\s+isEven\s*=\s*(\(\s*num\s*\)|num)\s*=>/);
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```
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Your `isEven` function should use the modulo operator `%`.
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```js
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assert.match(isEven.toString(), /%/);
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```
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Your `isEven` function should return `true` for even numbers.
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```js
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assert.isTrue(isEven(2));
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assert.isTrue(isEven(1000));
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assert.isTrue(isEven(42));
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```
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Your `isEven` function should return `false` for odd numbers.
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```js
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assert.isFalse(isEven(1));
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assert.isFalse(isEven(333));
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assert.isFalse(isEven(777777777));
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```
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# --seed--
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## --seed-contents--
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```html
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<!DOCTYPE html>
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<html lang="en">
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<head>
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<meta charset="utf-8" />
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<meta name="viewport" content="width=device-width, initial-scale=1" />
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<link rel="stylesheet" href="./styles.css" />
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<title>Functional Programming Spreadsheet</title>
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</head>
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<body>
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<div id="container">
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<div></div>
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</div>
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<script src="./script.js"></script>
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</body>
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</html>
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```
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```css
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#container {
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display: grid;
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grid-template-columns: 50px repeat(10, 200px);
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grid-template-rows: repeat(11, 30px);
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}
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.label {
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background-color: lightgray;
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text-align: center;
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vertical-align: middle;
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line-height: 30px;
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}
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```
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```js
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--fcc-editable-region--
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--fcc-editable-region--
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const sum = nums => nums.reduce((acc, el) => acc + el, 0);
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const range = (start, end) => Array(end - start + 1).fill(start).map((element, index) => element + index);
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const charRange = (start, end) => range(start.charCodeAt(0), end.charCodeAt(0)).map(code => String.fromCharCode(code));
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window.onload = () => {
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const container = document.getElementById("container");
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const createLabel = (name) => {
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const label = document.createElement("div");
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label.className = "label";
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label.textContent = name;
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container.appendChild(label);
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}
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const letters = charRange("A", "J");
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letters.forEach(createLabel);
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range(1, 99).forEach(number => {
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createLabel(number);
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letters.forEach(letter => {
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const input = document.createElement("input");
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input.type = "text";
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input.id = letter + number;
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input.ariaLabel = letter + number;
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container.appendChild(input);
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})
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})
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}
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```
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