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f1c9b08cf3
This includes certificates (where it does nothing), but does not include any translations.
77 lines
1.9 KiB
Markdown
77 lines
1.9 KiB
Markdown
---
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id: 587d7b89367417b2b2512b4b
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title: Use Destructuring Assignment to Assign Variables from Arrays
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challengeType: 1
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isHidden: false
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forumTopicId: 301213
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---
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## Description
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<section id='description'>
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ES6 makes destructuring arrays as easy as destructuring objects.
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One key difference between the spread operator and array destructuring is that the spread operator unpacks all contents of an array into a comma-separated list. Consequently, you cannot pick or choose which elements you want to assign to variables.
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Destructuring an array lets us do exactly that:
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```js
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const [a, b] = [1, 2, 3, 4, 5, 6];
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console.log(a, b); // 1, 2
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```
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The variable <code>a</code> is assigned the first value of the array, and <code>b</code> is assigned the second value of the array.
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We can also access the value at any index in an array with destructuring by using commas to reach the desired index:
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```js
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const [a, b,,, c] = [1, 2, 3, 4, 5, 6];
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console.log(a, b, c); // 1, 2, 5
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```
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</section>
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## Instructions
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<section id='instructions'>
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Use destructuring assignment to swap the values of <code>a</code> and <code>b</code> so that <code>a</code> receives the value stored in <code>b</code>, and <code>b</code> receives the value stored in <code>a</code>.
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: Value of <code>a</code> should be 6, after swapping.
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testString: assert(a === 6);
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- text: Value of <code>b</code> should be 8, after swapping.
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testString: assert(b === 8);
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- text: You should use array destructuring to swap a and b.
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testString: assert(/\[\s*(\w)\s*,\s*(\w)\s*\]\s*=\s*\[\s*\2\s*,\s*\1\s*\]/g.test(code));
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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let a = 8, b = 6;
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// Only change code below this line
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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let a = 8, b = 6;
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[a, b] = [b, a];
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```
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</section>
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