89 lines
2.3 KiB
Markdown
89 lines
2.3 KiB
Markdown
---
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id: 56bbb991ad1ed5201cd392cc
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challengeType: 1
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videoUrl: 'https://scrimba.com/c/cRbVZAB'
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forumTopicId: 18236
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localeTitle: 使用 pop() 操作数组
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---
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## Description
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<section id='description'>
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改变数组中数据的另一种方法是用<code>.pop()</code>函数。
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<code>.pop()</code>函数用来“抛出”一个数组末尾的值。我们可以把这个“抛出”的值赋给一个变量存储起来。换句话说就是<code>.pop()</code>函数移除数组末尾的元素并返回这个元素。
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数组中任何类型的元素（数值，字符串，甚至是数组）可以被“抛出来” 。
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```js
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var threeArr = [1, 4, 6];
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var oneDown = threeArr.pop();
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console.log(oneDown); // Returns 6
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console.log(threeArr); // Returns [1, 4]
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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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使用<code>.pop()</code>函数移除<code>myArray</code>中的最后一个元素，并且把“抛出”的值赋给<code>removedFromMyArray</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: <code>myArray</code>应该只包含<code>[["John", 23]]</code>。
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testString: assert((function(d){if(d[0][0] == 'John' && d[0][1] === 23 && d[1] == undefined){return true;}else{return false;}})(myArray));
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- text: 对<code>myArray</code>使用<code>pop()</code>函数。
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testString: assert(/removedFromMyArray\s*=\s*myArray\s*.\s*pop\s*(\s*)/.test(code));
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- text: <code>removedFromMyArray</code>应该只包含<code>["cat", 2]</code>。
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testString: assert((function(d){if(d[0] == 'cat' && d[1] === 2 && d[2] == undefined){return true;}else{return false;}})(removedFromMyArray));
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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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// Example
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var ourArray = [1,2,3];
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var removedFromOurArray = ourArray.pop();
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// removedFromOurArray now equals 3, and ourArray now equals [1,2]
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// Setup
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var myArray = [["John", 23], ["cat", 2]];
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// Only change code below this line.
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var removedFromMyArray;
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```
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</div>
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### After Test
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<div id='js-teardown'>
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```js
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(function(y, z){return 'myArray = ' + JSON.stringify(y) + ' & removedFromMyArray = ' + JSON.stringify(z);})(myArray, removedFromMyArray);
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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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var myArray = [["John", 23], ["cat", 2]];
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var removedFromMyArray = myArray.pop();
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```
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</section>
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