65 lines
2.4 KiB
Markdown
65 lines
2.4 KiB
Markdown
---
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id: 587d7b89367417b2b2512b49
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title: Use Destructuring Assignment to Assign Variables from Objects
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challengeType: 1
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videoUrl: ''
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localeTitle: 使用解构分配从对象分配变量
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---
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## Description
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<section id="description">我们之前看到扩展运算符如何有效地扩展或解包数组的内容。我们也可以用对象做类似的事情。 <dfn>解构赋值</dfn>是一种特殊的语法，用于将直接从对象获取的值整齐地分配给变量。请考虑以下ES5代码： <blockquote> var voxel = {x：3.6，y：7.4，z：6.54}; <br> var x = voxel.x; // x = 3.6 <br> var y = voxel.y; // y = 7.4 <br> var z = voxel.z; // z = 6.54 </blockquote>这是与ES6解构语法相同的赋值语句： <blockquote> const {x，y，z} =体素; // x = 3.6，y = 7.4，z = 6.54 </blockquote>相反，如果你想将<code>voxel.x</code>的值存储到<code>a</code> ，将<code>voxel.y</code>到<code>b</code> ，将<code>voxel.z</code>到<code>c</code> ，那么你也有这种自由。 <blockquote> const {x：a，y：b，z：c} =体素// a = 3.6，b = 7.4，c = 6.54 </blockquote>您可以将其读作“获取字段<code>x</code>并将值复制到<code>a</code>中”，依此类推。 </section>
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## Instructions
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<section id="instructions">使用解构从输入对象<code>AVG_TEMPERATURES</code>获得明天的平均温度，并在<code>tomorrow</code>将关键值赋值给<code>tempOfTomorrow</code> 。 </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>getTempOfTmrw(AVG_TEMPERATURES)</code>应为<code>79</code>
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testString: 'assert(getTempOfTmrw(AVG_TEMPERATURES) === 79, "<code>getTempOfTmrw(AVG_TEMPERATURES)</code> should be <code>79</code>");'
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- text: 使用了重新分配的解构
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testString: 'getUserInput => assert(getUserInput("index").match(/\{\s*tomorrow\s*:\s*tempOfTomorrow\s*}\s*=\s*avgTemperatures/g),"destructuring with reassignment was used");'
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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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const AVG_TEMPERATURES = {
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today: 77.5,
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tomorrow: 79
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};
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function getTempOfTmrw(avgTemperatures) {
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"use strict";
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// change code below this line
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const tempOfTomorrow = undefined; // change this line
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// change code above this line
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return tempOfTomorrow;
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}
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console.log(getTempOfTmrw(AVG_TEMPERATURES)); // should be 79
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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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// solution required
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```
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</section>
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