70 lines
3.1 KiB
Markdown
70 lines
3.1 KiB
Markdown
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---
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id: 587d7b88367417b2b2512b45
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title: Write Higher Order Arrow Functions
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challengeType: 1
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videoUrl: ''
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localeTitle: 编写高阶箭头函数
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---
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## Description
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<section id="description">是时候我们看到处理数据时箭头功能有多强大了。 Arrow函数与高阶函数（例如<code>map()</code> ， <code>filter()</code>和<code>reduce()</code>非常兼容，它们将其他函数作为处理数据集合的参数。阅读以下代码： <blockquote> FBPosts.filter（function（post）{ <br> return post.thumbnail！== null && post.shares> 100 && post.likes> 500; <br> }） </blockquote>我们用<code>filter()</code>写了这个，至少使它有点可读。现在将它与以下使用箭头函数语法的代码进行比较： <blockquote> FBPosts.filter（（post）=> post.thumbnail！== null && post.shares> 100 && post.likes> 500） </blockquote>此代码更简洁，使用更少的代码行完成相同的任务。 </section>
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## Instructions
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<section id="instructions">使用箭头函数语法计算数组<code>realNumberArray</code>中只有正整数（十进制数不是整数）的<code>realNumberArray</code> ，并将新数组存储在变量<code>squaredIntegers</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>squaredIntegers</code>应该是一个常量变量（通过使用<code>const</code> ）。
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testString: 'getUserInput => assert(getUserInput("index").match(/const\s+squaredIntegers/g), "<code>squaredIntegers</code> should be a constant variable (by using <code>const</code>).");'
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- text: <code>squaredIntegers</code>应该是一个<code>array</code>
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testString: 'assert(Array.isArray(squaredIntegers), "<code>squaredIntegers</code> should be an <code>array</code>");'
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- text: '<code>squaredIntegers</code>应该是<code>[16, 1764, 36]</code> <code>squaredIntegers</code> <code>[16, 1764, 36]</code>'
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testString: 'assert.deepStrictEqual(squaredIntegers, [16, 1764, 36], "<code>squaredIntegers</code> should be <code>[16, 1764, 36]</code>");'
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- text: <code>function</code>关键字未使用。
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testString: 'getUserInput => assert(!getUserInput("index").match(/function/g), "<code>function</code> keyword was not used.");'
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- text: 不应该使用循环
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testString: 'getUserInput => assert(!getUserInput("index").match(/(for)|(while)/g), "loop should not be used");'
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- text: 应使用<code>map</code> ， <code>filter</code>或<code>reduce</code>
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testString: 'getUserInput => assert(getUserInput("index").match(/map|filter|reduce/g), "<code>map</code>, <code>filter</code>, or <code>reduce</code> should be 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 realNumberArray = [4, 5.6, -9.8, 3.14, 42, 6, 8.34, -2];
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const squareList = (arr) => {
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"use strict";
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// change code below this line
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const squaredIntegers = arr;
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// change code above this line
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return squaredIntegers;
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};
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// test your code
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const squaredIntegers = squareList(realNumberArray);
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console.log(squaredIntegers);
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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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