75 lines
2.2 KiB
Markdown
75 lines
2.2 KiB
Markdown
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---
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id: 5675e877dbd60be8ad28edc6
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title: Iterate Through an Array with a For Loop
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challengeType: 1
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videoUrl: ''
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localeTitle: 使用For循环遍历数组
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---
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## Description
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<section id="description"> JavaScript中的一个常见任务是遍历数组的内容。一种方法是使用<code>for</code>循环。此代码将数组<code>arr</code>每个元素输出到控制台： <blockquote> var arr = [10,9,8,7,6]; <br> for（var i = 0; i <arr.length; i ++）{ <br> （ARR [I]）的console.log; <br> } </blockquote>请记住，数组具有从零开始的编号，这意味着数组的最后一个索引是长度 - 1.我们对此循环的<dfn>条件</dfn>是<code>i < arr.length</code> ，当<code>i</code>长度为1时停止。 </section>
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## Instructions
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<section id="instructions">声明并将变量<code>total</code>初始化为<code>0</code> 。使用<code>for</code>循环将<code>myArr</code>数组的每个元素的值添加到<code>total</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: 应声明<code>total</code>并初始化为0
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testString: 'assert(code.match(/var.*?total\s*=\s*0.*?;/), "<code>total</code> should be declared and initialized to 0");'
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- text: <code>total</code>应该等于20
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testString: 'assert(total === 20, "<code>total</code> should equal 20");'
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- text: 您应该使用<code>for</code>循环来遍历<code>myArr</code>
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testString: 'assert(code.match(/for\s*\(/g).length > 1 && code.match(/myArr\s*\[/), "You should use a <code>for</code> loop to iterate through <code>myArr</code>");'
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- text: 不要直接将<code>total</code>设置为20
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testString: 'assert(!code.match(/total[\s\+\-]*=\s*(\d(?!\s*[;,])|[1-9])/g), "Do not set <code>total</code> to 20 directly");'
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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 ourArr = [ 9, 10, 11, 12];
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var ourTotal = 0;
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for (var i = 0; i < ourArr.length; i++) {
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ourTotal += ourArr[i];
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}
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// Setup
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var myArr = [ 2, 3, 4, 5, 6];
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// Only change code below this line
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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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console.info('after the test');
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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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