80 lines
1.7 KiB
Markdown
80 lines
1.7 KiB
Markdown
---
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id: 56533eb9ac21ba0edf2244ac
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title: Increment a Number with JavaScript
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challengeType: 1
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videoUrl: 'https://scrimba.com/c/ca8GLT9'
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forumTopicId: 18201
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localeTitle: 数字递增
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---
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## Description
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<section id='description'>
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使用<code>++</code>，我们可以很容易地对变量进行自增或者<code>+1</code>运算。
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<code>i++;</code>
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等效于
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<code>i = i + 1;</code>
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<strong>注意</strong><br><code>i++;</code>这种写法，省去了书写<code>=</code>符号的必要。
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</section>
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## Instructions
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<section id='instructions'>
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重写代码，使用<code>++</code>来对变量<code>myVar</code>进行自增操作。
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<strong>提示</strong><br>了解更多关于<code>++</code>运算符<a href="https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators#%E9%80%92%E5%A2%9E_()" target="_blank">Arithmetic operators - Increment (++)</a>.
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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>myVar</code>应该等于<code>88</code>。
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testString: assert(myVar === 88);
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- text: <code>myVar = myVar + 1;</code>语句应该被修改。
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testString: assert(/var\s*myVar\s*=\s*87;\s*\/*.*\s*myVar\+\+;/.test(code));
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- text: 使用<code>++</code>运算符。
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testString: assert(/[+]{2}\s*myVar|myVar\s*[+]{2}/.test(code));
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- text: 不要修改注释上方的代码。
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testString: assert(/var myVar = 87;/.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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var myVar = 87;
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// Only change code below this line
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myVar = myVar + 1;
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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(z){return 'myVar = ' + z;})(myVar);
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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 myVar = 87;
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myVar++;
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```
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</section>
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