65 lines
1.7 KiB
Markdown
65 lines
1.7 KiB
Markdown
---
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id: 56533eb9ac21ba0edf2244ba
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title: Understand String Immutability
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challengeType: 1
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videoUrl: ''
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localeTitle: 理解字符串不变性
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---
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## Description
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<section id="description">在JavaScript中， <code>String</code>值是<dfn>不可变的</dfn> ，这意味着一旦创建它们就不能被更改。例如，以下代码： <blockquote> var myStr =“Bob”; <br> myStr [0] =“J”; </blockquote>无法将<code>myStr</code>的值更改为“Job”，因为<code>myStr</code>的内容无法更改。请注意，这<em>并不</em>意味着<code>myStr</code>不能改变的，只是一个<dfn>字符串</dfn>的单个字符不能改变。更改<code>myStr</code>的唯一方法是为其分配一个新字符串，如下所示： <blockquote> var myStr =“Bob”; <br> myStr =“工作”; </blockquote></section>
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## Instructions
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<section id="instructions">更正<code>myStr</code>的赋值，使其包含<code>Hello World</code>的字符串值，使用上面示例中显示的方法。 </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>myStr</code>应该具有<code>Hello World</code>的值
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testString: 'assert(myStr === "Hello World", "<code>myStr</code> should have a value of <code>Hello World</code>");'
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- text: 不要更改行上方的代码
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testString: 'assert(/myStr = "Jello World"/.test(code), "Do not change the code above the line");'
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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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// Setup
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var myStr = "Jello World";
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// Only change code below this line
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myStr[0] = "H"; // Fix Me
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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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