57 lines
2.2 KiB
Markdown
57 lines
2.2 KiB
Markdown
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---
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id: 587d7dad367417b2b2512b78
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title: Use a Constructor to Create Objects
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challengeType: 1
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videoUrl: ''
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localeTitle: 使用构造函数创建对象
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---
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## Description
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<section id="description">这是上一次挑战中的<code>Bird</code>构造函数： <blockquote> function Bird（）{ <br> this.name =“阿尔伯特”; <br> this.color =“blue”; <br> this.numLegs = 2; <br> //构造函数中的“this”始终引用正在创建的对象<br> } <br><br>让blueBird = new Bird（）; </blockquote>请注意，在调用构造函数时使用<code>new</code>运算符。这告诉JavaScript创建一个名为<code>blueBird</code>的<code>Bird</code>新<code>instance</code> 。如果没有<code>new</code>运营商， <code>this</code>在构造函数中不会指向新创建的对象，给人意想不到的效果。现在， <code>blueBird</code>具有在<code>Bird</code>构造函数中定义的所有属性： <blockquote> blueBird.name; // =>艾伯特<br> blueBird.color; // =>蓝色<br> blueBird.numLegs; // => 2 </blockquote>就像任何其他对象一样，可以访问和修改其属性： <blockquote> blueBird.name ='Elvira'; <br> blueBird.name; // =>埃尔维拉</blockquote></section>
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## Instructions
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<section id="instructions">使用上一课中的<code>Dog</code>构造函数创建<code>Dog</code>的新实例，将其分配给变量<code>hound</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: 应该使用<code>Dog</code>构造函数创建<code>hound</code> 。
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testString: 'assert(hound instanceof Dog, "<code>hound</code> should be created using the <code>Dog</code> constructor.");'
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- text: 您的代码应该使用<code>new</code>运算符来创建<code>Dog</code>的<code>instance</code> 。
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testString: 'assert(code.match(/new/g), "Your code should use the <code>new</code> operator to create an <code>instance</code> of <code>Dog</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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function Dog() {
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this.name = "Rupert";
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this.color = "brown";
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this.numLegs = 4;
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}
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// Add your code below this line
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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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