81 lines
3.0 KiB
Markdown
81 lines
3.0 KiB
Markdown
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---
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id: 587d7db0367417b2b2512b83
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title: Use Inheritance So You Don't Repeat Yourself
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challengeType: 1
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videoUrl: ''
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localeTitle: 使用继承，所以你不要重复自己
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---
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## Description
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<section id="description">编程中有一个原则叫做“ <code>Don't Repeat Yourself (DRY)</code> 。重复代码是一个问题的原因是因为任何更改都需要在多个位置修复代码。这通常意味着为程序员提供更多工作，并且有更多错误空间。请注意，在下面的示例中， <code>describe</code>方法由<code>Bird</code>和<code>Dog</code>共享： <blockquote> Bird.prototype = { <br>构造函数：Bird， <br> describe：function（）{ <br> console.log（“我的名字是”+ this.name）; <br> } <br> }; <br><br> Dog.prototype = { <br>构造函数：狗， <br> describe：function（）{ <br> console.log（“我的名字是”+ this.name）; <br> } <br> }; </blockquote> <code>describe</code>方法在两个地方重复。可以通过创建名为<code>Animal</code>的<code>supertype</code> （或父级）来编辑代码以遵循<code>DRY</code>原则： <blockquote> function Animal（）{}; <br><br> Animal.prototype = { <br>构造函数：Animal， <br> describe：function（）{ <br> console.log（“我的名字是”+ this.name）; <br> } <br> }; </blockquote>由于<code>Animal</code>包含<code>describe</code>方法，您可以从<code>Bird</code>和<code>Dog</code>删除它： <blockquote> Bird.prototype = { <br>构造函数：Bird <br> }; <br><br> Dog.prototype = { <br>构造函数：狗<br> }; </blockquote></section>
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## Instructions
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<section id="instructions"> <code>Cat</code>和<code>Bear</code>都重复<code>eat</code> 。通过将<code>eat</code>方法移动到<code>Animal</code> <code>supertype</code>以<code>DRY</code>的精神编辑代码。 </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>Animal.prototype</code>应该有<code>eat</code>属性。
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testString: 'assert(Animal.prototype.hasOwnProperty("eat"), "<code>Animal.prototype</code> should have the <code>eat</code> property.");'
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- text: <code>Bear.prototype</code>不应该有<code>eat</code>属性。
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testString: 'assert(!(Bear.prototype.hasOwnProperty("eat")), "<code>Bear.prototype</code> should not have the <code>eat</code> property.");'
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- text: <code>Cat.prototype</code>不应该有<code>eat</code>属性。
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testString: 'assert(!(Cat.prototype.hasOwnProperty("eat")), "<code>Cat.prototype</code> should not have the <code>eat</code> property.");'
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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 Cat(name) {
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this.name = name;
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}
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Cat.prototype = {
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constructor: Cat,
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eat: function() {
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console.log("nom nom nom");
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}
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};
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function Bear(name) {
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this.name = name;
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}
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Bear.prototype = {
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constructor: Bear,
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eat: function() {
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console.log("nom nom nom");
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}
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};
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function Animal() { }
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Animal.prototype = {
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constructor: Animal,
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};
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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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