89 lines
2.1 KiB
Markdown
89 lines
2.1 KiB
Markdown
---
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id: 599a789b454f2bbd91a3ff4d
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challengeType: 1
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videoUrl: 'https://scrimba.com/c/cm8PqCa'
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forumTopicId: 301174
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title: 比较不同值
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---
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## Description
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<section id='description'>
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在上两个挑战中，我们学习了相等运算符 (<code>==</code>) 和严格相等运算符 (<code>===</code>)。现在让我们快速回顾并实践一下。
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如果要比较的值不是同一类型，相等运算符会先执行数据类型转换，然后比较值。而严格相等运算符只比较值，不会进行数据类型转换。
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由此可见，相等运算符和严格相等运算符的区别是：前者会执行隐式类型转换，后者不会。
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<strong>示例</strong>
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```js
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3 == '3' // returns true because JavaScript performs type conversion from string to number
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3 === '3' // returns false because the types are different and type conversion is not performed
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```
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<strong>提示</strong><br>在JavaScript中，你可以使用<code>typeof</code>运算符确定变量的类型或值，如下所示：
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```js
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typeof 3 // returns 'number'
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typeof '3' // returns 'string'
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```
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</section>
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## Instructions
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<section id='instructions'>
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编辑器中的<code>compareEquality</code>函数使用相等运算符比较两个值。修改函数，使其仅在值严格相等时返回 "Equal" 。
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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>compareEquality(10, "10")</code>应该返回 "Not Equal"。
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testString: assert(compareEquality(10, "10") === "Not Equal");
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- text: <code>compareEquality("20", 20)</code>应该返回 "Not Equal"。
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testString: assert(compareEquality("20", 20) === "Not Equal");
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- text: 你应该使用<code>===</code>运算符。
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testString: assert(code.match(/===/g));
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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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function compareEquality(a, b) {
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if (a == b) { // Change this line
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return "Equal";
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}
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return "Not Equal";
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}
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// Change this value to test
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compareEquality(10, "10");
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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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function compareEquality(a,b) {
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if (a === b) {
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return "Equal";
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}
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return "Not Equal";
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}
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```
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</section>
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