2018-10-10 18:03:03 -04:00
|
|
|
|
---
|
|
|
|
|
id: 56533eb9ac21ba0edf2244d0
|
|
|
|
|
title: Comparison with the Equality Operator
|
|
|
|
|
challengeType: 1
|
|
|
|
|
videoUrl: ''
|
|
|
|
|
localeTitle: 与平等算子的比较
|
|
|
|
|
---
|
|
|
|
|
|
|
|
|
|
## Description
|
|
|
|
|
<section id="description">有很多<dfn>比较运算符</dfn>在JavaScript中。所有这些运算符都返回布尔值<code>true</code>或<code>false</code>值。最基本的运算符是等于运算符<code>==</code> 。等于运算符比较两个值,如果它们是等价的则返回<code>true</code>否则返回<code>false</code> 。请注意,相等性与赋值( <code>=</code> )不同,后者将运算符右侧的值分配给左侧的变量。 <blockquote> function equalityTest(myVal){ <br> if(myVal == 10){ <br>返回“平等”; <br> } <br>返回“不等于”; <br> } </blockquote>如果<code>myVal</code>等于<code>10</code> ,则等于运算符返回<code>true</code> ,因此大括号中的代码将执行,函数将返回<code>"Equal"</code> 。否则,该函数将返回<code>"Not Equal"</code> 。为了使JavaScript能够比较两种不同的<code>data types</code> (例如, <code>numbers</code>和<code>strings</code> ),它必须将一种类型转换为另一种类型。这被称为“类型强制”。但是,一旦它完成,它可以比较如下术语: <blockquote> 1 == 1 //是的<br> 1 == 2 //假<br> 1 =='1'//是的<br> “3”== 3 //是的</blockquote></section>
|
|
|
|
|
|
|
|
|
|
## Instructions
|
|
|
|
|
<section id="instructions">将<code>equality operator</code>添加到指示的行,以便当<code>val</code>等于<code>12</code>时,函数将返回“Equal” </section>
|
|
|
|
|
|
|
|
|
|
## Tests
|
|
|
|
|
<section id='tests'>
|
|
|
|
|
|
|
|
|
|
```yml
|
|
|
|
|
tests:
|
|
|
|
|
- text: <code>testEqual(10)</code>应该返回“Not Equal”
|
2020-02-18 01:40:55 +09:00
|
|
|
|
testString: assert(testEqual(10) === "Not Equal");
|
2018-10-10 18:03:03 -04:00
|
|
|
|
- text: <code>testEqual(12)</code>应返回“Equal”
|
2020-02-18 01:40:55 +09:00
|
|
|
|
testString: assert(testEqual(12) === "Equal");
|
2018-10-10 18:03:03 -04:00
|
|
|
|
- text: <code>testEqual("12")</code>应返回“Equal”
|
2020-02-18 01:40:55 +09:00
|
|
|
|
testString: assert(testEqual("12") === "Equal");
|
2018-10-10 18:03:03 -04:00
|
|
|
|
- text: 您应该使用<code>==</code>运算符
|
2020-02-18 01:40:55 +09:00
|
|
|
|
testString: assert(code.match(/==/g) && !code.match(/===/g));
|
2018-10-10 18:03:03 -04:00
|
|
|
|
|
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
</section>
|
|
|
|
|
|
|
|
|
|
## Challenge Seed
|
|
|
|
|
<section id='challengeSeed'>
|
|
|
|
|
|
|
|
|
|
<div id='js-seed'>
|
|
|
|
|
|
|
|
|
|
```js
|
|
|
|
|
// Setup
|
|
|
|
|
function testEqual(val) {
|
|
|
|
|
if (val) { // Change this line
|
|
|
|
|
return "Equal";
|
|
|
|
|
}
|
|
|
|
|
return "Not Equal";
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
// Change this value to test
|
|
|
|
|
testEqual(10);
|
|
|
|
|
|
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
</section>
|
|
|
|
|
|
|
|
|
|
## Solution
|
|
|
|
|
<section id='solution'>
|
|
|
|
|
|
|
|
|
|
```js
|
|
|
|
|
// solution required
|
|
|
|
|
```
|
|
|
|
|
</section>
|