67 lines
1.8 KiB
Markdown
67 lines
1.8 KiB
Markdown
|
---
|
|||
|
|
id: bd7123c9c441eddfaeb5bdef
|
|||
|
|
title: Understanding Boolean Values
|
|||
|
|
challengeType: 1
|
|||
|
|
videoUrl: ''
|
|||
|
|
localeTitle: 了解布尔值
|
|||
|
|
---
|
|||
|
|
|
|||
|
|
## Description
|
|||
|
|
<section id="description">另一种数据类型是<dfn>布尔值</dfn> 。 <code>Booleans</code>可能只是两个值中的一个： <code>true</code>或<code>false</code> 。它们基本上是很少的开关，其中<code>true</code>为“on”而<code>false</code>为“off”。这两个国家是相互排斥的。 <strong>注意</strong> <br> <code>Boolean</code>值永远不会用引号写。 <code>strings</code> <code>"true"</code>和<code>"false"</code>不是<code>Boolean</code> ，在JavaScript中没有特殊含义。 </section>
|
|||
|
|
|
|||
|
|
## Instructions
|
|||
|
|
<section id="instructions">修改<code>welcomeToBooleans</code>函数，以便在单击运行按钮时返回<code>true</code>而不是<code>false</code> 。 </section>
|
|||
|
|
|
|||
|
|
## Tests
|
|||
|
|
<section id='tests'>
|
|||
|
|
|
|||
|
|
```yml
|
|||
|
|
tests:
|
|||
|
|
- text: <code>welcomeToBooleans()</code>函数应该返回一个布尔值（true / false）。
|
|||
|
|
testString: 'assert(typeof welcomeToBooleans() === "boolean", "The <code>welcomeToBooleans()</code> function should return a boolean (true/false) value.");'
|
|||
|
|
- text: <code>welcomeToBooleans()</code>应该返回true。
|
|||
|
|
testString: 'assert(welcomeToBooleans() === true, "<code>welcomeToBooleans()</code> should return true.");'
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
</section>
|
|||
|
|
|
|||
|
|
## Challenge Seed
|
|||
|
|
<section id='challengeSeed'>
|
|||
|
|
|
|||
|
|
<div id='js-seed'>
|
|||
|
|
|
|||
|
|
```js
|
|||
|
|
function welcomeToBooleans() {
|
|||
|
|
|
|||
|
|
// Only change code below this line.
|
|||
|
|
|
|||
|
|
return false; // Change this line
|
|||
|
|
|
|||
|
|
// Only change code above this line.
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
|
|||
|
|
### After Test
|
|||
|
|
<div id='js-teardown'>
|
|||
|
|
|
|||
|
|
```js
|
|||
|
|
console.info('after the test');
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
</section>
|
|||
|
|
|
|||
|
|
## Solution
|
|||
|
|
<section id='solution'>
|
|||
|
|
|
|||
|
|
```js
|
|||
|
|
// solution required
|
|||
|
|
```
|
|||
|
|
</section>
|