2018-10-10 18:03:03 -04:00
|
|
|
|
---
|
|
|
|
|
id: bd7123c9c441eddfaeb5bdef
|
2020-12-16 00:37:30 -07:00
|
|
|
|
title: 理解布尔值
|
2018-10-10 18:03:03 -04:00
|
|
|
|
challengeType: 1
|
2020-04-29 18:29:13 +08:00
|
|
|
|
videoUrl: 'https://scrimba.com/c/c9Me8t4'
|
|
|
|
|
forumTopicId: 301176
|
2021-01-13 03:31:00 +01:00
|
|
|
|
dashedName: understanding-boolean-values
|
2018-10-10 18:03:03 -04:00
|
|
|
|
---
|
|
|
|
|
|
2020-12-16 00:37:30 -07:00
|
|
|
|
# --description--
|
2018-10-10 18:03:03 -04:00
|
|
|
|
|
2020-12-16 00:37:30 -07:00
|
|
|
|
另一种数据类型是<dfn>布尔</dfn>(Boolean)。`布尔`值要么是`true`要么是`false`。它非常像电路开关,`true`是 “开”,`false`是 “关”。这两种状态是互斥的。
|
2018-10-10 18:03:03 -04:00
|
|
|
|
|
2020-12-16 00:37:30 -07:00
|
|
|
|
**注意**
|
|
|
|
|
`布尔值`是不带引号的,`"true"`和`"false"`是`字符串`而不是`布尔值`,在 JavaScript 中也没有特殊含义。
|
2018-10-10 18:03:03 -04:00
|
|
|
|
|
2020-12-16 00:37:30 -07:00
|
|
|
|
# --instructions--
|
2018-10-10 18:03:03 -04:00
|
|
|
|
|
2020-12-16 00:37:30 -07:00
|
|
|
|
修改`welcomeToBooleans`函数,让它返回`true`而不是`false`。
|
2018-10-10 18:03:03 -04:00
|
|
|
|
|
2020-12-16 00:37:30 -07:00
|
|
|
|
# --hints--
|
2018-10-10 18:03:03 -04:00
|
|
|
|
|
2020-12-16 00:37:30 -07:00
|
|
|
|
`welcomeToBooleans()`函数应该返回一个布尔值 (true/false)。
|
2018-10-10 18:03:03 -04:00
|
|
|
|
|
|
|
|
|
```js
|
2020-12-16 00:37:30 -07:00
|
|
|
|
assert(typeof welcomeToBooleans() === 'boolean');
|
2018-10-10 18:03:03 -04:00
|
|
|
|
```
|
|
|
|
|
|
2020-12-16 00:37:30 -07:00
|
|
|
|
`welcomeToBooleans()`应该返回 true。
|
2018-10-10 18:03:03 -04:00
|
|
|
|
|
|
|
|
|
```js
|
2020-12-16 00:37:30 -07:00
|
|
|
|
assert(welcomeToBooleans() === true);
|
2018-10-10 18:03:03 -04:00
|
|
|
|
```
|
|
|
|
|
|
2021-01-13 03:31:00 +01:00
|
|
|
|
# --seed--
|
|
|
|
|
|
|
|
|
|
## --after-user-code--
|
|
|
|
|
|
|
|
|
|
```js
|
|
|
|
|
welcomeToBooleans();
|
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
## --seed-contents--
|
|
|
|
|
|
|
|
|
|
```js
|
|
|
|
|
function welcomeToBooleans() {
|
|
|
|
|
|
|
|
|
|
// Only change code below this line
|
|
|
|
|
|
|
|
|
|
return false; // Change this line
|
|
|
|
|
|
|
|
|
|
// Only change code above this line
|
|
|
|
|
}
|
|
|
|
|
```
|
|
|
|
|
|
2020-12-16 00:37:30 -07:00
|
|
|
|
# --solutions--
|
2020-04-29 18:29:13 +08:00
|
|
|
|
|
2021-01-13 03:31:00 +01:00
|
|
|
|
```js
|
|
|
|
|
function welcomeToBooleans() {
|
|
|
|
|
return true; // Change this line
|
|
|
|
|
}
|
|
|
|
|
```
|