ee1e8abd87
* feat(tools): add seed/solution restore script * chore(curriculum): remove empty sections' markers * chore(curriculum): add seed + solution to Chinese * chore: remove old formatter * fix: update getChallenges parse translated challenges separately, without reference to the source * chore(curriculum): add dashedName to English * chore(curriculum): add dashedName to Chinese * refactor: remove unused challenge property 'name' * fix: relax dashedName requirement * fix: stray tag Remove stray `pre` tag from challenge file. Signed-off-by: nhcarrigan <nhcarrigan@gmail.com> Co-authored-by: nhcarrigan <nhcarrigan@gmail.com>
98 lines
1.9 KiB
Markdown
98 lines
1.9 KiB
Markdown
---
|
|
id: 5cfa550e84205a357704ccb6
|
|
title: 使用解构赋值来获取对象的值
|
|
challengeType: 1
|
|
forumTopicId: 301216
|
|
dashedName: use-destructuring-assignment-to-extract-values-from-objects
|
|
---
|
|
|
|
# --description--
|
|
|
|
<dfn>解构赋值</dfn> 是 ES6 引入的新语法，用来从数组和对象中提取值，并优雅的对变量进行赋值。
|
|
|
|
有如下 ES5 代码：
|
|
|
|
```js
|
|
const user = { name: 'John Doe', age: 34 };
|
|
|
|
const name = user.name; // name = 'John Doe'
|
|
const age = user.age; // age = 34
|
|
```
|
|
|
|
下面是使用 ES6 解构赋值的等价语句：
|
|
|
|
```js
|
|
const { name, age } = user;
|
|
// name = 'John Doe', age = 34
|
|
```
|
|
|
|
在这里，`name` 和 `age` 被自动创建并赋予 `user` 对象相应属性的值。一目了然。
|
|
|
|
解构赋值的参数数量可以任意。
|
|
|
|
# --instructions--
|
|
|
|
把两个赋值语句替换成等价的解构赋值。`today` 和 `tomorrow` 的值应该还为 `HIGH_TEMPERATURES` 对象的 `today` 和 `tomorrow` 属性的值。
|
|
|
|
# --hints--
|
|
|
|
应该移除 ES5 赋值语句。
|
|
|
|
```js
|
|
assert(
|
|
!code.match(/today = HIGH_TEMPERATURES\.today/g) &&
|
|
!code.match(/tomorrow = HIGH_TEMPERATURES\.tomorrow/g)
|
|
);
|
|
```
|
|
|
|
应该解构创建 `today` 变量。
|
|
|
|
```js
|
|
assert(
|
|
code.match(
|
|
/(var|let|const)\s*{\s*(today[^}]*|[^,]*,\s*today)\s*}\s*=\s*HIGH_TEMPERATURES(;|\s+|\/\/)/g
|
|
)
|
|
);
|
|
```
|
|
|
|
应该解构创建 `tomorrow` 变量。
|
|
|
|
```js
|
|
assert(
|
|
code.match(
|
|
/(var|let|const)\s*{\s*(tomorrow[^}]*|[^,]*,\s*tomorrow)\s*}\s*=\s*HIGH_TEMPERATURES(;|\s+|\/\/)/g
|
|
)
|
|
);
|
|
```
|
|
|
|
# --seed--
|
|
|
|
## --seed-contents--
|
|
|
|
```js
|
|
const HIGH_TEMPERATURES = {
|
|
yesterday: 75,
|
|
today: 77,
|
|
tomorrow: 80
|
|
};
|
|
|
|
// Only change code below this line
|
|
|
|
const today = HIGH_TEMPERATURES.today;
|
|
const tomorrow = HIGH_TEMPERATURES.tomorrow;
|
|
|
|
// Only change code above this line
|
|
```
|
|
|
|
# --solutions--
|
|
|
|
```js
|
|
const HIGH_TEMPERATURES = {
|
|
yesterday: 75,
|
|
today: 77,
|
|
tomorrow: 80
|
|
};
|
|
|
|
const { today, tomorrow } = HIGH_TEMPERATURES;
|
|
```
|