98 lines
2.1 KiB
Markdown
98 lines
2.1 KiB
Markdown
---
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id: 587d7b89367417b2b2512b49
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title: 使用解构赋值从对象中分配变量
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challengeType: 1
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forumTopicId: 301215
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dashedName: use-destructuring-assignment-to-assign-variables-from-objects
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---
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# --description--
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可以给解构的值赋予一个新的变量名， 通过在赋值的时候将新的变量名放在冒号后面来实现。
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还是以上个例子的对象来举例：
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```js
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const user = { name: 'John Doe', age: 34 };
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```
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这是指定新的变量名的例子：
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```js
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const { name: userName, age: userAge } = user;
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```
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你可以这么理解这段代码：获取 `user.name` 的值，将它赋给一个新的变量 `userName`，等等。 `userName` 的值将是字符串 `John Doe`，`userAge` 的值将是数字 `34`。
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# --instructions--
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使用解构赋值语句替换两个赋值语句。 将 `HIGH_TEMPERATURES` 的 `today` 和 `tomorrow` 的值赋值给 `highToday` 和 `highTomorrow`。
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# --hints--
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应该移除 ES5 赋值语句。
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```js
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assert(
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!code.match(/highToday = HIGH_TEMPERATURES\.today/g) &&
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!code.match(/highTomorrow = HIGH_TEMPERATURES\.tomorrow/g)
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);
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```
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应该使用解构赋值语句创建 `highToday` 变量。
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```js
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assert(
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code.match(
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/(var|const|let)\s*{\s*(today\s*:\s*highToday[^}]*|[^,]*,\s*today\s*:\s*highToday\s*)}\s*=\s*HIGH_TEMPERATURES(;|\s+|\/\/)/g
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)
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);
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```
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应该使用解构赋值语句创建 `highTomorrow` 变量。
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```js
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assert(
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code.match(
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/(var|const|let)\s*{\s*(tomorrow\s*:\s*highTomorrow[^}]*|[^,]*,\s*tomorrow\s*:\s*highTomorrow\s*)}\s*=\s*HIGH_TEMPERATURES(;|\s+|\/\/)/g
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)
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);
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```
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`highToday` 应该等于 `77`，`highTomorrow` 应该等于 `80`。
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```js
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assert(highToday === 77 && highTomorrow === 80);
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```
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# --seed--
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## --seed-contents--
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```js
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const HIGH_TEMPERATURES = {
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yesterday: 75,
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today: 77,
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tomorrow: 80
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};
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// Only change code below this line
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const highToday = HIGH_TEMPERATURES.today;
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const highTomorrow = HIGH_TEMPERATURES.tomorrow;
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// Only change code above this line
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```
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# --solutions--
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```js
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const HIGH_TEMPERATURES = {
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yesterday: 75,
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today: 77,
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tomorrow: 80
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};
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const { today: highToday, tomorrow: highTomorrow } = HIGH_TEMPERATURES;
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```
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