freeCodeCamp/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/es6/use-destructuring-assignment-to-extract-values-from-objects.md

id, challengeType, forumTopicId, title

id	challengeType	forumTopicId	title
5cfa550e84205a357704ccb6	1	301216	使用解构赋值来获取对象的值

Description

解构赋值 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：

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：

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。

Tests

tests:
  - text: 应该移除 ES5 赋值语句。
    testString: assert(!code.match(/today = HIGH_TEMPERATURES\.today/g) && !code.match(/tomorrow = HIGH_TEMPERATURES\.tomorrow/g))
  - text: 应该解构创建 <code>today</code> 变量。
    testString: assert(code.match(/(var|let|const)\s*{\s*(today[^}]*|[^,]*,\s*today)\s*}\s*=\s*HIGH_TEMPERATURES(;|\s+|\/\/)/g));
  - text: 应该解构创建 <code>tomorrow</code> 变量。
    testString: assert(code.match(/(var|let|const)\s*{\s*(tomorrow[^}]*|[^,]*,\s*tomorrow)\s*}\s*=\s*HIGH_TEMPERATURES(;|\s+|\/\/)/g));

Challenge Seed

const HIGH_TEMPERATURES = {
  yesterday: 75,
  today: 77,
  tomorrow: 80
};

// change code below this line

const today = HIGH_TEMPERATURES.today;
const tomorrow = HIGH_TEMPERATURES.tomorrow;

// change code above this line

console.log(yesterday) // should be not defined
console.log(today); // should be 77
console.log(tomorrow); // should be 80

Solution

const HIGH_TEMPERATURES = {
  yesterday: 75,
  today: 77,
  tomorrow: 80
};

// change code below this line

const { today, tomorrow } = HIGH_TEMPERATURES;

// change code above this line

console.log(yesterday) // should be not defined
console.log(today); // should be 77
console.log(tomorrow); // should be 80