65 lines
1.6 KiB
Markdown
65 lines
1.6 KiB
Markdown
---
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title: Destructuring Assignment
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localeTitle: 解构分配
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---
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## 解构分配
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Destructuring Assignment语法是一个Javascript表达式，可以从数组或对象中解压缩值或属性。
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假设您有一个包含名字和姓氏的数组，因为它是两个值，但您希望将这些值重新分配给更具描述性的值。您可以使用Destructuring来完成此任务。
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**ES5解构**
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```js
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var fullName = ["John", "Smith"];
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var firstName = fullName[0];
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var lastName = fullName[1];
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console.log(firstName, lastName); // John Smith
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```
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**ES6解构**
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```js
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const fullName = ["John", "Smith"];
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const [firstName, lastName] = fullName;
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console.log(firstName, lastName); // John Smith
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```
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上面的示例显示了使用ES6 Destructuring Assignment的好处。
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您还可以使用类似语法在对象上使用Destructuring
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```js
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const fullName = { first: "John", last: "Smith"};
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const {first, last} = fullName;
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console.log(first, last); // John Smith
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```
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对象解析分配略有不同，因为对象必须具有您要分配的名称的属性。因此，下面的代码不会按预期工作。
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```js
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const fullName = { first: "John", last: "Smith"};
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const {firstName, lastName} = fullName;
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console.log(firstName, lastName); // undefined undefined
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```
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您仍然可以使用以下语法获得所需的结果。
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```js
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const obj = {propertyName: value}
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{propertyName: desiredVariableName} = obj
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```
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我们之前的例子将被重写如下：
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```js
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const fullName = { first: "John", last: "Smith"};
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const {first: firstName, last: lastName} = fullName;
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console.log(firstName, lastName); // John Smith
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``` |