Javascript（ES6）const带花括号 [英] Javascript (ES6) const with curly braces

问题描述

我是ECMAScript 6的新手，而在尝试学习Ember的时候，我有时会看到以下代码样式：

  const {
 abc，
 def 
} = Object; 
  

我已经搜索了Google和许多网站，解释了新的ES6规范。我知道这不是当前的实现，因为我的控制台输入时出现错误。

这段代码是什么意思？

更新

我将此代码段粘贴到 Babel's transpiler ，这是它返回的：

 use strict; 
 
 var abc = Object.abc; 
 var def = Object.def; 
  

我仍然感到困惑，这是为了完成这件事。

解决方案

它是一个ES2015 解构任务。

它可能有助于看到它以更详细的方式重写。

  const abc = Object.abc; 
 const def = Object.def; 
  

这是从对象提取属性到变量的一种简洁的方法。

  //你可以重写这个
 const name = app.name; 
 const version = app.version; 
 const type = app.type; 
 
 // as 
 const {name，version，type} = app; 
  

浏览器供应商是仍然实现了ES2015规范，这可能是为什么它在浏览器中不起作用。

但是，有一个名为 Babel 的项目可让您将未来的Javascript规范转换回来进入ES5。您可以在他们的REPL 中尝试ES2015代码。

I'm new to ECMAScript 6, and while trying to learn Ember, I've seen the following code style occassionally:

const {
  abc,
  def
} = Object;

I've searched Google and many sites explaining the new ES6 specifications. I know this is not the current implementation, because my console gives an error when I input that.

What does this code mean?

UPDATE

I pasted this snippet into Babel's transpiler, and this is what it returned:

"use strict";

var abc = Object.abc;
var def = Object.def;

I'm still confused as to what this is trying to accomplish.

解决方案

It is an ES2015 destructuring assignment.

It might help to see it rewritten in a more verbose way.

const abc = Object.abc;
const def = Object.def;

It's a syntatically terse way of extracting properties from objects, into variables.

// you can rewrite this
const name = app.name;
const version = app.version;
const type = app.type;

// as this
const { name, version, type } = app;

Browser vendors are still implementing the ES2015 specification which is probably why it didn't work in your browser.

However, there's a project called Babel which allows you to convert future specifications of Javascript back into ES5. You can try out ES2015 code in their REPL.

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