创建一个子对象，只包含现有对象的一些属性 [英] Create a subset object, consisting of only some of the properties of an existing object

问题描述

这个例子最好的解释。以下作品在es6中创建一个由现有对象的一些键组成的对象：

  var o = {a：1，b：2，c：3} 
 var {a，c} = o 
 var subsetObj = {a，c} //将是：{a： 1，c：3} 
  

这里有两个缺点：

1. 它需要两条命令，两条线来创建所需的子集对象


2. 我们必须通过创建本地变量范围来污染本地变量范围中间人 a 和 c 变量，这些变量不需要在本地，除非是创建我们的子集对象的手段。 / li>
   

有没有办法在单个语句中完成相同的事情，而不会引入不必要的本地人 a 和 c ？

解决方案

这个的语法。你可以继续做：

  var subsetObj = {a：o.a，c：o.c}; 
  

如果您有更多属性或可变数量的属性，请创建一个帮助函数。

相关：是否可以重建到现有对象？ （Javascript ES6）

This is best explained by example. The following works in es6 to create an object consisting of some of the keys of an existing object:

var o = {a:1, b: 2, c: 3}
var {a, c} = o
var subsetObj = {a, c} // will be: {a:1, c:3}

There are two downsides here:

1. It took two statments, and two lines, to create the desired subset object
2. We had to pollute the local variable scope by creating the intermediary a and c variables, which aren't needed locally, except as a means to creating our subset object.

Is there a way to accomplish the same thing in a single statement, without introducing the unnecessary locals a and c?

解决方案

There is no specific syntax for this. You can keep doing:

var subsetObj = {a: o.a, c: o.c};

If you have more properties or a variable number of properties, create a helper function.

Related: Is it possible to destructure onto an existing object? (Javascript ES6)

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