ES6结构分配？ [英] ES6 Structuring Assignment?

问题描述

ES6 的新的解构任务功能现在已经很熟悉了（现场副本在Babel的REPL上）;在存在的变量的情况下：

The new destructuring assignment features of ES6 are fairly well known now (live copy on Babel's REPL); in the case of variables that already exist:

let a, b;                 // Existing variables
let o = {a: "a", b: "b"}; // An object to get values from
// ...
({a, b} = o);             // Set them to the props from `o`
console.log(a);           // "a"
console.log(b);           // "b"

ES6中是否有一个简单的相反？基于具有相同名称的变量，在现有对象上设置属性？ （除了明显的 oa = a; ob = b; ）

Is there a simple converse in ES6? Setting properties on an existing object based on variables with the same name? (Other than the obvious o.a = a; o.b = b;)

注意我不是在说什么创建一个对象，我们可以通过美妙的新对象初始化器语法来实现，不用重复这些名称：

Note I'm not talking about when creating an object, we could do that with the wonderful new object initializer syntax that lets us not repeat the names unnecessarily:

let a = "a";
let b = "b";
let o = {a, b};

但是如果我已经有一个对象，我可以做某种

But if I already have an object, can I do some kind of structuring assignment in ES6?

推荐答案

最近我想出的是使用 Object.assign 和一个临时对象（现场副本）：

The closest I've come up with is to use Object.assign and a temporary object (live copy):

let a = "a", b = "b";             // The variables
let obj = {c: "c"};               // The existing object
Object.assign(obj, {a, b});       // "Structuring" assignment, sort of
console.log(JSON.stringify(obj)); // "{"c":"c","a":"a","b":"b"}

这很简单，但它是一个函数调用和一个临时对象。

It's fairly simple, but it's a function call and a temporary object.

更新： Bergi 指出在评论中有一个用于执行此操作的：= 操作符的草稿提案，其中第一个用例之一确实是主要使用此问题的用例：构造函数：

Update: Bergi points out in a comment that there's a strawman proposal for a := operator that will do this, and one of their first use cases is indeed the use case that primarily lead me to this question: Constructors:

// From strawman proposal linked above, doesn't actually exist yet!
class Point {
   constructor(x,y) {
      this := {x,y}  //define and initialize x and y properties of new object
      //   ^^
   }
}

因此，鉴于这个秸秆存在，我怀疑现在，这个分配将是我在ES6中能做的最好的。

So given that strawman exists, I suspect for now the assign is going to be the best I can do in ES6.

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