• ES-discuss mailing list (Preparation for the TC39 Process)

Subject: Destructuring into object

If you assign via destructuring, each assignment target can be everything that is allowed on the left side of a normal assignment.

  let srcObject = {a:1,b:2,c:3}, target = {};     
  
  ({a: target.a} = srcObject);  
  
  console.log(target); // {a:1}

(You can assign to more than just variables)

The Problem

ES6 destructuring syntax isn't very readable and useful, in case with assigning to properties of existing object:

	// ES6
	({
	    a: target.a,
	    b: target.b,
	    c: target.c,
	} = srcObject);
	
	// Versus ES3
	target.a = srcObject.a;
	target.b = srcObject.b;
	target.c = srcObject.c;

There is no reasons to start using new ES6 destructuring syntax now, old syntax is better, because:

• there is hard to assume that target object will be modified, if developer does not familar with new standart
• identifiers are still duplicated
• you should write braces () or use other solution, because JS statement cannot starts with {

Proposal

So, in addition to current ES6 syntax, I want to propose this sugar:

	target.{a,b,c} = srcObject
	//alternative// target.* = srcObject{a,b,c}

Why?

• This syntax is more clear and understandable:
  even without ES6 knowleges, developer can assume that some properties assigned to the left-side target from a right-side srcObject variable.
• The one of destructuring goal is met: full elimination of identifiers duplication.
• You can omit braces () because JS statement doesn't starts with { now.

New syntax for Object.assign()

	let target = {a:0}
	
	target.* = {b:1, c:2}
	//alternative// target.{} = ...
	
	console.log(target) // {a:0, b:1, c:2}	

Useful for:

• adding properties to the this object in constructor
• adding methods to the prototype of class

Extracting properties into local variables

	let * = {a:1, b:2} // like import * from 'module'
	console.log(a, b) // 1 2

Babel plugin

Please star, to start) And I will create babel plugin.