add one object to another object in javascript

Question

I have 2 objects, and I need to add one object to the other object.

var loc = {
  leftArray: [],
  topArray: [],
  bottomArray: [],
  rightArray: []
}

var obj = {
  id: "ce",
  icon: "logo/image.png",
  name: "CE",
  type: "type2",
  version: 3.4
}

var obj = {
  id: "ce",
  icon: "logo/image.png",
  name: "CE",
  type: "type2",
  version: 3.4,
  leftArray: [],
  topArray: [],
  bottomArray: [],
  rightArray: []
}

Is there any simple way to do this?

Perhaps you're looking for [`Object.assign()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign) — Pointy, Aug 24 '18 at 12:41
you can also use merge from lodash, if you have that lib... https://lodash.com/docs/#merge — devtye, Aug 24 '18 at 12:48
use like obj.leftArray=[]; which automatically generate new obj. — mittal bhatt, Aug 24 '18 at 12:53

score 6 · Accepted Answer · 2018-08-24T14:25:42.123

6

You can do it with Object.assign();

obj = Object.assign(obj, loc);

or just

Object.assign(obj, loc);

as T.J. Crowder proposed in his comment.

edited Aug 24 '18 at 14:25

answered Aug 24 '18 at 12:43

Just FWIW, there's no need for the assignment in this case, just `Object.assign(obj, loc);` would be sufficient. (And you certainly wouldn't want the `var`, since `obj` is already declared.) – T.J. Crowder Aug 24 '18 at 13:07
@T.J.Crowder Yeah, you're right about not redeclaring the variable. I didn't know that you don't need to assign the result of Object.assign(). Thanks for the info. I edited my answer accordingly. – Aug 24 '18 at 14:25
`Object.assign` returns the first object you pass in. That's so you can pass in an object initializer ("literal"), like this: `const foo = Object.assign({}, something, blah);` That's just a one-liner version of `const foo = {}; Object.assign(foo, something);` Thanks for contributing, and welcome! – T.J. Crowder Aug 24 '18 at 14:32

score 2 · Answer 2 · edited Aug 24 '18 at 12:49

you can merge them using Spread syntax like

let objOne = { a: 'hi' }
let objTwo = { b: 'hello' }
let objOneAndTwo = { ...objOne, ...objTwo }; // { a: 'hi', b: 'hello' }

or by using Object assign:

let objOneAndTwo = Object.assign({}, a, b)

note that using this way if your objects would have properties with the same name priority will be with the most right object (in this example objectTwo)

additional info:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax

add one object to another object in javascript

2 Answers2

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