How can I Merge two JavaScript objects?

Question

I have two JavaScript objects

a =  {"aa" : "foo"}
b = {"b" : "bar"}

I want to concat both and want to get this result

result =  {"aa" : "foo" , "b" :"bar"}

what is the simplest way to do this in plain javascript. I am not using any external libraries like jquery or underscore.

check this : https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/assign — Niklesh Raut, Jul 12 '16 at 08:33
Please search SO before asking your question, this has been asked before. — gcampbell, Jul 12 '16 at 08:34

score 3 · Accepted Answer · answered Jul 12 '16 at 08:33

3

Use Object.assign, here is the documentation.

var mergedObject = Object.assign(a, b);

Be aware that Object.assign will merge from left to right so any keys that are the same will be overridden if added later in the parameter list.

answered Jul 12 '16 at 08:33

Davin Tryon

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This will change `a`. – str Jul 12 '16 at 08:36
`Object.assign({}, a, b)` is how you should do it if you don't want to mutate your original objects. – Joe Clay Jul 12 '16 at 08:40

score 2 · Answer 2 · answered Jul 12 '16 at 08:35

2

var o1 = {"aa" : "foo" };
var o2 = { "b" : "bar" };

var obj = Object.assign(o1, o2);

answered Jul 12 '16 at 08:35

Gayathri Mohan

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score 2 · Answer 3 · edited Jul 12 '16 at 09:40

Ideally, as suggested in the previous two answers, using Object.assign is your best bet, unless browser support dictates otherwise, although, the MDN documentation provides an ES5 polyfill.

if (typeof Object.assign != 'function') {
  Object.assign = function(target) {
    'use strict';
    if (target == null) {
      throw new TypeError('Cannot convert undefined or null to object');
    }

    target = Object(target);
    for (var index = 1; index < arguments.length; index++) {
      var source = arguments[index];
      if (source != null) {
        for (var key in source) {
          if (Object.prototype.hasOwnProperty.call(source, key)) {
            target[key] = source[key];
          }
        }
      }
    }
    return target;
  };
}

his tag is only javascript no Jquery – Gayathri Mohan Jul 12 '16 at 08:36 — Gayathri Mohan, Jul 12 '16 at 08:36
You can check the updated Javascript solution @gayathri – Ramcharan Reddy Jul 12 '16 at 08:39 — Ramcharan Reddy, Jul 12 '16 at 08:39

How can I Merge two JavaScript objects?

3 Answers3