How to clone js object?

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What is the most efficient way to clone a JavaScript object?

How to clone js object with out reference like these:

{ ID: _docEl,
  Index: next,
  DocName: _el
}

Any ideas?

score 11 · Accepted Answer · edited May 23 '17 at 12:08

11

You'll have to iterate over the object and make copies of all its properties.

And then if any of its properties are also objects, assuming you want to clone those too, you'll have to recurse into them.

There's various methods for doing this here: What is the most efficient way to clone a JavaScript object?

edited May 23 '17 at 12:08

Community

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1

answered Aug 13 '10 at 07:21

thomasrutter

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Note too that this isn't one-size-fits-all - this is unlikely to do anything useful for built-in objects like DOM nodes where you'd want to use cloneNode() method, etc. – thomasrutter Aug 13 '10 at 07:35

score 6 · Answer 2 · edited May 23 '17 at 12:01

6

Here's how I'd do it, based on thomasrutter's suggestion (untested code):

function cloneObj(obj) {
    var clone = {};

    for (var i in obj) {
        if (obj[i] && typeof obj[i] == 'object') {
            clone[i] = cloneObj(obj[i]);
        } else {
            clone[i] = obj[i];
        }
    }

    return clone;
}

edited May 23 '17 at 12:01

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answered Aug 13 '10 at 07:22

BoltClock

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`obj.i` will not work, you will access to the `"i"` property literally, you need to use the bracket notation, e.g. `obj[i]` – Christian C. Salvadó Aug 13 '10 at 07:29
1

@CMS: thanks, I've fixed it now. – BoltClock Aug 13 '10 at 07:45
This does not seem right. cloneObject({ name: null }) => {"name":{}} – Niyaz Feb 27 '13 at 14:39
@Niyaz: Thanks, I added a fix. – BoltClock Feb 27 '13 at 14:47

score 5 · Answer 3 · edited May 23 '17 at 12:01

5

You can use jQuery.extend:

// Shallow copy
var newObject = jQuery.extend({}, oldObject);

// Deep copy
var newObject = jQuery.extend(true, {}, oldObject);

The following post is so helpful:

What is the most efficient way to deep clone an object in JavaScript?

edited May 23 '17 at 12:01

Community

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answered Aug 03 '12 at 12:35

Mahmood Dehghan

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the-teacher · Answer 4 · 2012-06-25T10:26:04.253

JavaScript JS object clone

Object._clone = function(obj) {
  var clone, property, value;
  if (!obj || typeof obj !== 'object') {
    return obj;
  }
  clone = typeof obj.pop === 'function' ? [] : {};
  clone.__proto__ = obj.__proto__;
  for (property in obj) {
    if (obj.hasOwnProperty(property)) {
      value = obj.property;
      if (value && typeof value === 'object') {
        clone[property] = Object._clone(value);
      } else {
        clone[property] = obj[property];
      }
    }
  }
  return clone;
};

CoffeeScript JS object clone

# Object clone
Object._clone = (obj) ->
  return obj if not obj or typeof(obj) isnt 'object'
  clone = if typeof(obj.pop) is 'function' then [] else {}

  # deprecated, but need for instanceof method
  clone.__proto__ = obj.__proto__

  for property of obj
    if obj.hasOwnProperty property
      # clone properties
      value = obj.property
      if value and typeof(value) is 'object'
        clone[property] = Object._clone(value)
      else
        clone[property] = obj[property]

  clone

Now you can try to do that

A = new TestKlass
B = Object._clone(A)
B instanceof TestKlass => true

score 1 · Answer 5 · answered Aug 13 '10 at 07:21

1

function objToClone(obj){
  return (new Function("return " + obj))
}

answered Aug 13 '10 at 07:21

Floyd

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Ew, eval()! Not sure this would work either, unless obj has a meaningful toString() method. – thomasrutter Aug 13 '10 at 07:22
would that not return a reference? – borrel Jul 31 '13 at 13:21

How to clone js object?

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