Cloning an Object (v123)

Revision 123 of this benchmark created by tim.roststock on

Description

There is no quick and easy facility for cloning an object, Some people recommend using JQuery.extend others JSON.parse/stringify

http://stackoverflow.com/questions/122102/what-is-the-most-efficient-way-to-clone-a-javascript-object

If you want the fastest possible clone function. I would personally anticipate the data structure of your object and write a custom clone to handle it.

In the current moment, the fastest way to clone an object is using the Cached Douglas Crockfords Object.create clone function.

Preparation HTML

<script src="http://code.jquery.com/jquery-2.0.3.js" type="text/javascript"></script>


<script>
  var oldObject = {
   a: 1,
   b: 2,
   c: 3,
   d: 4,
   e: 5,
   f: 6,
   g: 7
  };
  
  
  function clone(obj) {
   var target = {};
   for (var i in obj) {
    if (obj.hasOwnProperty(i)) {
     target[i] = obj[i];
    }
   }
   return target;
  }
  
  Object.defineProperties(Object, {
   'extend': {
    'configurable': true,
    'enumerable': false,
    'value': function extend(what, wit) {
     var extObj, witKeys = Object.keys(wit);
  
     extObj = Object.keys(what).length ? Object.clone(what) : {};
  
     witKeys.forEach(function(key) {
      Object.defineProperty(extObj, key, Object.getOwnPropertyDescriptor(wit, key));
     });
  
     return extObj;
    },
    'writable': true
   },
   'clone': {
    'configurable': true,
    'enumerable': false,
    'value': function clone(obj) {
     return Object.extend({}, obj);
    },
    'writable': true
   }
  });

//Crockford clone function
function object(o) {
    function F() {}
    F.prototype = o;
    return new F();
}

//Crockford cashed clone function

if (typeof Object.create !== "function") {
  Object.create = (function () {
    function FC() {} // created only once
    return function (o) {
      FC.prototype = o; // reused on each invocation
      return new FC();
    };
  })();
}


// Nodejs util _extend
function nodeextend (origin, add) {
  // Don't do anything if add isn't an object
  if (!add || typeof add !== 'object') return origin;

  var keys = Object.keys(add);
  var i = keys.length;
  while (i--) {
    origin[keys[i]] = add[keys[i]];
  }
  return origin;
};


function recursive(obj){
    if(obj == null || typeof(obj) != 'object')
        return obj;

    var temp = obj.constructor(); // changed

    for(var key in obj)
        temp[key] = recursive(obj[key]);
    return temp;
}
</script>

Test runner

Ready to run.

Testing in
TestOps/sec
JQuery.extend deep
var newObject = jQuery.extend(true, {}, oldObject);
ready
JSON
var newObject = JSON.parse(JSON.stringify(oldObject));
ready
JQuery.extend
var newObject = jQuery.extend({}, oldObject);
ready
simple clone function
var newObject = clone(oldObject);
ready
ES5 Object.clone
var newObject = Object.clone(oldObject);
ready
Crockford Clone Function
var newObject = object(oldObject);
ready
Crockford Cashed Clone
var newObject = Object.create(oldObject);
ready
Nodejs require('util')._extend
var newObject = nodeextend({}, oldObject);
ready
recursive
var newObject = recursive(oldObject);
ready
Simple for..in Function
    var newObject = {};
    for (var k in oldObject) {
      newObject[k] = oldObject[k];
    }
ready
known props
var newObject = {
  a: oldObject.a,
  b: oldObject.b,
  c: oldObject.c,
  d: oldObject.d,
  e: oldObject.e,
  f: oldObject.f,
  g: oldObject.g
};
ready

Revisions

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