Cloning an Object (v79)

Revision 79 of this benchmark created by Marcin 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.

Preparation HTML

<script src="http://code.jquery.com/jquery-1.5.1.js" type="text/javascript"></script>


<script>
/*
   Description: Performs JSON-safe deep cloning. Equivalent of JSON.parse(JSON.stringify()).
   Based on deepClone7() by Kyle Simpson (https://github.com/getify)
   Source: http://jsperf.com/deep-cloning-of-objects,
   http://jsperf.com/structured-clone-objects/2
   https://developer.mozilla.org/en-US/docs/Web/Guide/DOM/The_structured_clone_algorithm
   */

  function deepCopy(objToBeCopied) {
    if (objToBeCopied === null || !(objToBeCopied instanceof Object)) {
      return objToBeCopied;
    }
    var copiedObj, fConstr = objToBeCopied.constructor;
    copiedObj = new fConstr();
    for (var sProp in objToBeCopied) {
      if (objToBeCopied.hasOwnProperty(sProp)) {
        copiedObj[sProp] = deepCopy(objToBeCopied[sProp]);
      }
    }
    return copiedObj;
  }

  var oldObject = {
   a: 1,
   b: 2,
   c: 3,
   d: 4,
   e: 5,
   f: {foo: "Bar", baz: "BART"},
   g: [7, 8, 9]
  };
  
  
  function clone(obj) {
   var target = {};
   for (var i in obj) {
    if (obj.hasOwnProperty(i)) {
     target[i] = obj[i];
    }
   }
   return target;
  }
  function clone2 (obj) {
    return Object.keys(obj).reduce(function(c,k){c[k]=obj[k];return c;},{})
  }
  
  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
   }
  });
</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
clone2
var newObject = clone2(oldObject);
ready
deepCopy
var newObject = deepCopy(oldObject);
ready

Revisions

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