cloning an object (v26)

Revision 26 of this benchmark created by Ferdinand Prantl 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="//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>

Setup

var oldObject = {
       a: 1,
       b: 2,
       c: 3,
       d: 4,
       e: 5,
       f: function() {
        return 6;
       },
       g: [7, 8, 9],
       h: {
         a: 1,
         b: 2,
         c: 3
       }
      };
      
      function replicate (obj) {
        return {
        a: obj.a,
        b: obj.b,
        c: obj.c,
        d: obj.d,
        e: obj.e,
        f: obj.f,
        g: obj.g,
        h: obj.h
       };
      }
      
      function clone_keys(obj) {
       var target = {};
       var keys = Object.keys(obj)
       for(var i = 0; i < keys.length; i++) {
          var key = keys[i]
          if (obj.hasOwnProperty(key)) {
             target[key] = obj[key]
          }
       }
       return target;
      }
    
      function clone(obj) {
       var target = {};
       for (var i in obj) {
        if (obj.hasOwnProperty(i)) {
         target[i] = obj[i];
        }
       }
       return target;
      }
      
      function deepClone(obj) {
       if (obj == null || typeof obj !== 'object') {
         return obj;
       }
       var target = obj.constructor();
       for (var key in obj) {
        if (obj.hasOwnProperty(key)) {
         target[key] = deepClone(obj[key]);
        }
       }
       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
       }
      });

Test runner

Ready to run.

Testing in
TestOps/sec
jQuery.extend() deep
var newObject = jQuery.extend(true, {}, oldObject);
ready
JSON stringify/parse
var newObject = JSON.parse(JSON.stringify(oldObject));
ready
jQuery.extend()
var newObject = jQuery.extend({}, oldObject);
ready
clone with Object.keys() function
var newObject = clone_keys(oldObject);
ready
ES5 Object.clone
var newObject = Object.clone(oldObject);
ready
stringify eval
var newObject = eval("("+JSON.stringify(oldObject)+")");
ready
replicate function
// Copies known, static object structure. Manual cloning
var newObject = replicate(oldObject);
ready
clone function
var newObject = clone(oldObject);
ready
deepClone function
var newObject = deepClone(oldObject);
ready

Revisions

You can edit these tests or add more tests to this page by appending /edit to the URL.