cloning an object (v25)

Revision 25 of this benchmark created 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]
      };
      
      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
       };
      }
      
      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;
      }
      
      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

Revisions

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