cloning an object

JavaScript performance comparison

Revision 11 of this test case created

Info

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 code

<script src="//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.0/angular.min.js"></script>
<script>
Benchmark.prototype.setup = function() {
    var oldObject = {
       a: 1,
       b: 2,
       c: 3,
       d: 4,
       e: 5,
       f: function() {
        return 6;
       },
       g: [7, 8, 9]
      };
     
     
      function clone(obj) {
     if(typeof obj === 'object') {
        var copy = {};
        for (var key in obj) {
          if (obj.hasOwnProperty(key)) {
            copy[key] = clone(obj[key]);
          }
        }
        return copy;
      }
      return obj;
      }
     
      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>

Preparation code output

Test runner

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Testing in unknown unknown
Test Ops/sec
jQuery.extend() deep
var newObject = jQuery.extend(true, {}, oldObject);
pending…
JSON stringify/parse
var newObject = JSON.parse(JSON.stringify(oldObject));
pending…
jQuery.extend()
var newObject = jQuery.extend({}, oldObject);
pending…
clone function
var newObject = clone(oldObject);
pending…
ES5 Object.clone
var newObject = Object.clone(oldObject);
pending…
stringify eval
var newObject = eval("("+JSON.stringify(oldObject)+")");
pending…
Angular copy
var newObject =  angular.copy(oldObject);
pending…

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