Cloning an Object (v65)

Revision 65 of this benchmark created by Jeremy Banks 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>
  var oldObject = {
   a: 1,
   b: 2,
   c: 3,
   d: new Date,
   e: 5,
   f: 9,
   g: [7, 8, 9]
  };
  
  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
   }
  });

function structuredClone(obj) {
    var oldState = history.state;
    history.replaceState(obj);
    var clonedObj = history.state;
    history.replaceState(oldState);
    return clonedObj;
}

var pendingCallbacks = {};

window.addEventListener('message', function(e) {
    var cloneId = e.data.cloneId,
        clonedValue = e.data.value;

    if (e.source === window && cloneId && cloneId in pendingCallbacks) {
        var callback = pendingCallbacks[cloneId];
        delete pendingCallbacks[cloneId];
        callback(clonedValue);
    }
});

var asyncStructuredClone = function(o, callback) {
    var cloneId = String(Math.random());
    pendingCallbacks[cloneId] = callback;
    window.postMessage({ value: o, cloneId: cloneId }, '*');
};
</script>

Test runner

Ready to run.

Testing in
TestOps/sec
JQuery.extend deep
var newObject = jQuery.extend(true, {}, oldObject);
ready
JSON
 
ready
JQuery.extend
 
ready
simple clone function
 
ready
ES5 Object.clone
 
ready
structured clone (using history)
var newObject = structuredClone(oldObject);
ready
async structured clone (using postMessage)
// async test
asyncStructuredClone(oldObject, deferred.resolve);
 
ready

Revisions

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