Cloning an Object (v60)

Revision 60 of this benchmark created by Stefano Sergio 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: 4,
    e: 5,
    g: {
      a: [7, 8, 9, 54.6435, 354, 353, 453.4, 534, 53.4, 5.34, 52.4, 234, 6, 678, 76.84, 53, 73, 54.2, 57, 45, 3, 67, 78, 7265, 7, 546, 37, 8, 6, 8, 436.4, 64.3, 6, 8, 7, 6, 74.7, 3634.636, 43.6, 567.8735, 3675, 7346, 834, 737643, 6, 7436, 57, 47, 57.46, 57, 46, 74.6, 7, 56.7, 26.3, 67.7, 5474.5745, 754, 754, 745, 7],
      b: [354, 35, 1, 312, 32.4, 35, 7, 76878.8, 686.7, 78.98, 77, 46.3, 3452, 13, 435, 4, 86.7, 987.89, 86775.6, 4565, 88.9, 9, 6, 75678, 9, 9067, 46, 356.65, 8.95, 246.5, 87, 678, 465.6, 86.8, 63, 56, 867.86, 43, 65.67, 586.85, 734, 77, 867, 43, 6, 67, 67.864757, 86, 8, 3.62, 5, 6, 767, 9878.85, 4.6, 867, 7436, 7, 4, 721, 5, 765, 8, 6, 3245, 7548, 53.67, 437.6],
      c: [7, 8, 9, 54.6435, 354, 353, 453.4, 534, 53.4, 5.34, 52.4, 234, 6, 678, 76.84, 53, 73, 54.2, 57, 45, 3, 67, 78, 726.5, 7, 54.6, 37, 8, 6, 8, 436.4, 64.3, 6, 8, 7, 6, 74.7, 3634.636, 43.6, 567.86735, 3675, 734.6, 834, 737.643, 6, 74.36, 57, 47, 57.46, 57, 46, 74.6, 7, 56.7, 26.3, 67.7, 5474.5745, 754, 754, 74.5, 7]
    }
  };


  var object_create = Object.create;
  if (typeof object_create !== 'function') {
    object_create = function(o) {
      function F() {}
      F.prototype = o;
      return new F();
    };
  }

  function deepCopy(src) {
    if (src === null || typeof(src) !== 'object') {
      return src;
    }

    //Honor native/custom clone methods
    if (typeof src.clone === 'function') {
      return src.clone(true);
    }

    //Special cases:
    //Date
    if (src instanceof Date) {
      return new Date(src.getTime());
    }
    //RegExp
    if (src instanceof RegExp) {
      return new RegExp(src);
    }
    //DOM Elements
    if (src.nodeType && typeof src.cloneNode === 'function') {
      return src.cloneNode(deep);
    }

    var proto = (Object.getPrototypeOf ? Object.getPrototypeOf(src) : src.__proto__);
    if (!proto) {
      proto = src.constructor.prototype;
    }
    var ret = object_create(proto);

    for (var key in src) {
      ret[key] = deepCopy(src[key]);
    }
    return ret;
  }
</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
Native For..in
var newObject = clone(oldObject);
function clone(old) {
        var obj = {};
        for (var i in old) {
          if (old.hasOwnProperty(i)) {
            obj[i] = old[i];
          }
        }
        return obj;
}
ready

Revisions

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