cloning an object

JavaScript performance comparison

Revision 16 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="//cdnjs.cloudflare.com/ajax/libs/lodash.js/2.4.1/lodash.min.js"></script>
<script>
Benchmark.prototype.setup = function() {
    var oldObject = {
                a: 1,
                b: 2,
                c: 3,
                d: 4,
                e: 5,
                f: function() {
                        'use strict';
                        return 6;
                },
                g: [7, 8, 9]
        },
   
        oldArray = [
                1, 2, 3, 4, 5,
                function() {
                        'use strict';
                        return 6;
                },
                [7, 8, 9]
        ];
   
        clone = function(source) {
                'use strict';
                var copy, i;
                if (Object.prototype.toString.call(source) === '[object Array]') {
                        copy = [];
                        for (i=0; i<source.length; i++) {
                                copy[i] = clone(source[i]);
                        }
                        return copy;
                } else if (typeof(source) === 'object') {
                        copy = {};
                        for (var prop in source) {
                                if (source.hasOwnProperty(prop)) {
                                        copy[prop] = clone(source[prop]);
                                }
                        }
                        return copy;
                } else {
                        return source;
                }
        };
};
</script>

Preparation code output

Test runner

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Testing in unknown unknown
Test Ops/sec
clone(obj)
var newObject = clone(oldObject);
pending…
$.extend(obj) deep
var newObject = jQuery.extend(true, {}, oldObject);
pending…
loDash(obj) deep
var newObject = _.clone(oldObject, true);
pending…

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