cloning an object (v19)

Revision 19 of this benchmark created by Oriol.tf 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.

  1. For this test I just want to compare cloning objects: it is unfair to compare speed between cloning objects and arrays.
  2. I discarded the JSON stringify/parse method because it can't handle functions in objects.

  3. I discarded the protoClone function method because it abuses the function prototype and the returned object is named F:

    // oldObject logs: Object {a: 1, b: 2, c: 3, d: 4, e: 5…}
    // newObject logs: F {a: 1, b: 2, c: 3, d: 4, e: 5…}

  4. I discarded the Object.create(oldObject) method because nested objects/arrays are passed as reference to the newArray.

Preparation HTML

<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>

Setup

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;
                }
        };

Test runner

Ready to run.

Testing in
TestOps/sec
clone(obj)
var newObject = clone(oldObject);
ready
$.extend(obj) deep
var newObject = jQuery.extend(true, {}, oldObject);
ready
loDash(obj) deep
var newObject = _.clone(oldObject, true);
ready

Revisions

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