jquery.objectdiff.js

/**
 * jquery-objectdiff  - a jQuery plugin
 *
 * version 1.0.2
 *
 * This plugin is just a helper function for calculating a diff of two similar
 * objects ala ActiveRecord's changes hash. Just pass in two objects and this
 * function will return an object of changes that contains only the properties
 * that have changed. Differences are stored in arrays; the first element has
 * the 'before' value and the second element is the 'after' value.
 *
 * Usage:
 *
 *    var before = {id:123, name:{first:"Johnny", last:"Johnson"}};
 *    var after = {id:123, name:{first:"John", last:"Johnson"}, age:30};
 *    var changes = $.objectDiff(before, after);
 *
 * Result (contents of changes):
 *
 *    {name: {first:["Johnny","John"]}, age:[null,30]}
 *
 */
(function ($) {
    $.objectDiff = function (a, b, c) {
        c = {};
        $.each([a, b], function (index, obj) {
            for (prop in obj) {
                if (obj.hasOwnProperty(prop)) {
                    if (typeof obj[prop] === "object" && obj[prop] !== null) {
                        c[prop] = $.objectDiff(a[prop], b[prop], c);
                    }
                    else {
                        if(a===undefined) a = {};
                        if(b===undefined) b = {};
                        if (a[prop] !== b[prop]) {
                            c[prop] = [a[prop], b[prop]];
                        }
                    }
                }
            }
        });
        return c;
    }
})(jQuery);