http://stackoverflow.com/questions/171251/how-can-i-merge-properties-of-two-javascript-objects-dynamically

merge-arrays.js

for (var attrname in obj2) { obj1[attrname] = obj2[attrname]; }

// smashless version
/**
 * Overwrites obj1's values with obj2's and adds obj2's if non existent in obj1
 * @param obj1
 * @param obj2
 * @returns obj3 a new object based on obj1 and obj2
 */
function merge_options(obj1,obj2){
    var obj3 = {};
    for (var attrname in obj1) { obj3[attrname] = obj1[attrname]; }
    for (var attrname in obj2) { obj3[attrname] = obj2[attrname]; }
    return obj3;
}


// jQuery?

// merge options object into settings object
var settings = { validate: false, limit: 5, name: "foo" };
var options  = { validate: true, name: "bar" };
jQuery.extend(settings, options);
// now the content of settings object is the following:
// { validate: true, limit: 5, name: "bar" }


// smashless
var defaults = { validate: false, limit: 5, name: "foo" };
var options = { validate: true, name: "bar" };

/* merge defaults and options, without modifying defaults */
var settings = $.extend({}, defaults, options);
// the content of settings variable is now the following:
// {validate: true, limit: 5, name: "bar"}
// defaults and options variable remained the same