SImple extend

extend.js

var extend = function(target, source) {
    target = target || {};
    
    for (var prop in source) {
        if (!source.hasOwnProperty(prop)) continue;

        if (typeof source[prop] === 'object') {
            target[prop] = extend(target[prop], source[prop]);
        } else {
            target[prop] = source[prop];
        }
    }

    return target;
};