var merge = function(target, source) {
        for(var attr in source) {
           if(typeof(target[attr]) === "object" && typeof(source[attr]) === "object")
             {
                merge(target[attr], source[attr]);
            } else {
                target[attr] = source[attr];
            }
        }
        return target;
    };
    

[ hint: ever heard of __proto__ ]