extend.js

var extend = (function () {
    var own = function (parent, child) {
        return Object.prototype.hasOwnProperty.call(parent, child);
    };

    return function (out) {
        out = out || {};

        for (var i = 1, len = arguments.length; i < len; i++) {
            if (!arguments[i]) {
                continue;
            }

            for (var key in arguments[i]) {
                if (own(arguments[i],key)) {
                    out[key] = arguments[i][key];
                }
            }
        }

        return out;
    };
}());