function Foo(){};

Foo.prototype = function() {

    function private() {};
    function public() {};
    function protected() { };

    return {
        public : public,
        protected : function () {
            if (!(this instanceof Foo)) {
                protected();
            } else {
                throw new ReferenceError("protected is not defined");
            }
        }
    };
}();

function Bar(){};
Bar.prototype = function() {
    var p = Foo.prototype;

    p.protected();

    p.test = function() {
        p.public();
    }

    return p;
}();

var b = new Bar();
b.test();
b.protected();