function Menu() {

    }

    Menu.prototype = new Menu();
    Menu.prototype.constructor = Menu;
    Menu.prototype = (function(){
        this.visibility = true;
  
        var private_isMenuVisible = function(){
            return this.visibility;
        }

        return {
            constructor: Menu,
            isMenuVisible: function(){
                private_isMenuVisible();
            },
        };

    })();

    var menu = new Menu();
    console.log(menu.isMenuVisible());

isMenuVisible: function(){
                return private_isMenuVisible();
            },