gistfile1.js

var Foo = (function () {
    var prop;
    
    function Foo(bar) {
        this.prop = bar || "baz";
    }
 
    // private/protected functions here
    function priv() {
        return "Private: " + prop;
    }
 
    
    function pub() {
        return "Public: " + priv();
    }
    
    Foo.prototype = {
        pub : pub
    };
 
    return Foo;
})();

var f = new Foo("bar");

console.log(f.pub());