var Greeter = function(who){
  this.toGreet = who;
   this.sayHello = function(){
    alert("Hello, " + this.toGreet + "!");
  }
};

var extendedGreeter = function() {
  this.bavarianHello = function(){
    alert("Pfiat' Di," + this.toGreet + "!");
  }
};
extendedGreeter.prototype = new Greeter("Vroni");
greeter3 = new extendedGreeter('Vroni');
greeter3.sayHello(); //-> Hello, Vroni!
greeter3.bavarianHello(); //-> Pfiat' Di, Vroni!