function Person(name, surname) {
	this.name = name;
	this.surname = surname;

}

Object.defineProperty(
            Person.prototype, 
            "fullName", {
              get: function() { return this.name + " " + this.surname; }
            });

Object.defineProperty(
            Developer.prototype, 
            "fullName", {
              get: function() { return "Dew. " + this.name + " " + this.surname; }
            });


var johnSmith = new Person("Jan", "Kowalski");
var marioRossi = new Developer("Mario", "Rossi", "JavaScript");

console.log(johnSmith.fullName);		// wynik: "Jan Kowalski"
console.log(marioRossi.fullName);		// wynik: "Dew. Mario Rossi"