JavaScript | Prototypes

http://www.peterkropff.de/site/javascript/prototypen.htm
http://www.w3schools.com/js/js_object_prototypes.asp
http://www.documentroot.net/allgemein/js-tutorial-klassen-prototypen-oop

or the short way:

# function A() { this.x = 5; }
# function B() { this.y = 6; }
# B.prototype = new A();
# var b = new B();
# alert(b.x); // => 5

(huge thanx to Manuel Bleichner)