How to execute a function at the end of the animation?

Question

JavaScript

Hello! Tell me please. I have some class that inherits from Fx:

var cl = new Class({
   Extends: Fx,
   initialize: function (elem) {
      this.elem = elem;
   },
   set: function (now) {
      this.setStyle('opacity', now);
   }
});

And I need to perform some function at the end of the animation. How to implement? :)

Answer 1

initialize: function (elem) {
    //...
    this.addEvent('complete', function(){ ... });
},

Answer 2

By the way, elements already have a fade method, no new class needed:
mootools.net/docs/core/Fx/Fx.Tween#Element :fade