Javascript - defining and using custom events

This site has a good article that explains the creation and firing of custom javascript events without the use of 3rd party libraries.

Class

var CustomEvent = function() {
 //name of the event
 this.eventName = arguments[0];
 var mEventName = this.eventName;

 //function to call on event fire
 var eventAction = null;

 //subscribe a function to the event
 this.subscribe = function(fn) {
  eventAction = fn;
 };

 //fire the event
 this.fire = function(sender, eventArgs) {
  this.eventName = eventName2;
  if(eventAction != null) {
   eventAction(sender, eventArgs);
  }
  else {
   alert('There was no function subscribed to the ' + mEventName + ' event!');
  }
 };

Register event handlervar myEvent = new CustomEvent("my event");
myEvent.subscribe(function(sender, eventArgs) {
 alert(eventArgs.message);
});

Fire custom event
myEvent.fire(null, {
 message: 'you just witnessed the firing of a custom event called ' + this.eventName + '!'
});