Just "invented" these patters today, when i should be working 
in C# you may subscribe to events, adding events like this:
myObject.Click += new EventHandler(myObject_Clicked);
and you may define your own return EventArgs:
//EventArgs Definition
public class StoppedEventArgs : EventArgs
{
public Vector StoppedPosition { get; set; }
}
//Event is being fired
if(Stopped != null)
{
Stopped(this, new StoppedEventArgs { StoppedPosition = pos });
}
//Subscription
Sparcle.Stopped += new EventHandler<StoppedEventArgs>(Sparcle_Stopped);
//EventHandler
void Sparcle_Stopped(object sender, StoppedEventArgs e)
{
Sparcle s = (Sparcle)sender;
double angle = rnd.NextDouble() * 2 * Math.PI;
s.spd.X = Math.Cos(angle) * rnd.NextDouble() * 1;
s.spd.Y = Math.Sin(angle) * rnd.NextDouble() * 1;
}
Now lets transfer these patterns to Javascript:
//Advanced EventArgs
function AdvEventArgs(x,y,z){
this.X = x;
this.Y = y;
this.Z = z;
}
function MyObject(){
//**** SIMPLE EVENT *****************
this.onEvent =
null;
var fireEvent =
function(){
if(
this.onEvent!==
null){
this.onEvent();
}
};
//**** ADVANCED EVENT ***************
this.onAdvEvent =
null;
var fireAdvEvent =
function(){
if(
this.onAdvEvent!==
null){
this.onAdvEvent(
new AdvEventArgs(1,2,3));
}
};
}
var obj =
new MyObject();
//SIMPLE SUBSCRIPTION
function SimpleHandler(){
alert("Simple Event");
}
obj.onEvent = SimpleHandler;
//ADVANCED SUBSCRIPTION
function AdvancedHandler(Args){
alert
(
"X:" + Args.X +
", Y:" + Args.Y +
", Z:" + Args.Z
);
}
obj.onAdvEvent = AdvancedHandler;
So now we have custom events in simple and advanced form, just like we know them from C# 
Now lets make things more exciting... In C# you may subscribe to the same event with multiple handlers, so lets do that in Javascript too:
function MyObject2(){
var EventListeners = [];
this.onEvent = function(Handler)
{
EventListeners.push( Handler );
};
var fireEvent = function()
{
for(var i=0,listener ; (Listener=EventListeners[i]) ; i++)
{
listener();
}
};
}
var obj2 = new MyObject2();
function Handler1(){ alert(1); }
function Handler2(){ alert(2); }
obj2.onEvent( Handler1 );
obj2.onEvent( Handler2 );