C# like events in Javascript

C# like events in Javascript

How can I create a new event/ like in c# in javascript?
private event EventHandler asdCompleted;
private void SetEventHandlers()
{
this.asdCompleted += asd_completed;
}
private void asd_completed(object sender, EventArgs e)
{
}
and fire the event anywhere like in c#:
this.asdCompleted(this, null);