Returns the number of listeners listening for the event named eventName. If listener is provided, it will return how many times the listener is found in the list of the listeners of the event.
eventName
listener
The name of the event being listened for
Optional
The event handler function
v3.2.0
Returns the number of listeners listening for the event named
eventName. Iflisteneris provided, it will return how many times the listener is found in the list of the listeners of the event.