Returns the number of registered listeners for the event named eventName.
For EventEmitters this behaves exactly the same as calling .listenerCount
on the emitter.
For EventTargets this is the only way to obtain the listener count. This can
be useful for debugging and diagnostic purposes.
Returns the number of registered listeners for the event named
eventName.For
EventEmitters this behaves exactly the same as calling.listenerCounton the emitter.For
EventTargets this is the only way to obtain the listener count. This can be useful for debugging and diagnostic purposes.