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listenerCount() ​

Returns the number of listeners registered for a given event, or the total number of listeners across all events when called without an argument.

Example ​

typescript
const count = instance.listenerCount("foo");
// count: 2

const total = instance.listenerCount();
// total: 5

Parameters ​

ParameterTypeDescription
eventstring | symbol(Optional) The event name. Expects an ESMitterEventName. When omitted, the total listener count across all events is returned.

Returns ​

TypeDescription
numberThe number of listeners registered for the event, or the total across all events if no argument is given.

Notes ​

  • If no listeners are registered for the event, 0 is returned.
  • When called without an argument, 0 is returned if no listeners are registered for any event.