Function on

on<TPayload = unknown>(
eventName: string,
handler: (event: ExternalHookPayload<TPayload>) => void,
): void
Register a handler to be invoked when a given event happens
Type Parameters
- TPayload = unknown
Parameters
- eventName: string
  The name of the event to subscribe
- handler: (event: ExternalHookPayload<TPayload>) => void
  Function called with the event payload
Returns void