eventNames() 
Returns an array listing the event names for which the emitter has registered listeners.
Example 
typescript
const events = instance.eventNames();
// events: ["foo", "bar"]Returns 
| Type | Description | 
|---|---|
| Array<string | symbol> | An array of event names (strings or symbols) with registered listeners. | 
Notes 
- If no listeners are registered, an empty array is returned.