EventEmitter

Defined in: packages/core/src/utils/event-emitter.ts:45

Type-safe event emitter with strongly-typed event names and payloads

Remarks

This class provides a type-safe event emitter pattern where event names and their payload types are strictly enforced. It’s designed to be extended by classes that need event emission capabilities.

Example

interface MyEvents {
  connect: void;
  message: { text: string };
  error: { error: Error };
}

class MyEmitter extends EventEmitter<MyEvents> {
  connect() {
    this.emit('connect', undefined);
  }

  sendMessage(text: string) {
    this.emit('message', { text });
  }
}

const emitter = new MyEmitter();
emitter.on('message', (data) => {
  console.log(data.text); // Strongly typed!
});

Extended by

• BaseConnection
• LoadingManager

Type Parameters

Type Parameter	Description
Events extends Record<string, unknown>	Record of event names to payload types

Constructors

Constructor

new EventEmitter<Events>(): EventEmitter<Events>

Returns

EventEmitter<Events>

Methods

eventNames()

eventNames(): keyof Events[]

Defined in: packages/core/src/utils/event-emitter.ts:211

Get all event names that have registered handlers

Returns

keyof Events[]

Array of event names

Example

const events = emitter.eventNames();
console.log('Events with handlers:', events);

---

hasListeners()

hasListeners<K>(event): boolean

Defined in: packages/core/src/utils/event-emitter.ts:228

Check if an event has any registered handlers

Type Parameters

Type Parameter
K extends string | number | symbol

Parameters

Parameter	Type	Description
event	K	Event name

Returns

boolean

True if the event has at least one handler

Example

if (emitter.hasListeners('message')) {
  emitter.emit('message', { text: 'Hello' });
}

---

listenerCount()

listenerCount<K>(event): number

Defined in: packages/core/src/utils/event-emitter.ts:195

Get the number of handlers registered for an event

Type Parameters

Type Parameter
K extends string | number | symbol

Parameters

Parameter	Type	Description
event	K	Event name

Returns

number

Number of registered handlers

Example

const count = emitter.listenerCount('message');
console.log(`${count} handlers registered`);

---

off()

off<K>(event, handler): void

Defined in: packages/core/src/utils/event-emitter.ts:120

Remove an event handler

Type Parameters

Type Parameter
K extends string | number | symbol

Parameters

Parameter	Type	Description
event	K	Event name
handler	EventHandler<Events[K]>	Handler function to remove

Returns

void

Example

const handler = (data) => console.log(data);
emitter.on('message', handler);
emitter.off('message', handler);

---

on()

on<K>(event, handler): () => void

Defined in: packages/core/src/utils/event-emitter.ts:65

Register an event handler

Type Parameters

Type Parameter
K extends string | number | symbol

Parameters

Parameter	Type	Description
event	K	Event name to listen for
handler	EventHandler<Events[K]>	Callback function to invoke when event is emitted

Returns

Unsubscribe function that removes this specific handler

() => void

Example

const unsubscribe = emitter.on('message', (data) => {
  console.log(data.text);
});

// Later, to unsubscribe:
unsubscribe();

---

once()

once<K>(event, handler): void

Defined in: packages/core/src/utils/event-emitter.ts:95

Register a one-time event handler

Type Parameters

Type Parameter
K extends string | number | symbol

Parameters

Parameter	Type	Description
event	K	Event name to listen for
handler	EventHandler<Events[K]>	Callback function to invoke once

Returns

void

Remarks

The handler will be automatically removed after being invoked once.

Example

emitter.once('connect', () => {
  console.log('Connected!');
});

---

removeAllListeners()

removeAllListeners<K>(event?): void

Defined in: packages/core/src/utils/event-emitter.ts:175

Remove all handlers for an event, or all handlers for all events

Type Parameters

Type Parameter
K extends string | number | symbol

Parameters

Parameter	Type	Description
event?	K	Optional event name. If omitted, removes all handlers for all events.

Returns

void

Example

// Remove all handlers for 'message' event
emitter.removeAllListeners('message');

// Remove all handlers for all events
emitter.removeAllListeners();