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EZ Web Audio / TypedEventEmitter

Class: TypedEventEmitter<TMap> ​

Defined in: packages/core/src/events/typed-event-emitter.ts:26

Typed event emitter base class for audio lifecycle events.

Extends the native EventTarget API with:

  • Type-safe addEventListener / removeEventListener overloads
  • A protected emit() helper that creates and dispatches typed CustomEvent instances
  • Chainable on() / once() / off() convenience methods

Usage — extend this class with a concrete event map:

typescript
interface MyEventMap {
  play: CustomEvent<{ time: number }>
  stop: CustomEvent<{ time: number }>
}

class MyEmitter extends TypedEventEmitter<MyEventMap> {
  trigger() {
    this.emit('play', { time: Date.now() })
  }
}

Extends ​

  • EventTarget

Extended by ​

Type Parameters ​

TMap ​

TMap extends { [K in keyof TMap]: CustomEvent<unknown> }

Record mapping event name strings to CustomEvent types.

Constructors ​

Constructor ​

new TypedEventEmitter<TMap>(): TypedEventEmitter

Defined in: node_modules/.pnpm/typescript@5.9.3/node_modules/typescript/lib/lib.dom.d.ts:11586

Returns ​

TypedEventEmitter

Inherited from ​

EventTarget.constructor

Methods ​

_clearListeners() ​

protected _clearListeners(): void

Defined in: packages/core/src/events/typed-event-emitter.ts:192

Remove every listener registered through this emitter (via addEventListener(), on(), or once()), regardless of how many or what event type they're bound to.

Native EventTarget has no removeAllListeners(). This works around that by aborting a shared AbortSignal threaded through every addEventListener() call this class makes, then swapping in a fresh AbortController so the instance can keep accepting new listeners afterward (e.g. if it's reused before being garbage collected).

Subclasses call this from their dispose() alongside neutering dispatchEvent — the neuter stops future emits, this stops stale listener closures from being retained/invoked at all.

Returns ​

void

addEventListener() ​

Call Signature ​

addEventListener<K>(type, listener, options?): void

Defined in: packages/core/src/events/typed-event-emitter.ts:44

Add a typed event listener for known event types. Overloaded to provide type safety for known event types while remaining compatible with the native EventTarget API.

Type Parameters ​
K ​

K extends string

Parameters ​
type ​

K

The event type (key of TMap)

listener ​

(event) => void

Typed event handler

options? ​

Standard addEventListener options

boolean | AddEventListenerOptions

Returns ​

void

Overrides ​

EventTarget.addEventListener

Call Signature ​

addEventListener(type, listener, options?): void

Defined in: packages/core/src/events/typed-event-emitter.ts:49

Add a typed event listener for known event types. Overloaded to provide type safety for known event types while remaining compatible with the native EventTarget API.

Parameters ​
type ​

string

The event type (key of TMap)

listener ​

Typed event handler

EventListenerOrEventListenerObject | null

options? ​

Standard addEventListener options

boolean | AddEventListenerOptions

Returns ​

void

Overrides ​

EventTarget.addEventListener

emit() ​

protected emit<K>(type, detail): void

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

Emit a typed event with the given detail.

Creates a CustomEvent with the provided detail and dispatches it on this target. Subclasses call this internally to fire lifecycle events.

Type Parameters ​

K ​

K extends string

Parameters ​

type ​

K

The event type to emit (key of TMap)

detail ​

TMap[K]["detail"]

The event detail object (typed by TMap)

Returns ​

void

off() ​

off<K>(type, listener): this

Defined in: packages/core/src/events/typed-event-emitter.ts:167

Unsubscribe from an event.

Note: Due to native EventTarget limitations, you must provide the same listener function reference that was used when subscribing.

Type Parameters ​

K ​

K extends string

Parameters ​

type ​

K

The event type to unsubscribe from

listener ​

(event) => void

The event handler function to remove

Returns ​

this

this for chaining

Example ​

typescript
const handler = (e) => console.log(e.detail)
emitter.on('play', handler)
// later...
emitter.off('play', handler)

on() ​

on<K>(type, listener): this

Defined in: packages/core/src/events/typed-event-emitter.ts:116

Subscribe to one or more events. Supports chaining.

Type Parameters ​

K ​

K extends string

Parameters ​

type ​

The event type(s) to subscribe to (key or array of keys of TMap)

K | K[]

listener ​

(event) => void

The event handler function

Returns ​

this

this for chaining

Example ​

typescript
emitter.on('play', handlePlay).on('stop', handleStop)
emitter.on(['play', 'stop'], handleBoth)

once() ​

once<K>(type, listener): this

Defined in: packages/core/src/events/typed-event-emitter.ts:141

Subscribe to an event once. Handler is removed after first invocation.

Type Parameters ​

K ​

K extends string

Parameters ​

type ​

K

The event type to subscribe to

listener ​

(event) => void

The event handler function

Returns ​

this

this for chaining

Example ​

typescript
emitter.once('end', () => console.log('Finished'))

removeEventListener() ​

Call Signature ​

removeEventListener<K>(type, listener, options?): void

Defined in: packages/core/src/events/typed-event-emitter.ts:70

Remove a typed event listener for known event types. Overloaded to provide type safety for known event types while remaining compatible with the native EventTarget API.

Type Parameters ​
K ​

K extends string

Parameters ​
type ​

K

The event type (key of TMap)

listener ​

(event) => void

Typed event handler to remove

options? ​

Standard removeEventListener options

boolean | EventListenerOptions

Returns ​

void

Overrides ​

EventTarget.removeEventListener

Call Signature ​

removeEventListener(type, listener, options?): void

Defined in: packages/core/src/events/typed-event-emitter.ts:75

Remove a typed event listener for known event types. Overloaded to provide type safety for known event types while remaining compatible with the native EventTarget API.

Parameters ​
type ​

string

The event type (key of TMap)

listener ​

Typed event handler to remove

EventListenerOrEventListenerObject | null

options? ​

Standard removeEventListener options

boolean | EventListenerOptions

Returns ​

void

Overrides ​

EventTarget.removeEventListener