Event Emitter

EventEmitter is extended by FlipClock, which provides event bus on all clocks.

Instantiate

function eventEmitter<T>(): EventEmitter<T>;

Returns

class EventEmitter<T> {
    /**
     * The registered events.
     *
     * @protected
     */
    protected events: Event<T, any>[];
    /**
     * Emit an event.
     *
     * @public
    */
    emit<K extends keyof Required<T>>(key: K, ...args: Required<T>[K] extends (...args: infer P) => void ? P : any[]): void;
    /**
     * Listen for an event. This returns a function to unwatch the event.
     *
     * @public
     */
    on<K extends keyof Required<T>>(key: K, fn: EventEmitterCallback<T, K>): () => void;
    /**
     * Listen for an event once.
     *
     * @public
     */
    once<K extends keyof Required<T>>(key: K, fn: EventEmitterCallback<T, K>): () => void;
    /**
     * Stop listening for all events using a, or with a key and a function.
     *
     * @public
     */
    off<K extends keyof Required<T>>(key: K): void;
    off<K extends keyof Required<T>>(key: K, fn: T[K]): void;
    /**
     * Reset the event bus and remove all watchers.
     *
     * @public
     */
    reset(): void;
}

Usage

const emitter = eventEmitter<{
    foo: () => void
    bar: () => void
}>();

const foo = vi.fn();
const bar = vi.fn();

emitter.on('foo', foo);
emitter.on('bar', bar);
emitter.once('foo', foo);

const unwatch = emitter.on('foo', foo);

emitter.emit('foo');

unwatch();