Example Pub-Sub class typescript

Pub-sub.ts

type TEvent = 'player-icu';
type EventCallback<T> = (data: T) => void;

class EventPublisher {
  // Subscription Record<EventName, Record<SubscriberId, callback>>
  private subscriptions: Record<
    string,
    Record<string, EventCallback<unknown>>
  > = {};

  public subscribe<T>(
    subscriberId: string,
    event: TEvent,
    callback: EventCallback<T>
  ): () => void {
    if (!this.subscriptions[event]) {
      this.subscriptions[event] = {};
    }

    this.subscriptions[event][subscriberId] = callback;

    // Returning unsubscribe
    return () => {
      if (this.subscriptions[event]?.[subscriberId]) {
        delete this.subscriptions[event][subscriberId];

        if (Object.values(this.subscriptions[event]).length === 0) {
          delete this.subscriptions[event];
        }
      }
    };
  }

  public echo<T>(event: TEvent, data: T): void {
    if (!this.subscriptions[event]) return;

    for (const subscriptionId in this.subscriptions[event]) {
      const callback = this.subscriptions[event][subscriptionId];
      if (callback) {
        callback(data);
      }
    }
  }
}
export { EventPublisher };