EventBus.ts

class EventBus {
  private handlers: Record<string, ((...args: any[]) => void)[]> = {};

  trigger(eventName: string, ...args: any[]) {
    if (this.handlers[eventName]) {
      this.handlers[eventName].forEach((handler) => handler(...args));
    }
  }

  on(eventName: string, handler: (...args: any[]) => void) {
    if (!this.handlers[eventName]) {
      this.handlers[eventName] = [];
    }

    this.handlers[eventName].push(handler);
  }

  once(eventName: string, handler: (...args: any[]) => void) {
    if (!this.handlers[eventName]) {
      this.handlers[eventName] = [];
    }

    const oneTimeHandler = () => {
      handler.apply(this, arguments);
      this.off(eventName, oneTimeHandler);
    };

    this.handlers[eventName].push(oneTimeHandler);
  }

  off(eventName: string, handler?: (...args: any[]) => void) {
    if (!this.handlers[eventName]) return;

    if (!handler) {
      delete this.handlers[eventName];
    }

    const indexOfHandler = this.handlers[eventName].indexOf(handler);
    if (indexOfHandler !== -1) {
      this.handlers[eventName].splice(indexOfHandler, 1);
    }
  }
}