web_dist/src/utils/mitt.ts

class EventBus<T extends Record<string, (...args: any[]) => any>> {
  emits: Map<keyof T, T[keyof T]> = new Map<keyof T, T[keyof T]>();

  on<K extends keyof T>(name: K, callback: T[K]): void {
    this.emits.set(name, callback);
  }

  off<K extends keyof T>(name: K): void {
    this.emits.delete(name);
  }

  exists<K extends keyof T>(name: K): boolean {
    return this.emits.has(name);
  }

  emit<K extends keyof T>(
    name: K,
    ...args: Parameters<T[K]>
  ): ReturnType<T[K]> | null {
    if (this.emits.has(name)) {
      const cb = this.emits.get(name);
      let result = null;
      try {
        result = cb!(...args);
      } catch (e) {
        console.error(e);
      }
      return result;
    }
    return null;
  }
}

export default EventBus;