Typed Event Emitter

event.ts

import { EventEmitter } from "events";

interface TypedEventEmitter<T> {
  addListener<K extends keyof T>(event: K, listener: (arg: T[K]) => void): this;
  on<K extends keyof T>(event: K, listener: (arg: T[K]) => void): this;
  once<K extends keyof T>(event: K, listener: (arg: T[K]) => void): this;
  removeListener<K extends keyof T>(
    event: K,
    listener: (arg: T[K]) => void
  ): this;
  removeAllListeners<K extends keyof T>(event?: K): this;
  emit<K extends keyof T>(event: K, arg: T[K]): boolean;
}


export interface FooEvent {
  arg1: string,
  arg2: number,
}

export interface BarEvent {
  arg1: string,
  arg2: string,
}

interface MyEvents {
  foo: FooEvent;
  bar: BarEvent;
}

class MyEventEmitter extends EventEmitter
  implements TypedEventEmitter<MyEvents> {}