class EventEmitter {
    constructor() {
        this.handlers = {}
    }

    emit(event) {
        this.handlers[event]?.forEach(h => h());
    }

    addHandler(event, handler) {
        if(!this.handlers[event]) {
            this.handlers[event] = [handler];
        } else {
            this.handlers[event].push(handler);
        }
    }
}

const emitter = new EventEmitter();
emitter.addHandler("start", () => console.log("Started!"));
emitter.addHandler("end", () => console.log("Ended!"));
emitter.emit("end");
emitter.emit("start");