Simple notifier for Peter

Notifier.ts

interface Handler<T> {
    (payload: T);
}

export default class Notifier<T> {
    protected handlers: Set<Handler<T>> = new Set();

    subscribe(handler: Handler<T>) {
        this.handlers.add(handler);
    }

    unsubscribe(handler: Handler<T>) {
        this.handlers.delete(handler);
    }

    unsubscribeAll() {
        this.handlers.clear();
    }

    notify(payload: T) {
        for (const handler of this.handlers) {
            handler(payload);
        }
    }
}