@highloop/feedback-internal/src/lib/observer.ts

export let createObservable = <T>() => {
  let listeners: ((d: T) => unknown)[] = [];

  return {
    register: (listener: (d: T) => unknown) => {
      listeners.push(listener);

      return () => {
        listeners = listeners.filter(l => l != listener);
      };
    },
    fire: (data?: T) => {
      listeners.forEach(l => l(data));
    }
  };
};