createSubscriber docs are too complex

[olehmisar]

https://svelte.dev/docs/svelte/svelte-reactivity#createSubscriber

It requires the knowledge of window.matchMedia and addEventListener(window.matchMedia(), "change").

A simpler example would be better

[ViggieM]

I agree 😀 Maybe an example how to use the MediaQuery class would make it a little bit more clear, at least to me :)

[gyzerok]

Yeah, would also agree with that. We have the following reactivity helper to update various places in the UI based on current time. To me it seems much simpler.

export const now = new (class Now {
  private subscribe: () => void = () => {};

  constructor() {
    this.subscribe = createSubscriber((update) => {
      const intervalId = setInterval(update, 1000);
      return () => {
        clearInterval(intervalId);
      };
    });
  }

  get current(): number {
    this.subscribe();

    return Date.now();
  }
})();