> [!info]
> **Observer** is a behavioral design pattern that lets you define a subscription mechanism to notify multiple objects about any events that happen to the object they’re observing.
[Refactoring Guru: Observer](https://refactoring.guru/design-patterns/observer)
Kunkun does not implement any observer pattern yet, but it depends on [Svelte store](https://svelte.dev/docs/svelte/stores).
Svelte store has a `subscribe()` method.
```ts
import { writable } from 'svelte/store';
const count = writable(0);
count.subscribe((value) => {
console.log(value);
}); // logs '0'
count.set(1); // logs '1'
count.update((n) => n + 1); // logs '2'
```