astro/examples/with-nanostores/src/store/counter.js

import { atom } from 'nanostores';

const initialValue = { value: 0 };

const counter = atom(initialValue);

function increaseCounter() {
  counter.set({ value: counter.get().value + 1 });
}

function decreaseCounter() {
  counter.set({ value: counter.get().value - 1 });
}

export { counter, increaseCounter, decreaseCounter };