store.ts

import { createSignal, createResource } from "solid-js";
import { createMutable } from "solid-js/store";

export const list = createMutable({
  items: JSON.parse(
    window.localStorage.getItem("cart") ?? "[]"
  ),
  get count() {
    return this.items.length;
  },
  addItem(item) {
    this.products.push(item);
  },
  clear() {
    this.items = [];
  },
});

export const [count, setCount] = createSignal(0);

export const [items] = createResource(
  () => fetch("your api ...").then((res) => res.json()),
  {
    initialValue: [],
  }
);