fes.js/packages/fes-template/src/store/main.js

import { defineStore } from 'pinia';

// useStore could be anything like useUser, useCart
// the first argument is a unique id of the store across your application
export const useStore = defineStore('main', {
    // other options...
    state: () => ({
        // all these properties will have their type inferred automatically
        counter: 0,
        name: 'Eduardo',
        isAdmin: true,
    }),
    actions: {
        increment() {
            this.counter++;
        },
        randomizeCounter() {
            this.counter = Math.round(100 * Math.random());
        },
    },
});