Vue.js 3 Guide: Composition API and Nuxt

<script setup>
import { ref } from 'vue';

const count = ref(0);
</script>

<template>
  <button @click="count++">{{ count }}</button>
</template>

import { defineStore } from 'pinia';

export const useUserStore = defineStore('user', {
  state: () => ({ user: null }),
  actions: {
    setUser(user) { this.user = user; }
  }
});