store.ts

import { defineStore } from 'pinia'

export const useMainStore = defineStore('main', {
  // 用于存储数据
  // 必须是箭头函数(需要ts类型推导)
  state: () => {
    return {}
  },
})

HelloWorld.vue

<template>
  <p>Count: {{ mainStroe.count }}</p>
</template>

<script setup lang="ts">
  import { useMainStore } from './store.ts'

  const mainStroe = useMainStore()
</script>