JavaScript
yarn add pinia
// or with npm
npm i pinia

JavaScript
import { createPinia } from 'pinia'

const pinia = createPinia()

export default pinia

JavaScript
// main.js文件中定义
import pinia from './stores/index'

createApp(App).use(pinia).mount('#app')

JavaScript
import { defineStore } from 'pinia'

// defineStore 本身的返回值是一个函数
// 习惯用useXXX来命名 => 规范
const useCounter = defineStore("counter",{
    state:()=> ({
        count:999
    })
})

export default useCounter

JavaScript
<template>
  <div class="home">
    <h2>Home view</h2>
    <h2>count: {{ counterStore.count }}</h2>
  </div>
</template>

<script setup>
import useCounter from '@/stores/counter';

const counterStore = useCounter()
</script>

<style scoped>
</style>

JavaScript
const counterStore = useCounter()

counterStore.count++
counterStore.name = "xiong"

JavaScript
const counterStore = useCounter()
counterStore.$reset()

JavaScript
function changeStateClick(){
    // 1 一个一个修改状态
    // userStore.name = "xiaoxiong"
    // userStore.age = 18
    // userStore.level = 9999

    // 2 一次性修改多个状态
    userStore.$patch({
      name:"xx",
      age:20
    })
  }

JavaScript
counterStore.$state = {
    counter:1,
    name:"xxiong"
}

JavaScript
const useCounter = defineStore("counter",{
    state:()=> ({
        count:999,
        friends:[
            { id:1,name:"xiong" },
            { id:2,name:"xx" },
            { id:3,name:"xxiong" },
        ]
    }),
    getters:{
        // 1 基本使用
        doubleCount(state){
            return state.count * 2
        },
        // 2 一个getter引入另外一个getter
        doubleCountAddOne(){
            // 通过this访问 this绑定store实例
            return this.doubleCount + 1
        },
        // 3 getters也支持返回一个函数
        getFriendById(state){
            return function(id) {
                // 高阶js写法
                return state.friends.find(item => item.id === id )

                // 普通写法
                // for(let i = 0;i<state.friends.length;i++){
                //     const friend = state.friends[i]
                //     if(friend.id === id){
                //         return friend
                //     }
                // }
            }
        },
        // 4 getters中使用到别的store中的数据
        showMsg(state){
            // 展示 count  和 user内的信息
            // 在上面 导入 user包
            // 1 获取user信息
            const useStore = useUser()
            // 2 获取自己信息 state

            // 3 拼接信息
            return `name:${useStore.name}-count:${state.count}`
        }
        
    }
})

JavaScript
<h2>doubleCount: {{ countStore.doubleCount }}</h2>
<h2>doubleCountAddOne: {{ countStore.doubleCountAddOne }}</h2>
<h2>friend-2: {{ countStore.getFriendById(2) }}</h2>
<h2>拼接counter里面的count和user里面的名字: showMsg:{{ countStore.showMsg }}</h2>

JavaScript
doubleCountAddOne(){
    // 通过this访问 this绑定store实例
    return this.doubleCount + 1
},

JavaScript
// 4 getters中使用到别的store中的数据
showMsg(state){
    // 展示 count  和 user内的信息
    // 在上面 导入 user包
    // 1 获取user信息
    const useStore = useUser()
    // 2 获取自己信息 state

    // 3 拼接信息
    return `name:${useStore.name}-count:${state.count}`
}

JavaScript
 // 3 getters也支持返回一个函数
getFriendById(state){
    return function(id) {
        // 高阶js写法
        return state.friends.find(item => item.id === id )

        // 普通写法
        // for(let i = 0;i<state.friends.length;i++){
        //     const friend = state.friends[i]
        //     if(friend.id === id){
        //         return friend
        //     }
        // }
    }
},

JavaScript
actions:{
    // 用来定义方法,这里不会给我们传进来一个state,
    // 他用来传递参数
    increment() {
        this.count++
    },
    // 如:下示例
    incrementAdd(num){
        this.count += num
    }
}

JavaScript
 actions:{
    async fetchHomeMultidata(){
        const res = await fetch("http://xxxx:8000/home/")
        const data = await res.json()
        // console.log(data) // 拿到数据
        this.banners = data.data.banner.list
        this.recommends = data.data.recommend.list
    }
}