//vuex/index.js
import Vue from 'vue';
import Vuex from 'vuex';
Vue.use(Vuex);
const state = {
  bookList: [
   {id: 1, name: '西游記'},{id: 2, name: '水滸傳'},
   {id: 3, name: '紅樓夢'},{id: 4, name: '三國演義'}
  ]
}
export default new Vuex.Store({
  state
})

//Home.vue
<p v-for='item in bookList'>{ {item.name} }<p/>

//方法一：通過computed的計算屬性直接賦值，computed屬性可以在輸出前，對data中的值進行改變，我們就利用這種特性把state值賦值給vue模板中的data進行使用
computed: {
  bookList( ) {
   return this.$store.state.bookList;
  }
}

//方法二：通過mapState的對象來賦值
import { mapState } from 'vuex';//首先在組件內引入mapState
computed: {
  ...mapState(['bookList'])
}

//vuex/index.js
const mutations = {
  ADD_ITEM(state,item) {
   state.bookList.push(item)
  }
}
const mutations = {
  ADD_ITEM(state,item) {
   state.bookList.push(item)
  },
  DEL_ITEM(state,id) {
   state.bookList.map((v,i)=> {
     if(v.id == id){
      state.bookList.splice(i,1)
     }
   })
  }
}
const actions = {
  add_item({commit},item) {
   commit('ADD_ITEM',item)
  },
  del_item({commit},id) {
   commit('DEL_ITEM',id)
  }
}
export default new Vuex.Store({
  state,mutations,actions
})
//Home.vue
<button @click='add_item'>ADD</button>
<p v-for='item in bookList' @click='delItem(item.id)'>{ {item.name} }<p/>

import { mapState, } from 'vuex';

computed: {
  ...mapState(['bookList'])
}
methods: {
  add_item() {
   let newObject = {id:this.bookList.length,name:'葫蘆娃'}
   this.$store.dispatch('add_item',newObject)
  },
  delItem(id) {
   this.$store.dispatch('del_item',id)
  }
}

//vuex/index.js
const getters = {
  newBookList:function( state ){
   return JSON.parse(JSON.stringify(state.bookList)).splice(0,1)
  }
}

mounted( ) {
  console.log(this.$store.getters.newBookList)
  console.log(this.bookList)
}