Vue--- VueX基础 （Vuex结构图数据流向）1.1

Vuex基础 

https://vuex.vuejs.org/zh-cn

state --> view --> action -> state

多组件共享状态， 之前操作方式，由父组件传递到各个子组件。 当路由等加入后，会变得复杂。 引入viewx 解决共享问题。

原vue结构图

 

vuex结构图

Vuex对象结构 （state，mutations，getters，actions） 

state 对象数据

mutations 操作变更state数据

getters 计算state

actions  触发mutations

★学习之后分析数据流向图★

安装

npm install --save vuex

调试

 目标

代码1  ：原vue实现计数器

 app.uve

<template>
<div>
  <p>点击次数{{count}}， 奇偶数:{{eventOrOdd}}</p>
  <button @click="increment">+</button>
  <button @click="decrement">-</button>
  <button @click="incrementIfOdd">奇数加</button>
  <button @click="incrementAsync">异步加</button>
</div>
</template>

<script>
export default {
  data () {
    return {
      count: 0
    }
  },
  computed: {
    eventOrOdd () {
      return this.count % 2 === 0 ? '偶数' : '奇数'
    }
  },
  methods: {
    increment () {
      const count = this.count
      this.count = count + 1
    },
    decrement () {
      const count = this.count
      this.count = count - 1
    },
    incrementIfOdd () {
      const count = this.count
      if (count % 2 === 1) {
        this.count = count + 1
      }
    },
    incrementAsync () {
      setTimeout(() => {
        const count = this.count
        this.count = count + 1
      }, 1000)
    }
  }
}
</script>

<style>

</style>

代码2： VUEX实现

 store.js

/**
 * Created by infaa on 2018/9/22.
 */
import Vue from 'vue'
import Vuex from 'vuex'

Vue.use(Vuex)

const state = { // 初始化状态
  count: 0
}
const mutations = {
  INCREMENT (state) {
    state.count++
  },
  DECREMENT (state) {
    state.count--
  }
}

const actions = {
  increment ({commit}) {
    commit('INCREMENT')
  },
  decrement ({commit}) {
  commit('DECREMENT')
  },
  incrementIfOdd ({commit, state}) {
    if (state.count%2 === 1) {
      commit('INCREMENT')
    }
  },
  incrementAsync ({commit}) {
    setTimeout( () => {
      commit('INCREMENT')
    }, 1000)
  }
}

const getters = {
  eventOrOdd (state) {
    return state.count % 2 === 0 ? '偶数' : '奇数'
  }
}

export default new Vuex.Store({
  state, // 状态对象
  mutations, // 更新state函数的对象
  actions,// dispatch 对应actiong
  getters  // 对应computed 中getters
})

main.js

/**
 * Created by infaa on 2018/9/19.
 */
import Vue from 'vue'
import App from './App'
import store from './store'

/* eslint-disable no-new */

new Vue({
  el: '#app',
  components: {App},
  template: '<App/>',
  store // 所有组件对象多了一个属性$store
})

app.vue

<template>
<div>
  <!--<p>点击次数{{count}}， 奇偶数:{{eventOrOdd}}</p>-->
  <p>点击次数{{$store.state.count}}， 奇偶数:{{eventOrOdd}}</p>
  <button @click="increment">+</button>
  <button @click="decrement">-</button>
  <button @click="incrementIfOdd">奇数加</button>
  <button @click="incrementAsync">异步加</button>
</div>
</template>

<script>
export default {
//  data () {
//    return {
//      count: 0
//    }
//  },
  computed: {
    eventOrOdd () {
//      return this.count % 2 === 0 ? '偶数' : '奇数'
      return this.$store.getters.eventOrOdd // js中要写this，模版中不用直接写$store
    }
  },
  methods: {
    increment () {
      this.$store.dispatch('increment')
    },
    decrement () {
//      const count = this.count
//      this.count = count - 1
      this.$store.dispatch('decrement')
    },
    incrementIfOdd () {
      this.$store.dispatch('incrementIfOdd')
//      const count = this.count
//      if (count % 2 === 1) {
//        this.count = count + 1
//      }
    },
    incrementAsync () {
      this.$store.dispatch('incrementAsync')
//      setTimeout(() => {
//        const count = this.count
//        this.count = count + 1
//      }, 1000)
    }
  }
}
</script>

<style>

</style>

 代码3 优化app.js

app.uve 如果对应名不同，由[ ] 改为｛｝即可

<template>
<div>
    <!-- <h2>点击的个数:{{count}}</h2> -->
    <!-- <h3>{{eventOrOdd}}</h3> -->
    <!-- Vuex 版本  -->
    <h2>点击次数{{$store.state.count}}， 奇偶数:{{eventOrOdd}}</h2>
    <button @click="increment">+</button>
    <button @click="decrement">-</button>
    <button @click="incrementIfOdd">奇数+</button>
    <button @click="incrementAsync">异步加</button>
</div>
</template>

<script type="text/ecmascript-6">
import {mapState, mapGetters, mapActions} from 'vuex'
    // export default{
    //     data(){
    //         return{
    //             count:0
    //         }
    //     },
    //     computed:{
    //         eventOrOdd(count){
    //         //     return this.count % 2 === 0?'偶数':'奇数'
    //             return this.$store.getters.eventOrOdd
    //         }
             
    //     },
    //     methods:{
    //         increment () {
    //             // const count = this.count;
    //             // this.count = count+1
                
    //             this.$store.dispatch('increment')
    //         },
    //         decrement (){
    //             // const count = this.count;
    //             // this.count = count -1 
    //             this.$store.dispatch('decrement')
    //         },
    //         incrementIfOdd () {
    //             // const count = this.count;
    //             // if(count % 2 === 1 ){
    //             //     this.count = count + 1
    //             // }
    //             this.$store.dispatch('incrementIfOdd');
    //         },
    //         incrementAsync () {
    //           // setTimeout(() => {
    //             // const count = this.count
    //             // this.count = count + 1
    //           // }, 1000)
    //           this.$store.dispatch('incrementAsync')
    //         }
    //     }
    //     };
        // 优化 App.vue   代码格式 
    export default{
        computed:{
            ...mapState['count'],
            ...mapGetters['eventOrOdd']
        },
        methods:{
            ...mapActions(['increment','decrement','incrementIfOdd','incrementAsync'])
        }
    };
    
    
</script>

<style type="stylus" rel="stylesheet/stylus">
    
</style>

官方另一个案例购物车， store以目录结构呈现

https://github.com/vuejs/vuex/tree/dev/examples/shopping-cart