Vue状态管理之Vuex

npm install vuex --save

• state，驱动应用的数据源；
• view，以声明方式将state映射到视图；
• actions，响应在view上的用户输入导致的状态变化。

store/index.js

import Vue from 'vue'
import Vuex from 'vuex'

Vue.use(Vuex)

const state = {
    userList: [1, 2, 3, 4],
    count: 0
}

const getters = {
    getUrlParams: () => () => {
        let url = location.search;
        let theRequest = {};
        if (url.indexOf("?") != -1) {
            var str = url.substr(1), strs;
            strs = str.split("&");
            for (var i = 0; i < strs.length; i++) {
                theRequest[strs[i].split("=")[0]] = unescape(strs[i].split("=")[1]);
            }
        }
        return theRequest;
    },
    getUserList: (state) => {
        //注：这里会缓存，只有执行了 actions，这里的缓存才会更新
        return state.userList;
    }
}
const mutations = {   
    setUserList(state, data){
        // 如果这里的 userList 接口返回，可以用axios请求
        state.userList=data;
    },
    mutationsAddCount(state, n = 0) {
        return (state.count += n)
    },
    mutationsReduceCount(state, n = 0) {   
        console.log(n)
        return (state.count -= n)
    }

}
const actions={
    actionsAddCount(context, n = 0) {
        console.log(context)
        return context.commit('mutationsAddCount', n)
    },
    actionsReduceCount({ commit }, n = 0) {
        return commit('mutationsReduceCount', n)
    },
    commitUserList:({commit}, userList) => commit('setUserList',userList)
}

// const actions = {
//     commitUserList: ({ commit }, userList) => commit('setUserList', userList)
// }

const store = new Vuex.Store({
    state: state,
    getters: getters,
    mutations: mutations,
    actions: actions
})

export default store;

demo:

,<template>
  <div id="demo54">
    <ul>
      <li v-for="(user,index) in userList" :key="index">{{index}}----{{user}}</li>
    </ul>
    <button @click="updateUserList()">更新用户列表</button>
  </div>
</template>

<script>
export default {
  data() {
    return {
      userList: this.$store.getters.getUserList //引入state中的对象
    };
  },
  methods: {
    updateUserList () {
      var item = ["a", "b", "c", "d"];
      this.$store.dispatch('setUserList', item);
    }
  }
};
</script>

<style>
</style>

demo2:

<template>
  <div class="demo55">
    <h3>{{$store.state.count}}</h3>
    <button @click="handleAddClick(10)">增加</button>
    <button @click="handReduceClick(10)">减少</button>
  </div>
</template>

<script>
export default {
  data() {
    return {};
  },
  methods: {
    handleAddClick(n) {    
      this.$store.commit("mutationsAddCount",n)
    },
    handReduceClick(n) {        
      this.$store.commit("mutationsReduceCount", n);
    }
  }
};
</script>

https://www.jianshu.com/p/f393bdd3b03d