效果图如下：

store.js代码如下：

import Vue from 'vue'
import Vuex from 'vuex'
import axios from 'axios'
Vue.use(Vuex)
export default new Vuex.Store({
	//状态数据
	state: {
		list:['默认为空']
	},
	//getters可以认为是store的计算属性
	getters: {
		list(state) {
			return state.list
		}
	},
	//存放同步函数方法
	mutations: {
		updateState(state,payload){
			state.list = payload
		},
		setState(state,payload){
			state.list = payload
		}
	},
	//存放异步函数方法
	actions: {
		//async异步
		async getTodos({commit}) {
			const result = await axios.get('http://jsonplaceholder.typicode.com/todos?_limit=10');
			commit('updateState', result.data);
		},
		//Promise异步
		fetchTodos({commit}, params) {
			return new Promise((resolve, reject) => {
				fetch('http://jsonplaceholder.typicode.com/todos?_limit=5')
					.then(res => res.json())
					.then(data => {
						commit('setState', data)
						reject(data)
					})
					.catch(err => reject(err));	//抛出错误回调
			});
		}
		
	}
})

组件App.vue代码如下：

<template>
  <div id="app">
		<!-- 匹配到的路由组件 -->
		<!-- <router-view /> -->
		<h1>下面是store内异步获取的数据</h1>
		<h2>{{list}}</h2>
		<h1> 
			<input type="button" value="同步方法改变数据1" @click="updateState(11111)">
			<input type="button" value="同步方法改变数据2" @click="setState(2222222)">
			<input type="button" value="异步方法获取数据1" @click="getTodos()">
			<input type="button" value="异步方法获取数据2" @click="fetchTodos()">
		</h1>
  </div>
</template>

<script>
//导入vuex辅助函数
import {mapState,mapGetters,mapMutations,mapActions} from 'vuex'
export default {
  name: 'app',
	//这里面存放数据
	data(){
		return{
		}
	},
	//获取计算数据
	computed: mapGetters(['list']),
	methods:{
		//获取store内同步方法
		...mapMutations(['updateState','setState']),
		//获取store内异步方法
		...mapActions(['getTodos','fetchTodos'])
	},
}
</script>

<style>
#app {
  font-family: 'Avenir', Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-align: center;
  color: #2c3e50;
  margin-top: 60px;
}
</style>