Vuex是什么
- Vuex是一个专为Vue.js应用程序开发的状态管理模式。
- 当我们遇到多个组件共享状态时,多层组件的传值非常繁琐,不利于维护,因此我们把组件的共享状态抽取出来,以一个单例模式管理,在这种模式下,不管在哪个组件都可以获取状态或触发行
- 简单来讲就是实现数据共享
安装
npm install vuex --save
使用
main.js
import Vue from 'vue'
import App from './App'
import store from './store'
Vue.config.productionTip = false
/* eslint-disable no-new */
new Vue({
el: '#app',
store,
components: { App },
template: '<App/>'
})
store 文件夹
每一个Vuex应用的核心就是store(仓库),它包含着应用中大部分的状态(state),store是内存机制,而不是缓存机制,当前页面一旦刷新挥着通过路由跳转亦或是关闭,都会导致store初始化。
import Vue from 'vue'
import Vuex from 'vuex'
Vue.use(Vuex)
const store = new Vuex.Store({
state:{
conunt=1,
list:[1,34,5,3,2,3,4,5,1,55,21]
},
getters:{
arr(state){
return state.list.filter(value=>value>5)
},
arr2(state){
return state.list.filter(value=>value<5)
}
},
mutations:{
// 2.修改仓库数据的唯一途径(mutations)
// 注意:这里只能写同步代码,不能写异步代码(setTimeout,setInterval,Promise,Ajax,axios)
increment (state,obj){
state.count+=obj.num
}
}
})
HelloWorld.vue
<script>
import {mapState,mapGetters,mapMutations} from 'vuex'
export default {
name: 'HelloWorld',
computed:{
// 映射形式:对象形式(左边是当前组件内的属性名称、右边是仓库的数据名称)
...mapState({
num:'count',
list:'list'
}),
list(){
return this.$store.state.list
},
age(){
return 19
},
// 映射形式:数组形式(直接写一个名字,代表组件内的属性名和仓库里的数据名称是一致的)
...mapGetters(['arr2'])
},
data () {
return {
msg: 'Welcome to Your Vue.js App'
}
},
methods:{
//修改仓库数据 写法一
...mapMutations({
plus:'increment'
}),
add(){
this.plus({num:2})
},
//修改仓库数据 写法二
plus(){
// this.$store.commit('increment',2) //调用mutations里的函数,修改仓库数据
this.$store.commit({
type:'increment',
num:2
})
}
}
}
</script>
常规项目结构 vuex 模块化
import Vue from 'vue'
import Vuex from 'vuex'
import * as actions from './actions'
import * as getters from './getters'
import state from './state'
import mutations from './mutations'
import createLogger from 'vuex/dist/logger'
Vue.use(Vuex)
const debug = process.env.NODE_ENV !== 'production'
export default new Vuex.Store({
actions,
getters,
state,
mutations,
strict: debug,
plugins: debug ? [createLogger()] : []
})
state.js vuex 初始数据
const state = {
singer: {},
playlist: [],
sequenceList: [],
currentIndex: -1,
topList: {},
}
export default state
getters.js 提交方法
export const singer = state => state.singer
export const playing = state => state.playing
export const currentIndex = state => state.currentIndex
export const currentSong = (state) => {
return state.playlist[state.currentIndex] || {}
}
mutation-type.js 定义mutation 方便后期修改
export const SET_SINGER = 'SET_SINGER'
export const SET_PLAYING_STATE = 'SET_PLAYING_STATE'
export const SET_FULL_SCREEN = 'SET_FULL_SCREEN'
export const SET_TOP_LIST = 'SET_TOP_LIST'
mutations.js 执行方法 注:mutations 只能用于同步操作
import * as types from './mutation-types'
const mutations = {
[types.SET_SINGER](state, singer) {
state.singer = singer
},
[types.SET_PLAYING_STATE](state, flag) {
state.playing = flag
},
[types.SET_FULL_SCREEN](state, flag) {
state.fullScreen = flag
},
}
export default mutations
actions.js 执行mutation 方法 注:可执行异步操作 本质是通过提交mutation 来改变 state
(mutation是修改state数据的唯一途径)
import * as types from './mutation-types'
export const randomPlay = function ({commit}, {list}) {
commit(types.SET_SEQUENCE_LIST, list)
commit(types.SET_PLAYLIST, list)
commit(types.SET_CURRENT_INDEX, 0)
commit(types.SET_FULL_SCREEN, true)
commit(types.SET_PLAYING_STATE, true)
}
vuex 的使用场景
- 应用遇到多个组件共享状态时,使用vuex
- 涉及非父子组件之间跨组件共享数据
- 场景:登录信息、购物车、当前播放的音频视频