Vuex是什麼
- Vuex是一個專爲Vue.js應用程序開發的狀態管理模式。
- 當我們遇到多個組件共享狀態時,多層組件的傳值非常繁瑣,不利於維護,因此我們把組件的共享狀態抽取出來,以一個單例模式管理,在這種模式下,不管在哪個組件都可以獲取狀態或觸發行
- 簡單來講就是實現數據共享
安裝
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 文件夾
每一個Vuex應用的核心就是store(倉庫),它包含着應用中大部分的狀態(state),store是內存機制,而不是緩存機制,當前頁面一旦刷新揮着通過路由跳轉亦或是關閉,都會導致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.修改倉庫數據的唯一途徑(mutations)
// 注意:這裏只能寫同步代碼,不能寫異步代碼(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:對象形式(左邊是當前組件內的屬性名稱、右邊是倉庫的數據名稱)
...mapState({
num:'count',
list:'list'
}),
list(){
return this.$store.state.list
},
age(){
return 19
},
// 映射形式:數組形式(直接寫一個名字,代表組件內的屬性名和倉庫裏的數據名稱是一致的)
...mapGetters(['arr2'])
},
data () {
return {
msg: 'Welcome to Your Vue.js App'
}
},
methods:{
//修改倉庫數據 寫法一
...mapMutations({
plus:'increment'
}),
add(){
this.plus({num:2})
},
//修改倉庫數據 寫法二
plus(){
// this.$store.commit('increment',2) //調用mutations裏的函數,修改倉庫數據
this.$store.commit({
type:'increment',
num:2
})
}
}
}
</script>
常規項目結構 vuex 模塊化
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 初始數據
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 定義mutation 方便後期修改
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 執行方法 注:mutations 只能用於同步操作
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 執行mutation 方法 注:可執行異步操作 本質是通過提交mutation 來改變 state
(mutation是修改state數據的唯一途徑)
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 的使用場景
- 應用遇到多個組件共享狀態時,使用vuex
- 涉及非父子組件之間跨組件共享數據
- 場景:登錄信息、購物車、當前播放的音頻視頻