module

由于使用单一状态树，应用的所有状态会集中到一个比较大的对象。当应用变得非常复杂时，store 对象就有可能变得相当臃肿。

为了解决以上问题，Vuex 允许我们将 store 分割成模块（module）。每个模块拥有自己的 state、mutation、action、getter。

store.js

import Vue from 'vue'
import Vuex from 'vuex'Vue.use(Vuex)const moduleA = {state: {countA: 0},getters: {totalA: (state) => (symbol) => {return (symbol || '$') + state.countA}},mutations: {incrementA(state, payload){state.countA += (payload || 1);}}
}const moduleB = {state: {countB: 0},getters: {totalB: (state) => (symbol) => {return (symbol || '$') + state.count}},mutations: {incrementB(state, payload){state.countB += (payload || 1);}}
}
const store = new Vuex.Store({modules: {moduleA,moduleB}
})export default store

component

<input type="button" value="increment" @click="add()"/>
<span>{{countA}}</span>
<script>import {mapState, mapMutations, mapActions} from 'vuex';export default {methods: {...mapMutations(['incrementA']),...mapMutations({add: 'incrementA'})},computed: {...mapState({countA: state => state.moduleA.countA})}}
</script>

小结

• 每个模块中的 state、mutation、action、getter 都是独立的作用域
• 不同模块间的 state、getter 的属性存在同级同名的情况下会报错
• mutation、action 等方法同名的话会所有模块一起触
• 解决以上问题，需要给每个模块再做一层作用域分离——命名空间

命名空间

store.js

import Vue from 'vue'
import Vuex from 'vuex'Vue.use(Vuex)const moduleA = {namespaced: true,state: {count: 0},getters: {total: (state) => (symbol) => {return (symbol || '$') + state.count}},mutations: {increment(state, payload){state.count += (payload || 1);}}
}const moduleB = {namespaced: true,state: {count: 0},getters: {total: (state) => (symbol) => {return (symbol || '$') + state.count}},mutations: {increment(state, payload){state.count += (payload || 1);}}
}
const store = new Vuex.Store({modules: {moduleA,moduleB}
})export default store

带命名空间的绑定函数

methods: {...mapMutations(['moduleA/increment']),...mapMutations({add: 'moduleA/increment'})
},
computed: {...mapState({countA: state => state.moduleA.count})
}