state

this.$store.state.   //获取

放在computed里

// 在单独构建的版本中辅助函数为 Vuex.mapState
import { mapState } from 'vuex'

export default {
  // ...
  computed: mapState({
    // 箭头函数可使代码更简练
    count: state => state.count,

    // 传字符串参数 'count' 等同于 `state => state.count`
    countAlias: 'count',

    // 为了能够使用 `this` 获取局部状态，必须使用常规函数
    countPlusLocalState (state) {
      return state.count + this.localCount
    }
  })
}

computed: mapState([
  // 映射 this.count 为 store.state.count
  'count'
])

对象展开运算符

computed: {
  localComputed () { /* ... */ },
  // 使用对象展开运算符将此对象混入到外部对象中
  ...mapState({
    // ...
  })
}

Getter

对于state的计算属性

//normal
computed: {
  doneTodosCount () {
    return this.$store.state.todos.filter(todo => todo.done).length
  }
}

//getter
const store = new Vuex.Store({
  state: {
    todos: [
      { id: 1, text: '...', done: true },
      { id: 2, text: '...', done: false }
    ]
  },
  getters: {
    doneTodos: state => {
      return state.todos.filter(todo => todo.done)
    }
  }
})

this.$store.doneTodos

getter嵌套getter

getters: {
  // ...
  doneTodosCount: (state, getters) => {
    return getters.doneTodos.length
  }
}

this.$store.getters.doneTodosCount

mapGetters

import { mapGetters } from 'vuex'

export default {
  // ...
  computed: {
  // 使用对象展开运算符将 getter 混入 computed 对象中
    ...mapGetters([
      'doneTodosCount',
      'anotherGetter',
      // ...
    ])
  }
}

...mapGetters({
  // 把 `this.doneCount` 映射为 `this.$store.getters.doneTodosCount`
  doneCount: 'doneTodosCount'
})

Mutation

const store = new Vuex.Store({
  state: {
    count: 1
  },
  mutations: {
    increment (state) {
      // 变更状态
      state.count++
    }
  }
})

store.commit('increment')

传参

mutations: {
  increment (state, n) {
    state.count += n
  }
}

store.commit('increment', 10)

payload

// ...
mutations: {
  increment (state, payload) {
    state.count += payload.amount
  }
}

store.commit('increment', {
  amount: 10
})

state.obj = { ...state.obj, newProp: 123 }

组件中提交Mutation

import { mapMutations } from 'vuex'

export default {
  // ...
  methods: {
    ...mapMutations([
      'increment', // 将 `this.increment()` 映射为 `this.$store.commit('increment')`

      // `mapMutations` 也支持载荷：
      'incrementBy' // 将 `this.incrementBy(amount)` 映射为 `this.$store.commit('incrementBy', amount)`
    ]),
    ...mapMutations({
      add: 'increment' // 将 `this.add()` 映射为 `this.$store.commit('increment')`
    })
  }
}

Action

Modules

const moduleA = {
    namesapced=true,
    // ...
    actions: {
        incrementIfOddOnRootSum({ state, commit, rootState }) {
            if ((state.count + rootState.count) % 2 === 1) {
                commit('increment')
            }
        },
        someAction({ dispatch, commit, getters, rootGetters }) {
            getters.someGetter // -> 'foo/someGetter'
            rootGetters.someGetter // -> 'someGetter'

            dispatch('someOtherAction') // -> 'foo/someOtherAction'
            dispatch('someOtherAction', null, { root: true }) // -> 'someOtherAction'

            commit('someMutation') // -> 'foo/someMutation'
            commit('someMutation', null, { root: true }) // -> 'someMutation'
        },
        // 注册全局的，不推荐使用
        wholeAction: {
            root: true,
            handler() { }
        }
    }
}

使用时

// use
computed: {
    ...mapState('some/nested/module', {
    a: state => state.a,
    b: state => state.b
})
},
methods: {
    ...mapActions('some/nested/module', [
    'foo', // -> this.foo()
    'bar' // -> this.bar()
])
}