4.mapMutations

//store/index.js
 mutations: {
    myIncrease(state){
      state.count++
    },
    myDecrease(state){
      state.count--
    }
  },
 //vue
<template>
  <div class="home">
      <h2>{{this.$store.state.count}}</h2>
      <button @click="myIncrease">增加</button>
      <button @click="myDecrease">减少</button>
  </div> 
</template>
<script>
import {mapMutations} from 'vuex'
export default {
  name: 'home',
  methods:{
    ...mapMutations(['myIncrease','myDecrease']), 
    add(){
      this.myIncrease()
    },
    reduce(){
      this.myDecrease()
    }
  },
}
</script>