前端学习（2199）：vuex-getter的使用详解

app.vue

<template>
  <div id="app">
  <h2>{{message}}</h2>
  <h2>{{$store.state.counter}}</h2>
   <button @click="addtion">+</button>
   <button @click="subtraction">-</button>

   <hello-vuex :counter="counter"></hello-vuex>
    <h2>{{$store.state.counter*$store.state.counter}}</h2>
      <h2>{{$store.getters.more20stu}}</h2>
  </div>
</template>

<script>
import HelloVuex from './components/HelloWorld.vue'
export default {
  name: 'App',
  components:{
    HelloVuex
  },
  data(){
    return {
      message:'我是app组件',
      counter:1000
    }
  },
  
  methods:{
    addtion(){
      this.$store.commit('increment')
    },
    subtraction(){
      this.$store.commit('decrement')
    }
  }
}
</script>

<style>



</style>

main.js

// The Vue build version to load with the `import` command
// (runtime-only or standalone) has been set in webpack.base.conf with an alias.
import Vue from 'vue'
import App from './App'
import router from './router'
import store from './store'

Vue.config.productionTip = false



/* eslint-disable no-new */
new Vue({
    el: '#app',
    router,
    store,
    components: { App },
    template: '<App/>'
})

index.js

import Vue from 'vue'
//第一步
import Vuex from 'vuex'

Vue.use(Vuex)

//创建对象
const store = new Vuex.Store({
    state: {
        counter: 1000
    },
    mutations: {
        increment(state) {
            state.counter++
        },
        decrement(state) {
            state.counter--
        },
    },
    getters: {

    },
    modules: {

    }
})

//
export default store

index.js

import Vue from 'vue'
import Router from 'vue-router'
import HelloWorld from '@/components/HelloWorld'

Vue.use(Router)

export default new Router({
  routes: [
    {
      path: '/',
      name: 'HelloWorld',
      component: HelloWorld
    }
  ]
})

index.js

import Vue from 'vue'
//第一步
import Vuex from 'vuex'

Vue.use(Vuex)

//创建对象
const store = new Vuex.Store({
    state: {
        counter: 1000,
        students: [{
            id: 110,
            name: 'geyao',
            age: 18,
        }, {
            id: 111,
            name: 'geyao',
            age: 18,
        }, {
            id: 112,
            name: 'geyao',
            age: 22,
        }, {
            id: 113,
            name: 'geyao',
            age: 21,
        }, ]
    },
    mutations: {
        increment(state) {
            state.counter++
        },
        decrement(state) {
            state.counter--
        },
    },
    getters: {
        powerCouter(state) {
            return state.counter * state.counter
        },
        more20stu(state) {
            return state.students.filter(s => {
                return s.age > 20
            })
        },
        more20stu(state) {
            return state.students.filter(s =>
                s.age > 20
            ).length
        },
        moreAgestu(state) {
            return function(age) {
                return state.students.filter(s => s.age > 20)
            }
        }
    },
    modules: {

    }
})

//
export default store

HelloWorld.js

<template>
  <div id="app">

  <h2>{{$store.state.counter}}</h2>
     <h2>{{$store.getters.powerCouter}}</h2>
       <h2>{{$store.getters.more20stu}}</h2>
          <h2>{{$store.getters.more20stu.length}}</h2>
  </div>
</template>

<script>

export default {
  name: 'HelloVuex',
  props:{
    counter:Number
  },
  data(){
    return {

    }
  }
}
</script>

<style>



</style>

运行结果

运行结果