購物車功能描述：

1. 點選+，-按鈕，“已選：xx件”隨之增減

2. checkbox選中時，當前項的已選數量增加到頭部“已選擇xx件”中，未選中時數量不計入

程式碼：

服務端 node+koa+koa-router

server.js

 1 const koa = require('koa')
 2 const router = require('koa-router')
 3 
 4 let server = new koa()
 5 server.listen(8081)
 6 
 7 server.use(async (ctx, next) => {
 8   ctx.set('Access-Control-Allow-Origin', '*')
 
 9 
10   await next()
11 })
12 
13 let r = router()
14 
15 r.get('/list', async ctx => {
16   ctx.body = [{
17       name: 'aa',
18       price: 358,
19       sales: 8531
20     },
21     {
22       name: 'bb',
23       price: 18,
24       sales: 915
25     },
26     {
27       name: 'cc',
28       price: 857,
 
29       sales: 28732
30     },
31     {
32       name: 'dd',
33       price: 3,
34       sales: 5
35     },
36     {
37       name: 'ee',
38       price: 67,
39       sales: 900
40     }
41   ]
42 })
43 
44 server.use(r.routes())

web端 vue+vuex+fetch

src/components/List.vue

 1 <template>
 2   <div class="list">
 3
 
     <div>已選擇 {{state.count}} 件</div>
 4     <ul>
 5       <ListItem v-for="(item,index) in items" :key="index" :data="item"/>
 6     </ul>
 7   </div>
 8 </template>
 9 <script>
10 import ListItem from 'components/ListItem'
11 export default {
12   name: 'List',
13   data() {
14     return {
15       items: [],
16       state: this.$store.state
17     }
18   },
19   components: {
20     ListItem
21   },
22   mounted() {
23     this.getData()
24   },
25   methods: {
26     async getData() {
27       this.items = await (await fetch('http://localhost:8081/list')).json()
28     }
29   }
30 }
31 
32 </script>

src/components/ListItem.vue

 1 <template>
 2     <div class="list-item">
 3       <li>
 4         <span style="width: 80px;display: inline-block;"><input type="checkbox" v-model="isChecked">&nbsp;&nbsp;&nbsp;{{data.name}}</span>
 5         <span style="width: 120px;display: inline-block;">￥: &nbsp;{{data.price}}元</span>
 6         <span style="width: 120px;display: inline-block;">銷量: &nbsp;{{data.sales}}件</span>
 7         <span style="width: 120px;display: inline-block;">已選: &nbsp;{{currentCount}}件</span>
 8         <button @click="addOne">+</button>&nbsp;&nbsp;&nbsp;&nbsp;
 9         <button @click="minusOne">-</button>
10       </li>
11     </div>
12   </template>
13 <script>
14 export default {
15   name: 'ListItem',
16   data() {
17     return {
18       data: {},
19       isChecked: false,
20       currentCount: 1
21     }
22   },
23   created() {
24     this.data = this.$attrs.data
25   },
26   methods: {
27     addOne() {
28       this.currentCount++
29       if (this.isChecked) {
30         this.$store.dispatch('add', 1)
31       }
32     },
33     minusOne() {
34       if (this.currentCount <= 0) return
35       this.currentCount--
36       if (this.isChecked) {
37         this.$store.dispatch('minus', 1)
38       }
39     }
40   },
41   watch: {
42     isChecked() {
43       if (this.isChecked) {
44         this.$store.dispatch('add', this.currentCount)
45       } else {
46         this.$store.dispatch('minus', this.currentCount)
47       }
48     }
49   }
50 }
51 
52 </script>

src/store/index.js

 1 import Vue from 'vue'
 2 import Vuex from 'vuex'
 3 
 4 Vue.use(Vuex)
 5 
 6 export default new Vuex.Store({
 7   strict: true,
 8   state: {
 9     count: 0
10   },
11   mutations: {
12     add(state, arg) {
13       state.count += arg
14     },
15     minus(state, arg) {
16       if (state.count <= 0) {
17         return false
18       }
19       state.count -= arg
20     }
21   },
22   actions: {
23     add({ commit }, arg) {
24       commit('add', arg)
25     },
26     minus({ commit }, arg) {
27       commit('minus', arg)
28     }
29   }
30 
31 })