vue实现购物车功能的方法

new Vue({
 el: "#app",
 data: {
 cIndex: 0,
 lists: [
  {
  title: "推荐商品",
  goods: [
   {
   id: 0,
   img: './images/goods.png',
   name: '散称樱桃1',
   price: '10.00',
   num: 0
   },
   {
   id: 1,
   img: './images/goods.png',
   name: '散称樱桃1',
   price: '10.00',
   num: 0
   }
 
  ]
  },
  {
  title: "推荐商品",
  goods: [
   {
   id: 2,
   img: './images/goods.png',
   name: '散称樱桃2',
   price: '20.00',
   num: 0
   },
   {
   id: 3,
   img: './images/goods.png',
   name: '散称樱桃2',
   price: '20.00',
   num: 0
   },
  ]
  },
 ],
 carArr: [],
 appearCar: false,
 },
 computed:{
 alltotal:function () {
  var alltotal = 0;
  var allNum = 0;
  for(var i = 0,len = this.lists.length;i<len;i++){
  for(var j = 0,goodsLen = this.lists[i].goods.length;j<goodsLen;j++){
   alltotal += parseInt(this.lists[i].goods[j].num)*parseFloat(this.lists[i].goods[j].price);
   allNum += parseInt(this.lists[i].goods[j].num);
  }
  }
  return [alltotal,allNum]
 },
 },
 methods: {
 leftTap: function (index) {
  this.cIndex = index
 },
 showCar: function () {
  if (this.carArr.length == 0) {
  this.appearCar = false
  } else {
  this.appearCar = !this.appearCar
  }
 
 },
 //商品数量加
 addNum: function (data) {
  data.num++;
  var carArr = this.carArr;
  var isCar = false;
  if (carArr == 0) {
  carArr.push(data)
  }
  for (var i = 0, len = carArr.length; i < len; i++) {
  if (data.id == carArr[i].id) {
   isCar = true
  }
  }
  if (!isCar) {
  carArr.push(data)
  }
 },
 reduceNum: function (data) {
  if (data.num <= 0) return;
  var carArr = this.carArr;
  data.num--;
  var isCar = false;
  for (var i = 0, len = carArr.length; i < len; i++) {
  if (carArr[i].num <= 0) {
   carArr.splice(i, 1)
  }
  }
 },
 carAddNum: function (index) {
  this.carArr[index].num++
 },
 carReduceNum: function (index) {
  this.carArr[index].num--;
  if (this.carArr[index].num <= 0) {
  this.carArr.splice(index, 1)
  }
  if (this.carArr.length == 0) {
  this.appearCar = !this.appearCar
  }
 },
 // 清空
 delCar: function () {
  confirm('确定清空购物车吗&#63;');
  var cur = this.cIndex;
  var goods = this.lists[cur].goods
  if (true) {
  this.carArr = [];
  this.appearCar = !this.appearCar;
  for(var i = 0,len = this.lists.length;i<len;i++){
   for(var j = 0,goodsLen = this.lists[i].goods.length;j<goodsLen;j++){
   this.lists[i].goods[j].num=0;
   }
  }
  }
 },
 Settlement:function () {
  if(this.alltotal[0]<=0){
  console.log('我不动')
  }else{
  window.location.href = 'cashierPay.html'
  }
 }
 }
})

<div id="app" v-cloak>
 <div class='box'>
 <div class='boxleft'>
  <div class='boxla'>
  <img src='./images/sm.png'/>
  <span>扫码</span>
  </div>
  <ul class='boxlbox'>
  <template v-for="(item,index) in lists">
   <li @click='leftTap(index)' :class="{boxlb_cheak:cIndex==index}" class='boxlb'>
   <span class='boxlb_inner' :class="{boxlb_inner_cheak:cIndex==index}">{{item.title}}</span>
   </li>
  </template>
  </ul>
 </div>
 <ul class='boxright'>
  <li class='boxri' v-for="(item,index) in lists[cIndex].goods">
  <img class='boxri_img' :src='item.img'/>
  <div class='boxri_text'>
   <div class='boxrit_left'>
   <p class='boxritl_name'>{{item.name}}</p>
   <p class='boxritl_price'>￥{{item.price}}</p>
   </div>
   <div class='boxrit_right'>
   <img @click='reduceNum(item)' v-show="item.num>0" class='boxrit_right_img' src='./images/minus.png'/>
   <span class='boxrit_right_num' v-show="item.num>0">{{item.num}}</span>
   <img @click='addNum(item)' class='boxrit_right_img' src='./images/add.png'/>
   </div>
  </div>
  </li>
 </ul>
 </div>
 <footer class='footer'>
 <div class='cartImgBox'>
  <img class='cartImg' src='./images/car.png' @click='showCar'/>
  共{{alltotal[1]}}件商品
 </div>
 <div class='footerb'>￥{{alltotal[0]}}</div>
 <div @click='Settlement' class='footerc'>结算</div>
 </footer>
 <!-- 购物车 -->
 
 <div class='shop-car-mask' v-show="appearCar">
 <div class='shop-com'>
  <div class='shop-title'>
  <span>已选商品</span>
  <span @click="delCar">清空</span>
  </div>
  <ul class="car-shopList">
  <template v-for='(item,index) in carArr'>
   <li class='car-list'>
   <div class='car-img'>
    <img :src='item.img'/>
   </div>
   <div class='car-name'>{{item.name}}</div>
   <div class='car-num'>￥{{item.price}}</div>
   <div class='boxrit_right2'>
    <img @click='carReduceNum(index)' class='boxrit_right_img2' src='./images/minus.png'/>
    <span class='boxrit_right_num2'>{{item.num}}</span>
    <img @click='carAddNum(index)' class='boxrit_right_img2' src='./images/add.png'/>
   </div>
   </li>
  </template>
  </ul>
 </div>
 </div>
</div>