Vue实现商品分类菜单数量提示功能

<template>
 <div class="goods">
  <div class="menu-wrapper" ref="menuScroll">
   <ul>
    <!--专场-->
    <li class="menu-item" :class="{'current':currentIndex===0}" @click="selectMenu(0)">
     <p class="text">
      <img :src="container.tag_icon" v-if="container.tag_icon" class="icon">
      {{container.tag_name}}
     </p>
    </li>
    <li
     class="menu-item"
     v-for="(item,index) in goods"
     :class="{'current':currentIndex===index+1}"
     @click="selectMenu(index+1)"
    >
     <p class="text">
      <img :src="item.icon" v-if="item.icon" class="icon">
      {{item.name}}
     </p>
     <i class="num" v-show="calculateCount(item.spus)">{{calculateCount(item.spus)}}</i>//通过i标签展示数量
    </li>
   </ul>
  </div>
  <!-- 右侧商品列表 -->
  <div class="foods-wrapper" ref="foodScroll">
   <!--专场-->
   <ul>
    <li class="container-list food-list-hook">
     <div v-for="item in container.operation_source_list">
      <img :src="item.pic_url">
     </div>
    </li>
    <!-- 具体分类-->
    <li v-for="item in goods" class="food-list food-list-hook">
     <h3 class="title">{{item.name}}</h3>
     <!--具体商品列表-->
     <ul>
      <li v-for="food in item.spus" class="food-item">
        
       <div class="icon" :style="head_bg(food.picture)"></div>

       <div class="content">
        <h3 class="name">{{food.name}}</h3>
        <p class="desc" v-if="food.description">{{food.description}}</p>
        <div class="extra">
         <span class="saled">{{food.month_saled_content}}</span>
         <span class="praise">{{food.praise_content}}</span>
        </div>
        <img
         class="product"
         :src="food.product_label_picture"
         v-show="food.product_label_picture"
        >
        <p class="price">
         <span class="text">￥{{food.min_price}}</span>
         <span class="unit">/{{food.unit}}</span>
        </p>
       </div>
       <div class="cartcontrol-wrapper">
        <Cartcontrol :food="food"></Cartcontrol>
       </div>
      </li>
     </ul>
    </li>
   </ul>
  </div>
  <Shopcart :poiInfo="poiInfo" :selectFoods="selectFoods"></Shopcart>
 </div>
</template>

<script>
import BScroll from "better-scroll";
import Shopcart from "components/Shopcart/Shopcart";
import Cartcontrol from "components/Cartcontrol/Cartcontrol";

export default {
 data() {
  return {
   container: {},
   goods: [],
   poiInfo: {},
   listHeight: [],
   menuScroll: {},
   foodScroll: {},
   scrollY: 0
  };
 },
 components: {
  BScroll,
  Shopcart,
  Cartcontrol

 },
 created() {
  this.$axios
   .get("api/goods")
   .then(response => {
    let json = response.data;
    if (json.code === 0) {
     // 重点
     this.container = json.data.container_operation_source;
     this.goods = json.data.food_spu_tags;
     console.log(this.goods)
     this.poiInfo = json.data.poi_info;
     this.$nextTick(function() {
      this.initScroll();
      // 左右联动
      // 右->左
      // 计算区间
      this.caculateHeight();
     });
    }
   })
   .catch(function(error) {
    // handle error
    console.log(error);
   });
 },
 computed: {
  // 根据右侧判断左侧index
  currentIndex() {
   for (let i = 0; i < this.listHeight.length; i++) {
    let start = this.listHeight[i];
    let end = this.listHeight[i + 1];
    if (this.scrollY >= start && this.scrollY < end) {
     return i;
    }
   }
   return 0;
  },
  selectFoods() {
   let foods = [];
     this.goods.forEach(good => {
     good.spus.forEach(food => {
      if (food.count > 0) {
       foods.push(food);
      }
     }); 
    });
   return foods;
  }
 },
 methods: {
  head_bg(imgName) {
   return "background-image: url(" + imgName + ");";
  },
  initScroll() {
   this.menuScroll = new BScroll(this.$refs.menuScroll, {
    click: true
   });
   this.foodScroll = new BScroll(this.$refs.foodScroll, {
    probeType: 3,
    click: true
   });
   this.foodScroll.on("scroll", pos => {
    this.scrollY = Math.abs(Math.round(pos.y));
   });
  },
  caculateHeight() {
   let foodList = this.$refs.foodScroll.getElementsByClassName(
    "food-list-hook"
   );
   let height = 0;
   this.listHeight.push(height);
   for (let i = 0; i < foodList.length; i++) {
    height += foodList[i].clientHeight;
    this.listHeight.push(height);
   }
   // [0, 215, 1343, 2425, 3483, 4330, 5823, 7237, 8022, 8788, 9443]
  },
  selectMenu(index) {
   // console.log(index);

   let foodlist = this.$refs.foodScroll.getElementsByClassName(
    "food-list-hook"
   );

   // 根据下标，滚动到相对应的元素
   let el = foodlist[index];
   // 滚动到对应元素的位置
   this.foodScroll.scrollToElement(el, 100);
  },
  calculateCount(spus) {
    console.log(spus)
   let count = 0;
   spus.forEach(food => {
    if (food.count > 0) {
     count += food.count;
    }
   });

   return count;
  },
 }
};
</script>

calculateCount(spus) {
    console.log(spus)
   let count = 0;
   spus.forEach(food => {
    if (food.count > 0) {
     count += food.count;
    }
   });
   return count;
  },

<template>
 <div class="cartcontrol">
  <transition name="move">
   <div class="cart-decrease" @click="decreaseCart" v-show="food.count">
    <span class="inner icon-remove_circle_outline"></span>
   </div>
  </transition>
  <div class="cart-count" v-show="food.count">{{food.count}}</div>
  <div class="cart-add icon-add_circle" @click="increaseCart">
   <i class="bg"></i>
  </div>
 </div>
</template>

<script>
import Vue from 'vue'
export default {
 props:{
  food:{
   type:Object
  }
 },
 methods:{
  decreaseCart(){
   this.food.count--;//this指向了vue实例
    
  },
  increaseCart(){
   if(!this.food.count){
    Vue.set(this.food,'count',1);
   }else{
    this.food.count++;
   }
  }
  
 }
};
</script>

<template>
 <div class="shopcart" :class="{'highligh':totalCount>0}">
  <div class="shopcart-wrapper">
   <div class="content-left">
    <div class="logo-wrapper" :class="{'highligh':totalCount>0}">
     <span class="icon-shopping_cart logo" :class="{'highligh':totalCount>0}"></span>
     <i class="num" v-show="totalCount">{{totalCount}}</i>
    </div>
    <div class="desc-wrapper">
     <p class="total-price" v-show="totalPrice">￥{{totalPrice}}</p>
     <p class="tip" :class="{'highligh':totalCount>0}">另需{{shipping_fee_tip}}</p>
    </div>
   </div>

   <div class="content-right" :class="{'highligh':totalCount>0}">{{payStr}}</div>
  </div>
 </div>
</template>

<script>
// 导入BScroll
import BScroll from "better-scroll";

export default {
 props: {
  min_price_tip: {
   type: String,
   default: ""
  },
  shipping_fee_tip: {
   type: String,
   default: ""
  },
  selectFoods: {
   type: Array,
   default() {
    return [
     /* {
      min_price: 10,
      count: 3
     },
     {
      min_price: 7,
      count: 1
     } */
    ];
   }
  }
 },
 computed: {
  // 总个数
  totalCount() {
   let num = 0;
   this.selectFoods.forEach(food => {
    num += food.count;
   });

   return num;
  },
  // 总金额
  totalPrice() {
   let total = 0;
   this.selectFoods.forEach(food => {
    total += food.min_price * food.count;
   });

   return total;
  },
  // 结算按钮显示
  payStr() {
   if (this.totalCount > 0) {
    return "去结算";
   } else {
    return this.min_price_tip;
   }
  }
 },
 components: {
  BScroll
 }
};
</script>