微信小程序如何实现简单购物车小功能

本篇内容介绍了“微信小程序如何实现简单购物车小功能”的有关知识，在实际案例的操作过程中，不少人都会遇到这样的困境，接下来就让小编带领大家学习一下如何处理这些情况吧！希望大家仔细阅读，能够学有所成！

1.应用场景

适用于商城、秒杀、商品购买等类型的小程序，负责将顾客浏览的商品保存下来，方便客户集中比较商品与购买商品。

2.思路分析

实现购物车功能前请思考以下问题：

1.小程序如何布局？使用什么布局能提升页面开发效率？？

2.将购物车功能分为四个小功能：(1)一键全选/取消商品 （2）动态添加商品可手动输入 （3）计算结算商品金额 （4）左滑动删除商品

答：（1）在小程序中主要是兼容安卓与ios两种型号手机，在页面开发中可使用flex布局，能极大的提高页面的开发效率。（2）请仔细阅读代码分析，看懂自己也可轻松实现购物车功能 so easy！！！

3.代码分析

1. 一键全选/取消

allSelect: function (e) {
    var that = this
    var allSelect = e.currentTarget.dataset.select//判断是否选中 circle是 success否
    var newList = that.data.slideProductList
    if (allSelect == "circle") {
      for (var i = 0; i < newList.length; i++) {
        newList[i].select = "success"
      }
      var select = "success"
    } else {
      for (var i = 0; i < newList.length; i++) {
        newList[i].select = "circle"
      }
      var select = "circle"
    }
    that.setData({
      slideProductList: newList,
      allSelect: select
    })
    that.countNum()//计算商品数量
    that.count()//计算商品金额
  },

2. 动态添加商品可手动输入

a 添加商品

addtion: function (e) {//添加商品
    var that = this
    var index = e.currentTarget.dataset.index
    var num = e.currentTarget.dataset.num
    if (num < 99) { //默认峰值99件
      num++
    }
    var newList = that.data.slideProductList
    newList[index].num = num
    that.setData({
      goodsNum:num,
      slideProductList: newList
    })
    that.countNum()
    that.count()
  },

b 减少商品

subtraction: function (e) {//减少商品
    var that = this
    var index = e.currentTarget.dataset.index
    var num = e.currentTarget.dataset.num
    var newList = that.data.slideProductList
    //当1件时，再次点击移除该商品
    if (num == 1) {
      newList.splice(index, 1)
    } else {
      num--
      newList[index].num = num
    }
    that.setData({
      goodsNum: num,
      slideProductList: newList
    })
    that.countNum()
    that.count()
  },

c 直接输入

inputNum:function(e){
    var num = e.detail.value;
    this.setData({goodsNum:num})
  },
  numIputBlur:function(e){
    var that = this;
    var num = that.data.goodsNum;
    var index = e.currentTarget.dataset.index;
    var newList = that.data.slideProductList
    if (num == "") { //判空
      newList[index].num = 1;
      that.setData({
        slideProductList: newList
      })
    }else if (num < 1) {
      that.setData({
        goodsNum: newList[index].num,
        slideProductList: newList
      })
      wx.showToast({
        title: '亲，该宝贝不能减少了哦~',
        icon: 'none'
      })
    }else if(num>99){
      that.setData({
        goodsNum: newList[index].num,
        slideProductList: newList
      })
      wx.showToast({
        title: '亲，该宝贝最多购买99件哦~',
        icon: 'none'
      })
    }else{
      newList[index].num = num;
      that.setData({
        slideProductList: newList
      })
    }
    that.countNum()
    that.count()
  },

3. 计算结算商品金额

count: function () {//计算金额方法
    var that = this
    var newList = that.data.slideProductList
    var newCount = 0
    for (var i = 0; i < newList.length; i++) {
      if (newList[i].select == "success") {
        newCount += newList[i].num * newList[i].price
      }
    }
    that.setData({
      count: newCount
    })
  },

4. 页面左滑动删除商品

功能后续整理

4. 具体实现代码

1.wxml 

<view class="product-container">
    <view class="product-list" style='height:{{height}}px'>
        <view class="product-item" wx:for="{{slideProductList}}" wx:for-index="index" wx:key='slideProductList'>
            <slide-delete pid="{{item.id}}" bindaction="handleSlideDelete" wx:key='slideProductList'>
                <view class="product-item-wrap">
                    <icon type="{{item.select}}" size="19" data-index="{{index}}" data-select="{{item.select}}" bindtap="change" color="red" />
                    <view class="product_img">
                        <image src="{{item.url}}" class='goods-img' mode="widthFix"></image>
                    </view>
                    <view class="product-movable-item">
                        <view class="goods-name">{{item.name}}</view>
                        <view class="goods-type">最新款
                            <text>{{item.style}}</text>
                        </view>
                        <view class="goods-price">￥{{item.price}}</view>
                    </view>
                    <view class="product-movable-item product-movable-item-amount">
                        <view class="num-box">
                            <view class="btn-groups">
                                <button class="goods-btn btn-minus" data-index="{{index}}" data-num="{{item.num}}" bindtap="subtraction">—</button>
                                <input class='num' type='number' data-index="{{index}}" bindblur="numIputBlur" bindinput='inputNum' value='{{item.num}}'></input>
                                <button class="goods-btn btn-add" data-index="{{index}}" data-num="{{item.num}}" bindtap="addtion">+</button>
                            </view>
                        </view>
                    </view>
                </view>
            </slide-delete>
        </view>
    </view>
    <view class="cart-fixbar">
        <view class="allSelect">
            <icon type="{{allSelect}}" size="19" data-select="{{allSelect}}" bindtap="allSelect" color='#fff' />
            <view class="allSelect-text">全选</view>
        </view>
        <view class="count">
            <text>合计：</text>￥{{count}}
        </view>
        <view class="order">
            <view class="orders">
                去结算
                <text class="allnum">({{num}})</text>
            </view>

        </view>
    </view>
</view>
<view class="footer">
    <navigator class="ft_item" url="../shoping/shoping" hover-class="none" open-type='redirect'>
        <image src="../../image/sy_1.png"></image>
        <view class="item_title">首页</view>
    </navigator>
    <navigator url="../classification/classification" hover-class="none" open-type='redirect' class="ft_item">
        <image src="../../image/fl_1.png"></image>
        <view class="item_title">分类</view>
    </navigator>
    <view class="ft_item">
        <image src="../../image/gwc.png"></image>
        <view class="item_title">购物车</view>
    </view>
    <navigator hover-class="none" url="../my/my" open-type='redirect' class="ft_item">
        <image src="../../image/gr_1.png"></image>
        <view class="item_title">我的</view>
    </navigator>
</view>

2.js

const app = getApp()
Page({

  /**
   * 页面的初始数据
   */
  data: {
    goodsNum:'',
    userInfo: {},
    hasUserInfo: false,
    canIUse: wx.canIUse('button.open-type.getUserInfo'),

    slideProductList: [
      {
        id:1,
        name: '智能手环1111111112222211',
        url: "../../image/bracelet.jpg",
        style: "2代",
        price: "149.5",
        select: "circle",
        num: "1",
        code: "0001",
        amount: 500
      },
      {
        id: 2,
        name: "指环支架",
        url: "../../image/ring.jpg",
        style: "金色",
        price: "19.9",
        select: "circle",
        code: "0002",
        num: "1",
        amount: 500
      },
      {
        id: 3,
        name: "新款平板电脑",
        url: "../../image/iphone.png",
        style: "9.7英寸",
        price: "100",
        select: "circle",
        code: "0003",
        num: "1",
        amount: 110
      },
      {
        id: 4,
        code: "0001",
        name: "无人机",
        url: "../../image/uav.jpg",
        style: "低配版",
        price: "4999",
        select: "circle",
        code: "0004",
        num: "1",
        amount: 200
      },
      {
        id: 5,
        code: "0001",
        name: "无人机",
        url: "../../image/uav.jpg",
        style: "低配版",
        price: "4999",
        select: "circle",
        code: "0004",
        num: "1",
        amount: 200
      },
      {
        id: 6,
        code: "0001",
        name: "无人机",
        url: "../../image/uav.jpg",
        style: "低配版",
        price: "4999",
        select: "circle",
        code: "0004",
        num: "1",
        amount: 200
      },
    ],
    allSelect: "circle",
    num: 0,
    count: 0,
    lastX: 0,
    lastY: 0,
    text: "没有滑动",

   
  },

  change: function (e) {
    var that = this
    var index = e.currentTarget.dataset.index
    var select = e.currentTarget.dataset.select

    if (select == "circle") {
      var stype = "success"
    } else {
      var stype = "circle"
    }
    var newList = that.data.slideProductList
    newList[index].select = stype
    that.setData({
      slideProductList: newList
    })
    that.countNum()
    that.count()
  },
  addtion: function (e) {
    var that = this
    var index = e.currentTarget.dataset.index
    var num = e.currentTarget.dataset.num
    //默认99件
    if (num < 99) {
      num++
    }
    var newList = that.data.slideProductList
    newList[index].num = num
    that.setData({
      goodsNum:num,
      slideProductList: newList
    })
    that.countNum()
    that.count()
  },
  inputNum:function(e){
    var num = e.detail.value;
    this.setData({
      goodsNum:num
    })
  },
  numIputBlur:function(e){
    var that = this
    var num = that.data.goodsNum
    var index = e.currentTarget.dataset.index
    var newList = that.data.slideProductList
    if (num == "") { //盘空
      newList[index].num = 1;
      that.setData({
        slideProductList: newList
      })
    }else if (num < 1) {
      that.setData({
        goodsNum: newList[index].num,
        slideProductList: newList
      })
      wx.showToast({
        title: '亲，该宝贝不能减少了哦~',
        icon: 'none'
      })
    }else if(num>99){
      
      that.setData({
        goodsNum: newList[index].num,
        slideProductList: newList
      })
      wx.showToast({
        title: '亲，该宝贝最多购买99件哦~',
        icon: 'none'
      })
    }else{
      newList[index].num = num;
      that.setData({
        slideProductList: newList
      })
    }
    that.countNum()
    that.count()
  },
  //减法
  subtraction: function (e) {
    var that = this
    var index = e.currentTarget.dataset.index
    var num = e.currentTarget.dataset.num
    var newList = that.data.slideProductList
    
    if (num == 1) {//当数量为1件时，再次点击移除该商品
      newList.splice(index, 1)
    } else {
      num--
      newList[index].num = num
    }
    that.setData({
      goodsNum: num,
      slideProductList: newList
    })
    that.countNum()
    that.count()
  },
  //全选
  allSelect: function (e) {
    var that = this
    var allSelect = e.currentTarget.dataset.select //先判断是否选中
    var newList = that.data.slideProductList
    console.log(newList)
    if (allSelect == "circle") {
      for (var i = 0; i < newList.length; i++) {
        newList[i].select = "success"
      }
      var select = "success"
    } else {
      for (var i = 0; i < newList.length; i++) {
        newList[i].select = "circle"
      }
      var select = "circle"
    }
    that.setData({
      slideProductList: newList,
      allSelect: select
    })
    that.countNum()
    that.count()
  },
 
  countNum: function () { //计算数量
    var that = this
    var newList = that.data.slideProductList
    var allNum = 0
    for (var i = 0; i < newList.length; i++) {
      if (newList[i].select == "success") {
        allNum += parseInt(newList[i].num)
      }
    }
    parseInt
    that.setData({
      num: allNum
    })
  },
  
  count: function () {//计算金额方法
    var that = this
    var newList = that.data.slideProductList
    var newCount = 0
    for (var i = 0; i < newList.length; i++) {
      if (newList[i].select == "success") {
        newCount += newList[i].num * newList[i].price
      }
    }
    that.setData({
      count: newCount
    })
  },

  

  /**
   * 生命周期函数--监听页面加载
   */
  onLoad: function (options) {
    var width=wx.getSystemInfoSync().windowWidth
    var height=wx.getSystemInfoSync().windowHeight
    height=height-55-53;
    this.setData({
      height:height
    })
  },

  /**
   * 生命周期函数--监听页面初次渲染完成
   */
  onReady: function () {

  },

  /**
   * 生命周期函数--监听页面显示
   */
  onShow: function () {

  },

  /**
   * 生命周期函数--监听页面隐藏
   */
  onHide: function () {

  },

  /**
   * 生命周期函数--监听页面卸载
   */
  onUnload: function () {

  },

  /**
   * 页面相关事件处理函数--监听用户下拉动作
   */
  onPullDownRefresh: function () {

  },

  /**
   * 页面上拉触底事件的处理函数
   */
  onReachBottom: function () {

  },

  /**
   * 用户点击右上角分享
   */
  onShareAppMessage: function () {

  }
})

3.wxss

.cart-box .item {display:flex;flex-direction:row;align-items:center;padding:20rpx;border-top:8rpx solid #f0f3fa;}
.cart-box .item .goods-info {margin-left:20rpx;}
.goods-img {width:160rpx;margin-left:20rpx;height:160rpx;}
.cart-box .row {color:#fff;display:flex;flex-direction:row;width:430rpx;justify-content:space-between;margin-bottom:10rpx;}
.goods-name {font-size:32rpx;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;color:#333;padding-bottom:10rpx;width:290rpx;}
.goods-price {font-size:32rpx;color:#e02e24;position:relative;top:14rpx;}
.goods-type {color:#999;font-size:24rpx;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;width:240rpx;padding-bottom:10rpx;}
.num-box {display:flex;flex-direction:row;justify-content:flex-end;position:relative;top:6rpx;}
.goods-btn {width:44rpx;height:44rpx;padding:0;line-height:40rpx;font-weight:400;color:#fff;margin:0;background:#e60a30;border-radius:50%;}
.num {color:#999;width:50rpx;margin-left:5rpx;margin-right:5rpx;text-align:center;line-height:50rpx;font-size:30rpx;}
.btn-add {font-size:36rpx;}
.btn-minus {font-size:18rpx;background:#f8babb;}
.btn-groups {display:flex;flex-direction:row;justify-content:flex-end;background:#f4f4f4;padding:2rpx;border-radius:10rpx;}
.cart-fixbar {position:fixed;bottom:113rpx;background:#e60a30;height:106rpx;width:95%;margin:0 20rpx;display:flex;flex-direction:row;align-items:center;border-top-left-radius:20rpx;border-top-right-radius:20rpx;}
.cart-box .item:last-child {border-bottom:8rpx solid #f0f3fa;}
.cart-fixbar .allSelect {display:flex;flex-direction:row;height:106rpx;align-items:center;color:#fff;font-size:32rpx;margin-left:20rpx;}
.cart-fixbar .allSelect-text {margin-left:16rpx;font-size:28rpx;}
.cart-fixbar .count {color:#fff;font-size:36rpx;position:absolute;right:220rpx;display:flex;align-items:center;}
.cart-fixbar .count text {font-size:28rpx;}
.cart-fixbar .order {color:#e02e24;height:58rpx;background:#fff;line-height:58rpx;position:absolute;right:0;margin:0 20rpx;font-size:28rpx;border-radius:10rpx;}
.cart-fixbar .orders {padding:0 18rpx;}
.cart-fixbar .allnum {font-size:28rpx;}
.row_boxs {display:flex;align-items:center;}
.goods-type {flex:1;}
.goods-type text {padding-right:10rpx;}
.section {padding-bottom:220rpx;}
.footer {border-top:1rpx solid #eee;position:fixed;bottom:0;width:100%;display:flex;background:#fff;font-size:24rpx;height:55px;align-items:center;}
.footer .ft_item {width:25%;text-align:center;}
.footer .ft_item image {width:44rpx;height:44rpx;margin-top:10rpx;}
.footer .ft_item:nth-child(3) .item_title {color:#e60a30;}
.section_img {width:110rpx;height:110rpx;}
.section_boxs {text-align:center;margin:50% auto 0;}
.cart-box_p,.section_p {text-align:center;font-size:26rpx;padding-top:10rpx;color:#999;}
.cart-box_p {padding-top:60rpx;}
.cart-box_p text {border:1rpx solid #eee;padding:10rpx 24rpx;letter-spacing:1rpx;}
.title {margin:60rpx 0 30rpx;font-size:40rpx;text-align:center;font-weight:bold;color:#383a3d;}
.product-list .product-item {position:relative;width:100vw;border-bottom:10rpx solid #f0f3fa;box-sizing:border-box;background:#fff;z-index:999;}
.slide-product-list .slide-product-item {position:relative;width:100vw;border-bottom:2rpx solid #e9e9e9;box-sizing:border-box;background:#fff;z-index:999;}
.product-list .product-item movable-area {height:120rpx;width:calc(100vw - 120rpx);}
.product-list .product-item movable-view {height:120rpx;width:100vw;background:#fff;z-index:999;}
.product-list .product-item:first-child {border-top:10rpx solid #f0f3fa;}
.product-list .product-item .delete-btn {position:absolute;top:0;bottom:0;right:0;width:120rpx;font-family:PingFangSC-Regular;font-size:24rpx;color:#fff;line-height:120rpx;z-index:1;background:#e66671;text-align:center;}
.product-list .product-item-wrap {position:relative;display:flex;align-items:center;padding:8rpx 0 20rpx 20rpx;box-sizing:border-box;}
.product-list .product-item-wrap .product-movable-item {flex:1;/* overflow:hidden;*/}
.product-list .product-item-wrap .product-movable-item-name {font-family:PingFangSC-Regular;font-size:28rpx;color:#71747a;line-height:60rpx;margin-right:10rpx;overflow:hidden;white-space:nowrap;text-overflow:ellipsis;}
.product-list .product-item-wrap .product-movable-item-code {font-family:PingFangSC-Regular;font-size:24rpx;color:#969aa3;}
.product-list .product-item-wrap .product-movable-item-amount {flex:1;padding-right:50rpx;position:relative;}
.product-list .product-item-wrap .product-movable-item-amount .amount {width:120rpx;font-size:28rpx;color:#383a3d;line-height:60rpx;}
.product-list .product-item-wrap .product-movable-item-amount .unit {position:absolute;top:0;right:30rpx;font-size:28rpx;color:#969aa3;line-height:60rpx;}
.product_img {display:flex;align-items:center;padding-right:20rpx;}
.product-list {display:block;overflow-y:auto;}

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