最近在做一个微信小程序商城在实现购物车功能时费了一点时间，在此分享出来给大家哈

github地址：

https://github.com/yangyuscript/shopcar-wechat-.git

效果图：

最重要的js代码：

var app=getApp()
Page({
    data: {
        userInfo: {},
        selectAll:true,
        totalsum:0,
        totalnum:0,
        loadingHidden: false
    },
    //事件处理函数
    bindMinus:function(e){
        var $index=parseInt(e.currentTarget.dataset.index);
        var num=this.data.userShopcarSocks[$index].num;
        if(num>0){
            num--;
        }
        var minsStatus=num<=0?true:false;
        var minusStatuses=this.data.minusStatuses;
        minusStatuses[$index]=minsStatus;
        var userShopcarSocks = this.data.userShopcarSocks;
        userShopcarSocks[$index].num = num;
        this.setData({
            userShopcarSocks:userShopcarSocks,
            minusStatuses:minusStatuses
        })
        if(this.data.userShopcarSocks[$index].selected){
            this.getTotal();
        }
    },
    bindPlus:function(e){
        var $index = parseInt(e.currentTarget.dataset.index);
        var num = this.data.userShopcarSocks[$index].num;
        num++;
        var minsStatus = num <= 0 ? true : false;
        var minusStatuses = this.data.minusStatuses;
        minusStatuses[$index] = minsStatus;
        var userShopcarSocks = this.data.userShopcarSocks;
        userShopcarSocks[$index].num = num;
        this.setData({
            userShopcarSocks: userShopcarSocks,
            minusStatuses:minusStatuses
        })
        if (this.data.userShopcarSocks[$index].selected) {
            this.getTotal();
        }
    },
    bindSelectOne:function(e){
        var $index=parseInt(e.currentTarget.dataset.index);
        var selected=this.data.userShopcarSocks[$index].selected;
        selected=!selected;
        var userShopcarSocks=this.data.userShopcarSocks;
        userShopcarSocks[$index].selected=selected;
        this.setData({
            userShopcarSocks:userShopcarSocks
        });
        this.getTotal();
    },
    bindSelectAllhah:function(){
        var $selectAll=this.data.selectAll;
        $selectAll=!$selectAll;
        var $userShopcarSocks=this.data.userShopcarSocks;
        if($selectAll){
            for (var i = 0, len = $userShopcarSocks.length; i < len; i++) {
                $userShopcarSocks[i].selected=true;
            }
        }else{
            for (var i = 0, len = $userShopcarSocks.length; i < len; i++) {
                $userShopcarSocks[i].selected = false;
            }
        }
        this.setData({
            selectAll: $selectAll,
            userShopcarSocks:$userShopcarSocks
        })
        this.getTotal();
    },
    bindbuynow:function(){
        var $buyShopcarSocks=[];
        var $userShopcarSocks=this.data.userShopcarSocks;
        var j=0;
        console.log("shopcar's length is "+$userShopcarSocks);
        for(var i=0,len=$userShopcarSocks.length;i<len;i++){
            if($userShopcarSocks[i].selected){
                $buyShopcarSocks[j++]=$userShopcarSocks[i];
            }
        }
        console.log("shopcar is "+$buyShopcarSocks);
        wx.setStorageSync("buyShopcarSocks",$buyShopcarSocks);
        wx.navigateTo({
            url:'../confirmorder/confirmorder?totalnum='+this.data.totalnum+'&totalsum='+this.data.totalsum+'&buyShopcarSocks='+$buyShopcarSocks
        });
    },
    getTotal:function(){
        //计算总价价格总件数  
        var $userShopcarSocks = this.data.userShopcarSocks;
        var $totalnum = 0;
        var $totalsum = 0;
        var $count = 0;
        var $selectAll = false;
        for (var i = 0, len = $userShopcarSocks.length; i < len; i++) {
            if ($userShopcarSocks[i].selected) {
                console.log("结算");
                $count++;
                $totalnum += $userShopcarSocks[i].num;
                $totalsum += parseFloat($userShopcarSocks[i].sock.price * $userShopcarSocks[i].num);
            }
        }
        if ($count == len) {
            $selectAll = true;
        }
        this.setData({
            totalnum: $totalnum,
            totalsum: $totalsum.toFixed(2),
            selectAll: $selectAll
        })
    },
    onLoad: function () {
        console.log('onLoad')
        var that = this
        var $openid=wx.getStorageSync("user").openid;
        //调用应用实例的方法获取全局数据
        app.getUserInfo(function (userInfo) {
            //更新数据
            that.setData({
                userInfo: userInfo
            })
        });
    },
    onShow:function(){
        //获取初始化数据  
        var $openid=wx.getStorageSync("user").openid;
        var that=this;
        wx.request({
        url: app.globalData.serverPath + 'wechat/findUserShopcarSocks?openid=' + $openid,
        data: {},
        method: 'GET', // OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, CONNECT
        // header: {}, // 设置请求的 header
        success: function (res) {
        // success
        console.log(res.data.userShopcarSocks);
        //修改合适数据  
        var minusStatuses=[];
        for (var i = 0, len = res.data.userShopcarSocks.length;i<len;i++){
            if (res.data.userShopcarSocks[i].sock.title.length>10){
                res.data.userShopcarSocks[i].sock.title = res.data.userShopcarSocks[i].sock.title.substring(0,9)+"...";
            }
            if (res.data.userShopcarSocks[i].selected=="true"){
                res.data.userShopcarSocks[i].selected=true;
            }else{
                res.data.userShopcarSocks[i].selected = false;
            }
            minusStatuses[i]=false;
        }
        that.setData({
            userShopcarSocks: res.data.userShopcarSocks,
            sockPicUrl: app.globalData.serverPath + "img/uploadSockImg/",
            minusStatuses:minusStatuses
        });
        that.getTotal();
        setTimeout(function () {
        that.setData({
            loadingHidden: true
        })
        }, 1500)
    },
    fail: function (res) {
        // fail
    },
    complete: function (res) {
    // complete
    }
});
 }
})

大家多看看源码哦，这样才会真的进步。。。加油！！！需要源码可以去github地址fork哈，当然请大牛们批评指正，再次感谢！！！