微信小程序购物车产品计价：
问题：当选中商品，价格累加时会出现无限循环小数
解答：在计算前先parseFloat(变量)，再计算的最后使用(变量).toFixed(2)保留两位小数
例如：
jiaCart:function(e){
var pid = e.currentTarget.id;
var pic = parseFloat(e.currentTarget.dataset.pic);
var cartList=this.data.cartList;
var ex = false;
for(var i=0;i<cartList.length;i++){
if(cartList[i].pid==pid){
cartList[i].num++;
ex = true;
}
}
if(!ex){
this.data.cartList.push({ pid: pid, num: 1 });
}
var cartPics = (this.data.cartPic+pic).toFixed(2);
this.setData({
cartPic:parseFloat(cartPics),
cartNum:this.data.cartNum+1,
cartList:cartList
});
},
jianCart:function(e){
var pid = e.currentTarget.id;
var pic = parseFloat(e.currentTarget.dataset.pic);
var cartList=this.data.cartList;
for(var i=0;i<cartList.length;i++){
if(cartList[i].pid==pid){
cartList[i].num--;
if(cartList[i].num<=0){
cartList.splice(i,1);
}
}
}
var showCart=this.data.cartNum;
if(showCart==1 && (this.data.cartNum-1)<=0){
this.setData({
showCart:0
});
}
var cartPics = (this.data.cartPic-pic).toFixed(2);
this.setData({
cartPic:parseFloat(cartPics),
cartNum:this.data.cartNum-1,
cartList:cartList
});
}