localstorage 实现购物车

utils = {
    setParam : function (name,value){
        var uid = $('#uid').val();
        name = name + '_' + uid;
        //console.log("set_" + name);
        localStorage.setItem(name,value);
    },
    getParam : function(name){
        var uid = $('#uid').val();
        name = name + '_' + uid;
        //console.log("get_" + name);
        return localStorage.getItem(name);
    }
};

product={
    id:0,
    name:"",
    num:0,
    vipprice:0.00,
    saleprice:0.00,
    imgurl:""
};
orderdetail={
    username:"",
    phone:"",
    address:"",
    zipcode:"",
    totalNumber:0,
    totalAmount:0.00
};
cart = {
    //向购物车中添加商品
    addproduct: function (product) {
        var ShoppingCart = utils.getParam("ShoppingCart");
        if (ShoppingCart == null || ShoppingCart == "") {
            //第一次加入商品
            var jsonstr = { "productlist": [{ "id": product.id, "name": product.name, "imgurl":product.imgurl, "num": product.num, "vipprice": product.vipprice, "saleprice": product.saleprice}], "totalNumber": product.num, "totalAmount": (product.vipprice * product.num) };
            utils.setParam("ShoppingCart", "'" + JSON.stringify(jsonstr));
        } else {
            var jsonstr = JSON.parse(ShoppingCart.substr(1, ShoppingCart.length));
            var productlist = jsonstr.productlist;
            var result = false;
            //查找购物车中是否有该商品
            for (var i in productlist) {
                if (productlist[i] != null){
                    if (productlist[i].id == product.id) {
                        productlist[i].num = parseInt(productlist[i].num) + parseInt(product.num);
                        result = true;
                    }
                }
            }
            //没有该商品就直接加进去
            if (!result) {
                productlist.push({ "id": product.id, "name": product.name,"imgurl": product.imgurl, "num": product.num, "vipprice": product.vipprice, "saleprice": product.saleprice });
            }
            //重新计算总价
            jsonstr.totalNumber = parseInt(jsonstr.totalNumber) + parseInt(product.num);
            jsonstr.totalAmount = parseFloat(jsonstr.totalAmount) + (parseInt(product.num) * parseFloat(product.vipprice));
            orderdetail.totalNumber = jsonstr.totalNumber;
            orderdetail.totalAmount = jsonstr.totalAmount;
            //保存购物车
            utils.setParam("ShoppingCart", "'" + JSON.stringify(jsonstr));
        }
    },
    //修改购买商品数量
    updateproductnum: function (id, num) {
        var ShoppingCart = utils.getParam("ShoppingCart");
        var jsonstr = JSON.parse(ShoppingCart.substr(1, ShoppingCart.length));
        var productlist = jsonstr.productlist;

        for (var i in productlist) {
            if (productlist[i].id == id) {
                jsonstr.totalNumber = parseInt(jsonstr.totalNumber) + (parseInt(num) - parseInt(productlist[i].num));
                jsonstr.totalAmount = parseFloat(jsonstr.totalAmount) + ((parseInt(num) * parseFloat(productlist[i].vipprice)) - parseInt(productlist[i].num) * parseFloat(productlist[i].vipprice));
                productlist[i].num = parseInt(num);
                orderdetail.totalNumber = jsonstr.totalNumber;
                orderdetail.totalAmount = jsonstr.totalAmount;
                utils.setParam("ShoppingCart", "'" + JSON.stringify(jsonstr));
                return;
            }
        }
    },
    //获取购物车中的所有商品
    getproductlist: function () {
        var ShoppingCart = utils.getParam("ShoppingCart");
        console.log(ShoppingCart);
        if(ShoppingCart){
            var jsonstr = JSON.parse(ShoppingCart.substr(1, ShoppingCart.length));//如果购物车没有商品会报错;??????但照样可以用;
            var productlist = jsonstr.productlist;
            orderdetail.totalNumber = jsonstr.totalNumber;
            orderdetail.totalAmount = jsonstr.totalAmount;
            return productlist;
        }else{
            return;
        }
    },
    //判断购物车中是否存在商品
    existproduct: function (id) {
        var result = false;
        var ShoppingCart = utils.getParam("ShoppingCart");
        if (ShoppingCart != null) {
            var jsonstr = JSON.parse(ShoppingCart.substr(1, ShoppingCart.length));
            var productlist = jsonstr.productlist;
            for (var i in productlist) {
                if (productlist[i].id == id) {
                    result = true;
                }
            }
        }
        return result;
    },
    //删除购物车中商品
    deleteproduct: function (id) {
        var ShoppingCart = utils.getParam("ShoppingCart");
        var jsonstr = JSON.parse(ShoppingCart.substr(1, ShoppingCart.length));
        var productlist = jsonstr.productlist;
        var list = [];
        for (var i in productlist) {
            if (productlist[i]){
                if (productlist[i].id == id) {
                    jsonstr.totalNumber = parseInt(jsonstr.totalNumber) - parseInt(productlist[i].num);
                    jsonstr.totalAmount = parseFloat(jsonstr.totalAmount) - parseInt(productlist[i].num) * parseFloat(productlist[i].vipprice);
                } else {
                    if(productlist[i].id){
                        list.push(productlist[i]);
                    }
                }
            }
        }
        jsonstr.productlist = list;
        orderdetail.totalNumber = jsonstr.totalNumber;
        orderdetail.totalAmount = jsonstr.totalAmount;
        utils.setParam("ShoppingCart", "'" + JSON.stringify(jsonstr));
    },
    //获取购物车中商品数量
    getproducttotalnum: function () {
        var ShoppingCart = utils.getParam("ShoppingCart");
        if (ShoppingCart){
            var jsonstr = JSON.parse(ShoppingCart.substr(1, ShoppingCart.length));
            var productlist = jsonstr.productlist;
            return jsonstr.totalNumber;
        }else{
            return 0;
        }
    },
    //获取购物车中商品总价
    getproducttotalAmount: function () {
        var ShoppingCart = utils.getParam("ShoppingCart");
        if (ShoppingCart){
            var jsonstr = JSON.parse(ShoppingCart.substr(1, ShoppingCart.length));
            // var productlist = jsonstr.productlist;
            return jsonstr.totalAmount;
        }else{
            return 0;
        }
    },


    //清除购物车某商品
    clearshoppingcar: function (){
        localStorage.clear();
    }
};




调用方法：cart.clearshoppingcar();　　//备注：在ajax中也可以执行该方法； 但在shoppingcar.js  中却不好封装ajax方法；