js购物车用localhost存储

utils = {  
        setParam : function (name,value){  
            localStorage.setItem(name,value)  
        },  
        getParam : function(name){  
            return localStorage.getItem(name)  
        }  
    }  


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,"url": product.url, "num": product.num, "itime": product.itime,"sourceTable": product.sourceTable, "price": product.price,"number":product.number}], "totalNumber": product.num, "totalAmount": (product.price * 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].id == product.id) {  
                        //购物车中的项目不能重复，所以num被这只为1
                        //productlist[i].num = 1;  
                        productlist[i].num = parseInt(productlist[i].num) + parseInt(product.num);
                        result = true;  
                    }  
                }  
                if (!result) {  
                    //没有该商品就直接加进去  
                    productlist.push({ "id": product.id, "name": product.name,"url": product.url, "num": product.num, "itime": product.itime,"sourceTable": product.sourceTable, "price": product.price,"number":product.number });  
                }  
                //重新计算总价  
                jsonstr.totalNumber = parseInt(jsonstr.totalNumber) + parseInt(product.num);  
                jsonstr.totalAmount = parseFloat(jsonstr.totalAmount) + (parseInt(product.num) * parseFloat(product.price));  
                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].price)) - parseInt(productlist[i].num) * parseFloat(productlist[i].price));  
                    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");  
            var jsonstr = JSON.parse(ShoppingCart.substr(1, ShoppingCart.length));  
            var productlist = jsonstr.productlist;  
            orderdetail.totalNumber = jsonstr.totalNumber;  
            orderdetail.totalAmount = jsonstr.totalAmount;  
            return productlist;  
        },  
        //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].id == id) {  
                    jsonstr.totalNumber = parseInt(jsonstr.totalNumber) - parseInt(productlist[i].num);  
                    jsonstr.totalAmount = parseFloat(jsonstr.totalAmount) - parseInt(productlist[i].num) * parseFloat(productlist[i].price);  
                } else {  
                    list.push(productlist[i]);  
                }  
            }  
            jsonstr.productlist = list;  
            orderdetail.totalNumber = jsonstr.totalNumber;  
            orderdetail.totalAmount = jsonstr.totalAmount;  
            utils.setParam("ShoppingCart", "'" + JSON.stringify(jsonstr));  
        }  
    }