Html5 localStorage-based shopping cart JS script

I recently wrote a shopping cart JS script by referring to the Code on the Internet. It is very simple to directly write the code, shoppingCart. js: [javascript] utils = {setParam: function (name, value) {localStorage. setItem (name, value)}, getParam: function (name) {return localStorage. getItem (name) }}product = {id: 0, name: "", num: 0, price: 0.00, }; orderdetail = {username: "", phone: "", address: "", zipcode: "", totalNumber: 0, totalAmount: 0.00} cart = {// Add the product addproduct: function (pr Oduct) {var ShoppingCart = utils. getParam ("ShoppingCart"); if (ShoppingCart = null | ShoppingCart = "") {// Add product var jsonstr = {"productlist ": [{"id": product. id, "name": product. name, "num": product. num, "price": product. price}], "totalNumber": product. num, "totalAmount" :( product. price * product. num)}; utils. setParam ("ShoppingCart", "'" + JSON. stringify (jsonstr);} else {var jsonstr = JSON. parse (ShoppingCart. subst R (1, ShoppingCart. length); var productlist = jsonstr. productlist; var result = false; // you can check whether this item exists in the shopping cart. for (var I in productlist) {if (productlist [I]. id = product. id) {productlist [I]. num = parseInt (productlist [I]. num) + parseInt (product. num); result = true ;}} if (! Result) {// Add productlist directly without this product. push ({"id": product. id, "name": product. name, "num": product. num, "price": product. price});} // recalculates the total price of 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; // Save the shopping cart utils. setParam ("ShoppingCart", "'" + JSON. stringify (jsonstr) ;}}, // modify the number of purchased items 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 ;}}, // get all the items in the shopping cart 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;}, // determines whether there is existproduct: function (id) {var ShoppingCart = utils in the shopping cart. getParam ("ShoppingCart"); var jsonstr = JSON. parse (ShoppingCart. substr (1, ShoppingCart. length); var productlist = jsonstr. productlist; var result = false; for (var I in productlist) {if (productlist [I]. id = product. id) {result = true ;}} return result ;}, // Delete the eproduct: function (id) {var ShoppingCart = utils in the shopping cart. 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) ;}}; It is also easy to use: [javascript] var product = {'id': id, // attribute names are enclosed in quotation marks, the attributes are separated by commas (,): 'name': 'hhh ', 'num': jq (' # text-4 '). val (), 'price': 199.9}; // Add the item to the cart of the shopping cart. addproduct (product); var productlist = cart. getproductlist (); // retrieve the cart item alert ('', 'item: '+ productlist [0]. id + ''+ productlist [0]. name + ''+ productlist [0]. num + ''+ productlist [0]. price, 'confirmed ');