我正在开发一个程序，可让您将商品添加到购物车，更改购物车中某个商品的数量，并动态计算小计，税金，运费和总额。
现在我遇到的问题是我的所有计算总数都是0.
以下是我认为我最有可能出错的地方，我会在页面底部提供完整的代码。
//Used to dynamically change subtotal,tax,shipping, and total when quantity is adjusted
$("#selected-list").on('change', '.quantity', calculateTotalPrice);
function calculateTotalPrice(){
var subtotal = calculateSubtotal();
var tax = calculateTax();
var shipping = calculateShipping();
var total = calculateTotal();
$('#subtotal').html(subtotal.toFixed(2));
$('#tax').html(tax.toFixed(2));
$('#shipping').html(shipping.toFixed(2));
$('#total').html(total.toFixed(2));
}
function calculateSubtotal(){
var subtotal = 0;
var quantity = 1;
for(var i = 0; i < cart.lengh; i++){
quantity = parseInt($(this).val());
var productPrice = parseInt(item_list[cart[i]].price);
subtotal += parseInt(productPrice * quantity);
}
return subtotal;
}
function calculateTax(){
var taxAmount = 0;
var taxes = .06;
var subtotal = calculateSubtotal();
taxAmount = parseInt(subtotal * taxes);
return taxAmount;
}
function calculateShipping(){
var shippingAmount = 0;
var shippingPerc = .02;
var subtotal = calculateSubtotal();
shippingAmount = parseInt(subtotal * shippingPerc);
return shippingAmount;
}
function calculateTotal(){
var totalCost = 0;
var subtotal = calculateSubtotal();
var taxes = calculateTax();
var shippingCost = calculateShipping();
totalCost = parseInt(subtotal + taxes + shippingCost);
return totalCost;
}
我已经搞砸了一段时间了，有趣的是如果我以calculateSubtotal()这样的方式在我的for循环之后立即发出提醒：
alert(subtotal)
alert(item_list[cart[0]].price)
subtotal将始终打印为0，item_list[cart[0]].price将始终打印出购物车中商品的正确价格。这让我感到困惑，因为我将数量的默认值设为1，如果它的价格正确，那么它甚至不能等于0。
以下是我的其余代码：
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html>
<head>
<meta charset="utf-8">
<!-- Set the viewport so this responsive site displays correctly on mobile devices -->
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>UWW Semester Planner </title>
<!-- Include bootstrap CSS -->
<link rel="stylesheet" href="http://netdna.bootstrapcdn.com/bootstrap/3.1.0/css/bootstrap.min.css">
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"> </script>
<style type="text/css">
.courselist { cursor: pointer;}
.t-head { color: #fff; background-color: #333366; font-size: 20px; line- height: 20px; }
#top-box, #footer { background-color: #330066; color: #fff; text-align: center;}
#content {border: 1px solid #330099;}
</style>
<script>
$(function(){
/* The following function defines a constructor for creating an array of objects with four properties.
The keyword "this" refers to the instance of the object
*/
function Item(type,title,description,price){
this.type = type;
this.title = title;
this.description = description;
this.price = price;
}
//create an array to store items
var item_list = [];
var cart = []; //store index of elements in the shopping cart
//add items
//add baseballgear items
item_list.push(new Item('baseballgear','Louisville Slugger', 'The finest craftsmanship and finest materials ensure stepping to the plate with the Louisville Slugger® M9 Maple M110 Bat will allow you to swing what the pros swing.', 79.99 ));
item_list.push(new Item('baseballgear','Marucci Bat', 'Named for one of the most lethal hitters in the game, the Marucci® CUTCH22 Pro Model Baseball Bat features the same cut and finish swung by MLB® center fielder, Andrew McCutchen. The "Cutch" features a large, powerful, balanced barrel with a sleek cherry red and grey finish to deliver maximum performance at the plate. This adult wooden bat is also handcrafted and bone-rubbed to ensure superior quality and surface hardness.', 139.99));
item_list.push(new Item('baseballgear', 'Rawlings Glove', "Unrivaled quality season after season, the Rawlings® 11.25'' Pro Preferred® Series Glove returns to provide elite craftsmanship and superior performance for elite middle infielders.",349.99));
item_list.push(new Item('baseballgear', 'Wilson Glove', "Enhance your field performance with unrivaled dependability with the Wilson® 11.5 A2000™ Series Glove. Made with Pro Stock® leather for long-lasting performance, this glove's construction is preferred by professionals for its top-notch quality. Dri-Lex® technology in the wrist lining transfers moisture away from the skin to keep you cool and dry. The advanced design has been improved upon by the Wilson&Reg; Advisory Staff.",249.99 ));
item_list.push(new Item('baseballgear', 'Easton Baseball Helmet', 'Give your favorite player maximum protection at the plate with the Easton® Junior Z5 Elite Baseball Helmet. The ABS shell withstands impact and disperses energy away from the head, with a stylish Digi-Camo design. Featuring dual density foam liner for advanced comfort, this helmet boasts BioDri™ padded inner liner to wick moisture away from the skin to keep them cool and dry. Wrapped ear pads provide enhanced coverage around the head.', 54.99));
item_list.push(new Item('baseballgear', 'Rawlings Batting Gloves', 'Get the most out of your batting gloves this season with the Rawlings® Adult Workhorse 950 Batting Gloves. These gloves feature an Oiltac® leather palm pad to provide better grip and softness. Equipped with a Dura-Plus™ pad for added protection in the palm, the Dynamic Fit System™ provides greater comfort, flex, and feel during every play. The adjustable wrist closure is reinforced to provide a more secure fit', 34.99));
//add soccergear items
item_list.push(new Item('soccergear', 'Nike Ordem Soccer Ball', 'Hit the back of the net with the The Nike® Ordem 3 PL Soccer Ball. The Ordem 3 is the official match ball of the English Premier League for the 2015-2016 season. This FIFA® approved ball features Aerowtrac grooves and a micro-textured casing for accurate flight. The carbon latex bladder and fuse-welded construction allow for an exceptional touch while the vivid visual Power Graphics allow you to track the ball so you can react quickly.', 150.00));
item_list.push(new Item('soccergear', 'Wilson Shinguard', 'Maximize your protection for practice or game day with the Wilson® NCAA® Forte ll Soccer Shinguard. This high impact shinguard is constructed of a removable inner shell for adjustable protection to diffuse impact during elite-level play. Its Lycra® sleeve contains power band enhancements for added compression and blood circulation. Focus on your game with the Wilson® NCAA® Forte ll Soccer Shinguard.', 24.99 ));
item_list.push(new Item('soccergear', 'Adidas Goalie Gloves', 'Protect the goal line with intensity when you sport the adidas® Ace Zones Pro Soccer Goalie Gloves. Evo Zone Technology delivers superior catching and control so you can dominate the game from the net. The negative cut ensures a snug feel while seamless touch features deliver breathability through the latex and foam construction. A stretch-strap wraps your hand to complete the gloves with a comfortable fit.', 114.99));
item_list.push(new Item('soccergear', 'Storelli Exoshield Goalie Jersey', 'Block kicks to the net with maximum mobility in the Storelli® Exoshield GK Adult Goalie Gladiator Jersey. This jersey withstands impact between the posts with polyurethane foam protection at the elbows. For increased comfort, the compression material wicks moisture away to keep the skin cool and dry. Dive and defend without distraction in the lightweight Storelli® Exoshield GK Adult Goalie Gladiator Jersey.', 64.99));
item_list.push(new Item('soccergear', 'Storelli BodyShield Slider Shorts', "Enjoy superior protection with the classic fit of the Storelli® sliders. Lightweight foam padding delivers high-performance protection to keep you safe from impact, swelling and cuts, while the unique design lets you freely move while the pads stay in place. Stay safe on the field with the antimicrobial technology and lightweight padding of the Storelli® Men's Slider Shorts.", 59.99));
item_list.push(new Item('soccergear', 'Adidas Estadio Teamp Backpack', 'Transport your gear to and from the field in style with the adidas® Estadio Team Backpack II. Built with soccer in mind, this backpack is constructed with multiple compartments to conveniently organize and store all of your gear. LoadSpring™ technology adds comfort to the shoulder straps so you can carry more equipment. FreshPAK™ shoe compartment keeps gear fresh throughout the season.', 55.00));
//add videogames
item_list.push(new Item('videogames', 'Star Wars Battlefront', 'Visit classic planets from the original Star Wars™ trilogy, detailed with an unprecedented amount of realism and sense of authenticity that will transport you to a galaxy far, far away', 59.99));
item_list.push(new Item('videogames', 'Just Cause 3', "The Mediterranean republic of Medici is suffering under the brutal control of General Di Ravello, a dictator with an insatiable appetite for power. Enter Rico Rodriguez, a man on a mission to destroy the general's ambitions by any means necessary. With more than 400 square miles of complete freedom from sky to seabed, and a huge arsenal of weaponry, gadgets and vehicles, prepare to unleash chaos in the most creative and explosive ways you can imagine.", 59.99));
item_list.push(new Item('videogames', 'Call of Duty Black Ops III', 'Call of Duty: black Ops III is the ultimate 3-games-in-1 experience. The Campaign you must navigate the hot spots of a new Cold War to find your missing brothers. Multiplayer features a new momentum-based chained movement system, allowing players to fluidly move through the environment with finesse. No Treyarch title would be complete without its signature Zombies offering "Shadows of Evil" has its own distinct storyline right out of the box.', 59.99));
item_list.push(new Item('videogames', 'Fallout 4', 'The epic storylines, adrenaline-pumping action and explosive thrills are back. The Fallout franchise returns with Fallout 4. Grab your controller and get ready to dive back into the enveloping storyline of this legendary series.', 59.99));
item_list.push(new Item('videogames', 'Halo 5: Guardians', 'A mysterious and unstoppable force threatens the galaxy, the Master Chief is missing and his loyalty questioned. Experience the most dramatic Halo story to date in a 4-player cooperative epic that spans three worlds. Challenge friends and rivals in new multiplayer modes: Warzone, massive 24-player battles, and Arena, pure 4-vs-4 competitive combat.*', 59.99));
item_list.push(new Item('videogames', "Assassin's Creed Syndicate", "WELCOME TO THE FAMILY — London, 1868. The Industrial Revolution fattens the purses of the privileged while the working class struggles to survive — until two Assassins rise to lead the world's first organized crime family. Conquer the streets of London. Bring the ruling class to their knees. Make history in a visceral adventure unlike any game you've played before.", 59.99));
// display item list
displayAll();
$('#category').on('change', function(){
// read the selected category using 'value' attribute
var category = $(this).val();
if (category == '0')
displayAll(); // display all items
else
displaySelectedItems(category); // display selected items
// Check all the selected items in the cart
checkCartElements();
});
function checkCartElements(){
$('.addme').each(function(){ // do something with each checkbox
// read its index
var index = $(this).data('index');
// check if the item with a selected index is in the cart
var check = inCart(index); // returns true/false
if(check == true){
$(this).prop('checked', true);
} else {
$(this).prop('checked', false);
}
});
}
function inCart(index){
for (var i=0; i<cart.length; i++){
if (cart[i] == index)
return true;
}
return false;
}
function displaySelectedItems(category){
var itemInfo = '';
/* display data:
use a for loop to go through each element in the item_list array
*/
for (var i=0; i<item_list.length; i++){
// display only selected items
if (item_list[i].type == category){
itemInfo += createItemData(item_list[i], i);
}
// add each item to the table
$('#item-list').html(itemInfo);
}
}
function displayAll(){
var itemInfo = '';
/* display data:
use a for loop to go through each element in the item_list array
Each element is an object.
*/
for (var i=0; i<item_list.length; i++){
// use each item to create HTML content
itemInfo += createItemData(item_list[i], i);
// add each item to the table
$('#item-list').html(itemInfo);
}
}
function createItemData(item, index){
/* Use the data-attribute to add the index of each element of the array so that each checkbox can be mapped to
the corresponding item. Then we can directly use the array of item objects to prepare a suitable
HTML structure and add to the shopping cart.
*/
var trow = "<tr class='itemlist data-index='" +index+ "' >";
trow += "<td class=item-title'><input type='checkbox' class='addme' data-index='"+ index +"' > "+item.title + "</td>";
trow += "<td class='item-description'>"+item.description + "</td>";
trow += "<td class='price'>"+item.price + "</td></tr>";
return trow;
}
$('#item-list').on('click', '.addme', function(){
/* Whenever a item is selected by clicking on any of the checkboxes, perform the following: */
// 1. Read the item index using data- attribute
var index = $(this).data('index');
// 2. If the checkbox is checked then add the item to the cart. Else, remove it from the cart
if ($(this).prop('checked')){
cart.push(index);
} else {
removeItemFromCart(index);
}
// 3. Update the cart list and total credits
displayCartItems();
// update price
calculateTotalPrice();
});
$('#selected-list').on('click', '.delete-item', function(){
var index = $(this).val();
removeItemFromCart(index);
calculateTotalPrice();
checkCartElements();
});
$("#selected-list").on('change', '.quantity', calculateTotalPrice);
function calculateTotalPrice(){
var subtotal = calculateSubtotal();
var tax = calculateTax();
var shipping = calculateShipping();
var total = calculateTotal();
$('#subtotal').html(subtotal.toFixed(2));
$('#tax').html(tax.toFixed(2));
$('#shipping').html(shipping.toFixed(2));
$('#total').html(total.toFixed(2));
}
function calculateSubtotal(){
var subtotal = 0;
var quantity = 1;
for(var i = 0; i < cart.lengh; i++){
quantity = parseInt($(this).val());
var productPrice = parseInt(item_list[cart[i]].price);
subtotal += parseInt(productPrice * quantity);
}
alert(quantity);
return subtotal;
}
function calculateTax(){
var taxAmount = 0;
var taxes = .06;
var subtotal = calculateSubtotal();
taxAmount = parseInt(subtotal * taxes);
return taxAmount;
}
function calculateShipping(){
var shippingAmount = 0;
var shippingPerc = .02;
var subtotal = calculateSubtotal();
shippingAmount = parseInt(subtotal * shippingPerc);
return shippingAmount;
}
function calculateTotal(){
var totalCost = 0;
var subtotal = calculateSubtotal();
var taxes = calculateTax();
var shippingCost = calculateShipping();
totalCost = parseInt(subtotal + taxes + shippingCost);
return totalCost;
}
function removeItemFromCart(index){
// identify and remove the index from the cart and redisplay cart table
var pos = -1;
for (var i=0; i<cart.length; i++){
if (index == cart[i]){
pos = i;
break;
}
}
if (pos>-1){
cart.splice(pos, 1);
// reset the cart table
displayCartItems();
} else {
alert("Could not find!");
}
}
function displayCartItems(){
// create a table row for each item in cart array
var itemInfo = '';
for (var i=0; i<cart.length; i++){
var index = cart[i];
itemInfo += createTableRow(index);
}
$('#selected-list').html(itemInfo);
}
/*function createTableRow(index){
var trow = '';
trow+= "<tr><td>"+item_list[index].title + "</td>>";
trow += "<td>"+item_list[index].price + "</td>";
trow += "<td><input type='text' id='quantity' value='1' size='5' />";
trow += "<td><button type='button' class='delete-item' value='"+index+"'>Delete</button></td></tr>";
return trow;
}*/
function createTableRow(index){
var trow = '';
trow+= "<tr><td>"+item_list[index].title + "</td>>";
trow += "<td>"+item_list[index].price + "</td>";
trow += "<td><input type='text' class='quantity' value='1' size='5' />";
trow += "<td><button type='button' class='delete-item' value='"+index+"'>Delete</button></td></tr>";
return trow;
}
$('#show-cart').on('click', function(){
$('#selected-list').show();
});
$('#hide-cart').on('click', function(){
$('#selected-list').hide();
});
});
</script>
</head>
<body>
<div class='container'>
<div class='row' id='top-box' >
<div class='col-sm-12'>
<h2>Sam's Discount Store</h2>
<h3>Variety of Items!</h3>
</div>
</div>
<div class='row' id='content'>
<div class='col-sm-8'>
<h3 class='title'>Discounted Items</h3>
<h4>
<select id='category'>
<option value='0' >All</option>
<option value='baseballgear' >Baseball Items</option>
<option value='soccergear' >Soccer Items</option>
<option value='videogames'>Video Games</option>
</select>
</h4>
<table class='table table-bordered clmlabels' >
<tr class='t-head'><td >Product</td>
<td >Description</td>
<td >Cost</td>
</tr>
<tbody id='item-list'>
</tbody>
</table>
</div>
<div class='col-sm-4'>
<h2>Cart Items</h2>
<p><button class='btn btn-primary' id='show-cart'>Display cart</button>
<button class='btn' id='hide-cart'>Hide cart</button></p>
<table class='table selected-list' id='selected-list'>
</table>
</div>
<table class='cart-table'>
<tr>
<td>Subtotal: </td>
<td><span id='subtotal'>0</td>
</tr>
<tr>
<td>Tax: </td>
<td><span id='tax'>0</td>
</tr>
<tr>
<td>Shipping: </td>
<td><span id='shipping'>0</td>
</tr>
<tr>
<td>Total: </td>
<td><span id='total'>0</td>
</tr>
</table>
</div>
</div>
<div class='row' id='footer'
<div class='col-sm-12'> <p>Sam's Discount Store</p></div>
</div>
</div>
</body>
</html>
答案 0 :(得分：0)
你错误拼写了＃34; cart.lengh＆＃34; （应为cart.length）（第185行）。 然后在调用方法＆＃34; calculateSubtotal＆＃34;从方法＆＃34; calculateTotalPrice＆＃34;，当您尝试使用$（this）来获取数量时，上下文会丢失。一种解决方案是在方法中获得输入值＆＃34; calculateTotalPrice＆＃34;并将其作为参数传递给方法＆＃34; calculateSubTotal＆＃34;。
function calculateTotalPrice(){
var quantity = parseInt($(this).val());
var subtotal = calculateSubtotal(quantity);
}
function calculateTotalPrice(quantity){}