...
<tr>
<!-- Item details -->
<td>Hat</td> <td>Stylish bowler hat</td> <td>$19.99</td>
<td>
<!-- Click button to add item to cart via Ajax request -->
<button onclick="addToCart('hat001')">Add to Cart</button>
</td>
</tr>
...
<!-- Representation of shopping cart, updated asynchronously -->
<ul id="cart-contents">
<!-- List-items will be added here for each item in the cart -->
</ul>
<!-- Total cost of items in cart displayed inside span element -->
Total cost: <span id="total">$0.00</span>
Ajax处理过程
