Hi All, I am trying to build a shopping cart site. When a user click add to cart image on the product page, The product title will show a "The product is in your cart" text without reloading the page. I am using session and ajax but no luck so far. I appreciate any helps.

My html cold

 <table id="<?php echo $productId; ?>" width="594" border="0" cellpadding="5" cellspacing="0">
    <tr>
                <td><img src="<?php echo "$brandImage"; ?></td>
    <td <?php echo $productName; ?>  //The "The product is in your cart" will be showed here</td>
        </tr> 
<tr>
<td><a class="addToCart" href="javascript:void(0);" onclick="addToCart(<?php echo $productId?>)"> 
</td>

My Javascript file (addToCart.js)

   function addToCart(productId){

var url="addToCart.php";
url=url+"?productId="+productId;
url=url+"&sid="+Math.random();


$.post(
 url,
 function(responseText){
  alert(responseText); //I wish I can get productData value from addToCart.php
 },
 "html"
)

My php file (addToCart.php)

   <?php SESSION_START();

$productId=$_GET['productId'];
$cart=$_SESSION['cart'];

if(isset($cart)){
 $cart.=",".$productId;
 $product=explode(',',$cart);
 $totalItem=count($product);

}else{
 $cart=$productId;
 $totalItem=1;

};
$productData=array();
foreach($product as $id){
$productData[$id]=(isset($productData[$id])) ? $productData[$id]+1 :1;
};
$_SESSION['cart']=$cart;
//print_r($productData);
echo $productData; //Not sure what to do to send $productData back to my addToCart.js variable




?>

I tried to make the code look simple. Any suggestion will be a great help. Thanks