function addToCart(cat_id, product_id){
	var xmlreq = xmlhttp();
	var queryString = "cat_id="+cat_id+"&product_id=" + product_id;
	//alert(queryString);
	xmlreq.onreadystatechange=function()
	{
	if(xmlreq.readyState==4)
	  {
	   //alert(xmlreq.responseText);
	   updateCartDisplay();
	  }
	}
	xmlreq.open("GET","includes/addtocart_ajax.php?" + queryString ,true);
	xmlreq.send(null);
 }

function updateCartDisplay(){
	var xmlreq = xmlhttp();
	xmlreq.onreadystatechange=function()
	{
	if(xmlreq.readyState==4)
	  {
	  cart_contents = xmlreq.responseText;
	  cart = document.getElementById('shopping_cart');
	  if(cart){
	  cart.innerHTML = cart_contents;
	  //alert(cart.innerHTML);
	  }
	  }
	}
	xmlreq.open("GET","includes/getcart_ajax.php",true);
	xmlreq.send(null);
 }
function removeFromCart(i){
	document.getElementById('preview').style.display = "none";
	var xmlreq = xmlhttp();
	var query = "index=" + i;
	xmlreq.onreadystatechange=function()
	{
	if(xmlreq.readyState==4)
	  {
		//alert(xmlreq.responseText);
		updateCartDisplay();
	  }
	}
	xmlreq.open("GET","includes/removefromcart_ajax.php?" + query ,true);
	xmlreq.send(null);
}