var xmlCart;

function addToCart(item) {
	xmlCart = new XmlHttpRequestWrapper('updateCart('+item+')','');
	xmlCart.loadDocument('add_to_cart.php?id='+item);
}

function updateCart(item) {
	if ( ! xmlCart.getRequest().responseXML ) {
		alert('Unable to add item to the cart.');
	} else {
		try {
			var cartDoc = xmlCart.getRequest().responseXML.documentElement;
			var contents = cartDoc.getElementsByTagName('contents')[0];
			var quantity = contents.attributes.getNamedItem('quantity').value;
			var cost = contents.attributes.getNamedItem('cost').value;
			var cartContents = document.getElementById('cartContents');
			cartContents.innerHTML = (quantity==1 ? '1 item, $' : quantity+' items, $') + cost;
			document.getElementById('addToCart'+item).innerHTML = '<img src="images/check.gif" alt="Added to Cart" align="absmiddle" /> Added to cart <a href="?page=cart">Go &gt;</a>';
		} catch ( e ) {
			alert(e.message);
		}
	}
}