// stores the reference to the XMLHttpRequest object
var xmlHttp = createXmlHttpRequestObject();

// creates an XMLHttpRequest instance
function createXmlHttpRequestObject()
{
	// will store the reference to the XMLHttpRequest object
	var xmlHttp;
	
	// this should work for all browsers except IE6 and older
	try
	{
		// try to create XMLHttpRequest object
		xmlHttp = new XMLHttpRequest();
	}
	catch(e)
	{
		// assume IE6 or older
		var XmlHttpVersions = new Array("MSXML2.XMLHTTP.6.0",
										"MSXML2.XMLHTTP.5.0",
										"MSXML2.XMLHTTP.4.0",
										"MSXML2.XMLHTTP.3.0",
										"MSXML2.XMLHTTP",
										"Microsoft.XMLHTTP");
										
		// try every prog id until one works
		for (var i=0; i<XmlHttpVersions.length && !xmlHttp; i++)
		{
			try
			{
			// try to create XMLHttpRequest object
			xmlHttp = new ActiveXObject(XmlHttpVersions[i]);
			} catch (e) {}
		}
	}
	
	// return the created object or display an error message
	if (!xmlHttp)
		alert("Error creating the XMLHttpRequest object.");
	else
		return xmlHttp;
}
	
// make asynchronous HTTP request using the XMLHttpRequest object
function process()
{
	// proceed only if the xmlHttp object isn't busy
	if (xmlHttp.readyState == 4 || xmlHttp.readyState == 0)
	{

		// execute the quickstart.php page from the server
		xmlHttp.open("GET", "ajax_cart.php", true);
		// define the method to handle server responses
		xmlHttp.onreadystatechange = handleServerResponse;
		// make the server request
		xmlHttp.send(null);
	}
	else
		// if the connection is busy, try again after one second
		setTimeout('process()', 1000);
}
		
// executed automatically when a message is received from the server
function handleServerResponse()
{
	// move forward only if the transaction has completed
	if (xmlHttp.readyState == 4)
	{
		// status of 200 indicates the transaction completed successfully
		if (xmlHttp.status == 200)
		{
			// extract the XML retrieved from the server
			xmlResponse = xmlHttp.responseXML;
			
			// obtain the document element (the root element) of the XML structure
			xmlDocumentElement = xmlResponse.documentElement;
			
			// get the text message, which is in the first child of
			// the the document element

			ItemArray  = xmlDocumentElement.getElementsByTagName("itemTotal");
			PriceArray = xmlDocumentElement.getElementsByTagName("priceTotal");
			
			TotalItems	=	ItemArray.item(0).firstChild.data;
			TotalPrice	=	PriceArray.item(0).firstChild.data;
			
			document.getElementById("divItems").innerHTML = TotalItems ;
			document.getElementById("divPrice").innerHTML = TotalPrice ;
													
			// restart sequence
			setTimeout('process()', 1000);
		}
		// a HTTP status different than 200 signals an error
		else
		{
			alert("There was a problem accessing the server: " + xmlHttp.statusText);
		}
	}
}