// JavaScript Document
// Holds an instance of XMLHttpRequest
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)
			{
				// ignore potential error
			}
		}
	}
	
	// return the created object or display an error message
	if(!xmlHttp)
	{
		alert("Error creating the XMLHttpRequest object.");
	}
	else
	{
		return xmlHttp;
	}
}

// Read a file from the server
function process(t,c)
{
	// Only continue if xmlHttp isn't void
	if(xmlHttp)
	{
		// Try to connect to the server
		try
		{
			// Get the two variables
			//var table = t;
			//var cta = c;
			
			// Create the params string
			var params = "table=" + t + "&cta=" + c;			
			
			// Initiate the asynchronous HTTP request
			xmlHttp.open("GET","/ajax-cta.php?" + params,true);
			xmlHttp.onreadystatechange = handleRequestStateChange;
			xmlHttp.send(null);
		}
		catch(e)
		{
			// Display the error in case of failure
			//alert("Can't connect to server:\n" + e.toString());
		}
	}
}

// Functioncalled when the state of the HTTP request changes
function handleRequestStateChange()
{
	// When readystate is 4, we are ready to read the server response
	if(xmlHttp.readyState == 4)
	{
		// Continue only if HTTP status is OK
		if(xmlHttp.status == 200)
		{
			try
			{
				// Do something with the response from the server
				handleServerResponse();
			}
			catch(e)
			{
				// Display error message
				//alert("Error reading the response: " + e.toString());
			}
		}
		else
		{
			// Display stauts message
			//alert("There was a problem retrieving the data:\n" + xmlHttp.statusText);
		}
	}
}

// Handles the response received from the server
function handleServerResponse()
{
	// Retrieve the server's response
	var response = xmlHttp.responseText;	
}