/**
 * Zmienne i funkcje dotyczące mechanizmu AJAX.
 */

/* Ajax variable. */
var req;
/* Ajax variable. */
var response;
/*
 *	Main Ajax functions.
 */
function loadXMLDoc(url, callback) 
{
/*
http.abort;
http.open('post',  'back_end.php');
http.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
http.send('arg1=val1&arg2=val2&arg3=val3');
*/
    req = null;
    
    if(window.XMLHttpRequest)
    {

	    try
	    {
			req = new XMLHttpRequest();
	    }
		catch(e)
	    {
			alert("new XMLHttpRequest()");
			req = null;
        }

        if(req)
    	{
                req.onreadystatechange = callback;

                req.open("GET", url);

                req.send(null);

        }
    }
	else if(window.ActiveXObject)
    {

	    try
	    {
        	req = new ActiveXObject("Msxml2.XMLHTTP");
	    }
		catch(e)
	    {
			try
			{
          	    req = new ActiveXObject("Microsoft.XMLHTTP");
	        }
			catch(e)
			{
				alert("new XMLHttpRequest()");
                    req = null;
        	}
        	alert("new XMLHttpRequest()");
	    }

        if(req)
        {
			req.onreadystatechange = callback;
            req.open("GET", url, true);
            req.send();

        }
    }
}

/**
 * Szkielet funkcji obsługującej mechanizmu AJAX.
 */
function handleAjax()
{

	if(req.readyState == 4)//if (req.status == 200)
	{
		var response = req.responseText;
	
		alert(response);
	}
}