function getXMLHTTPRequest()
//funkcja tworząca objekt XMLHTTPRequest dla każdej przeglądarki
{
  var req = false;
  try
  { req = new XMLHttpRequest(); }
  catch(err1)
	{
	  try
	  { req = new ActiveXObject("Msxml2.XMLHTTP"); }
	  catch(err2)
	    {
	    try
	      { req = new ActiveXObject("Microsoft.XMLHTTP"); }
	      catch(err3)
		    { req = false; 
		    }
	    }
	}
  return req;
}

var myRequest = getXMLHTTPRequest();

function callAjax(url) {
  var myRand = new Date().getTime();
  myRequest.open("GET", url+"&rand="+myRand, true);
  myRequest.onreadystatechange = responseAjax;
  myRequest.send(null);
}

function responseAjax() {
  if(myRequest.readyState == 4) {
    if(myRequest.status == 200) {
	   var beginchar = myRequest.responseText.lastIndexOf("<!-- shopping_cart //-->");
	   var endchar =  myRequest.responseText.lastIndexOf("<!-- shopping_cart_eof //-->");
	   document.getElementById('Shopping_cart').innerHTML = myRequest.responseText.substring(beginchar, endchar);
      //document.getElementById('Shopping_cart').innerHTML = myRequest.responseText.getElementById('Shopping_cart').innerHTML;
	  document.getElementById('loader').style['display'] = 'none';
	} else {
	  alert("Wystąpił błąd: "+myRequest.statusText);
	}
  } else {
	  if (window.innerWidth)
        var x = (window.innerWidth/2)-150;
	  else var x = (document.body.clientWidth/2)-150;
      if (window.innerHeight)
	    var y = ((window.innerHeight/2)-75)+window.pageYOffset;
	  else var y = ((document.body.clientHeight/2)-75)+document.body.scrollTop;
      
      document.getElementById('loader').style['display'] = 'block';
      document.getElementById('loader').style.left = x+'px';
      document.getElementById('loader').style.top = y+'px';
  }
}