function getXMLHttpRequestObject()
{
  try{
    return new XMLHttpRequest();
  }
  catch(e){
    try{
      return new ActiveXObject("Microsoft.XMLHTTP");
    }
    catch(e){
      return false;
    }
  }
}

function startGETRequest(url, onComplete, onEnd)
{
  var XMLHttpRequestObject = getXMLHttpRequestObject();
  if(XMLHttpRequestObject){
    XMLHttpRequestObject.open("GET", url);
    XMLHttpRequestObject.onreadystatechange = function()
    {
      if (XMLHttpRequestObject.readyState == 4){
        if(XMLHttpRequestObject.status == 200){
          var responseXML = XMLHttpRequestObject.responseXML;
          var responseText = XMLHttpRequestObject.responseText;
          onComplete(responseText, responseXML);
        }
        delete XMLHttpRequestObject;
        onEnd();
      }
    }
    XMLHttpRequestObject.send(null);
  }
}

function startPOSTRequest(url, params, onComplete, onEnd)
{
  var XMLHttpRequestObject = getXMLHttpRequestObject();
  if(XMLHttpRequestObject){
    XMLHttpRequestObject.open("POST", url);
    XMLHttpRequestObject.setRequestHeader(
      'Content-Type', 'application/x-www-form-urlencoded');
    XMLHttpRequestObject.onreadystatechange = function()
    {
      if (XMLHttpRequestObject.readyState == 4){
        if(XMLHttpRequestObject.status == 200){
          var responseXML = XMLHttpRequestObject.responseXML;
          var responseText = XMLHttpRequestObject.responseText;
          onComplete(responseText, responseXML);
        }
        delete XMLHttpRequestObject;
        onEnd();
      }
    }
    XMLHttpRequestObject.send(params);
  }
}

//===================================================================================================

function listaOpcjiChange() {
	var div = document.getElementById("dataDiv");
	var listaOpcji = document.getElementById("listaOpcji");
	var str = listaOpcji[listaOpcji.selectedIndex].value;
	div.innerHTML = str;
}

function startRequest(zestaw) {
	var btnZestaw1 = document.getElementById('btnZestaw1');
	var btnZestaw2 = document.getElementById('btnZestaw2');
	btnZestaw1.disabled = true;
	btnZestaw2.disabled = true;

	url = "skrypt.php?zestaw=" + zestaw;
	url = encodeURI(url);
	startGETRequest(url, onComplete, onEnd); // ??
}

function onEnd() {
	var btnZestaw1 = document.getElementById('btnZestaw1');
	var btnZestaw2 = document.getElementById('btnZestaw2');
	btnZestaw1.disabled = false;
	btnZestaw2.disabled = false;
}

function onComplete(text, xml) {
	var arr = text.split(':');
	if(arr[0] != 'error') {
		var listaOpcji = document.getElementById("listaOpcji");
		listaOpcji.options.length = 0;
		listaOpcji[0] = new Option("Wybierz jedną z opcji", "");
		for(i = 0; i < arr.length; i++) {
			listaOpcji[i + 1] = new Option(arr[i], arr[i]);
		}
	}
	else
	{
		if(arr.length == 2) {
			alert(arr[1]);
		}
		else
		{
			alert("Wystąpił błąd podczas przetwarzania danych...");
		}
	}
}