var xmlhttp;
var categoryID = -1;

function showSubCategories(catID)
{
  xmlhttp=GetXmlHttpObject();
  if (xmlhttp==null) 
  {
    alert("Prosím povoľte JavaScript vo Vašom prehliadači");
    return;
  }
  categoryID = catID;
  
  //hide text in category
  if (categoryID > -1) {
    var txt = document.getElementById("category-" + categoryID).innerHTML;
    if (txt != null && txt != "") {
      document.getElementById("category-" + categoryID).innerHTML = "";
      return;
    }
  }  
  
  var url="ajax_registracia.php";
  url=url+"?catID="+categoryID;
  url=url+"&sid="+Math.random();
  xmlhttp.onreadystatechange=subCategoriesStateChanged;
  xmlhttp.open("GET",url,true);
  xmlhttp.send(null);
}

function subCategoriesStateChanged()
{
  if (xmlhttp.readyState==4)
  {
    if (categoryID > -1) {
      document.getElementById("category-" + categoryID).innerHTML=xmlhttp.responseText;
    }
  }
}

function GetXmlHttpObject()
{
if (window.XMLHttpRequest)
  {
  // code for IE7+, Firefox, Chrome, Opera, Safari
  return new XMLHttpRequest();
  }
if (window.ActiveXObject)
  {
  // code for IE6, IE5
  return new ActiveXObject("Microsoft.XMLHTTP");
  }
return null;
}

function toggleAddForm()
{
  var formObj = document.getElementById("new-form");
  var visibility = formObj.style.display;
  
  if (visibility == "block" || visibility == "inline") {
    formObj.style.display = "none";
  } else {
    formObj.style.display = "block";
  }
}