function isDate(dateStr) {
    var datePat = /^(\d{1,2})(\/|.)(\d{1,2})(\/|.)(\d{4})$/;
    var matchArray = dateStr.match(datePat); // is the format ok?

    if (matchArray == null) {
        //alert("Please enter date as either mm/dd/yyyy or mm.dd.yyyy.");
        return false;
    }

    day = matchArray[1]; // parse date into variables
    month = matchArray[3];
    year = matchArray[5];

    if (day < 1 || day > 31) {
        //alert("Day must be between 1 and 31.");
        return false;
    }

    if ((month==4 || month==6 || month==9 || month==11) && day==31) {
        //alert("Month "+month+" doesn't have 31 days!")
        return false;
    }

    if (month == 2) { // check for february 29th
        var isleap = (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0));
        if (day > 29 || (day==29 && !isleap)) {
            //alert("February " + year + " doesn't have " + day + " days!");
            return false;
        }
    }

    if (month < 1 || month > 12) { // check month range
        //alert("Month must be between 1 and 12.");
        return false;
    }

    return true; // date is valid
}

function isNumeric(InString)
{
   //RefString = "-1234567890.,";
   // Pro nase potreby jen prirozena cisla
   RefString = "1234567890";
   DecimalPoints = 0;
   
   if (InString.length == 0)
    return (false);	

   for (i=0; i < InString.length; i++)
   {
      TempChar = InString.substring ( i, i+1 );

      if ( TempChar == "." ) { DecimalPoints++; } /* Can only have zero or one decimal points in a number */
      if (( TempChar == "-" ) && ( i != 0 )) { return ( false ); } /* Minus Sign must be first character */

      /* Check if current character is valid */

      if ( RefString.indexOf (TempChar,0) == -1)
      {
         /* character not found in RefString */
         return (false);
      }
   }
   if ( DecimalPoints > 1 )
      return ( false );

   return(true);
}


function isEmailAddress(EmailAddress)
{
  var mail=/^.+@.+\..{2,4}$/ 
  return (mail.test(EmailAddress));
}

function zobrazURL(URL, sirka, vyska, zleva, shora) 
{
  window.open(URL, '', 'width=' + sirka + ', height=' + vyska + ', left=' + zleva + ', screenX=' + zleva + ', top=' + shora + ', screenY=' + shora + ', scrollbars=yes, resizable=yes');
}

function sipky(e, item)
{
 if (e.keyCode == 38)
 {
  item.value = (Number(item.value) + 1).toString();
  e.returnValue=false;
 };
 if (e.keyCode == 40)
 {
  if (Number(item.value) > 1)
  {
   item.value = (Number(item.value) - 1).toString();
   e.returnValue=false;
  }
 };
}