function validateForm ()
{
  re = new RegExp("^[^.]+(\.[^.]+)*@([^.]+[.])+[a-z]{2,4}$");
	requiredFields = getElementsByClassName("required","req_active");
  var first = "";
  var warning = 0;
	for (var i=0;i<requiredFields.length;i++)
	{
		if ( requiredFields[i].value == "" || requiredFields[i].value == 0 ){
				if (first == "") first = requiredFields[i];
				requiredFields[i].className = requiredFields[i].className.replace(/required/,' req_active');
				warning = 1;
		}
    else { 
      requiredFields[i].className = requiredFields[i].className.replace(/req_active/,' required');
      if (requiredFields[i].id == 'kontakt_email' || requiredFields[i].id == 'email') {
          if (!re.test(requiredFields[i].value)){
                  requiredFields[i].className = requiredFields[i].className.replace(/required/,' req_active');
                  if (first == "") first = requiredFields[i];
                  warning = 1;
          }
      }
    }
	}
	if (warning == 0) return true;
  else {		
      first.focus();
      alert('Některé povinné položky jsou chybně vyplněny.');
			return false;
  }
}


function getElementsByClassName(className1,className2) 
{ 
	var arr = new Array(); 
	var elements = document.getElementsByTagName("*");
	for ( var i = 0; ( element = elements[i] ); i++ )
	{
		if ( (element.className.indexOf(className1) != -1) || (element.className.indexOf(className2) != -1) )
		{
			arr[arr.length] = element;
		}
	}
	return arr;
}