/// \fnc isEmpty( elem, msg )
///
/// \brief Returns true if element is empty.
///
function isEmpty( elem, msg )
{

  if(elem.value.length == 0) {
  
    alert(msg);
    elem.focus();   // Set focus to bad filled element.
    return true;
    
  } else {
  
    return false;
    
  };

}

/// \fnc  isNumber( elem, msg )
///
/// \brief Returns true is element is numberic string of letters '0'..'9'.
///
function isNumber( elem, msg )
{
  var numericExpression = /^[0-9]+$/;
  if(elem.value.match(numericExpression)) {
  
    return true;
    
  } else {
  
    alert(msg);
    elem.focus();
    return false;
    
  };
   
}

/// \fnc  isAlphabet( elem, msg )
///
/// \brief Returns true is element is alphabet string of letters 'a'..'z','A'..'Z'.
///
function isAlphabet( elem, msg )
{
  /*
  var numericExpression = /^[a-zA-Z]+$/;
  if(elem.value.match(numericExpression)) {
  
    return true;
    
  } else {
  
    alert(msg);
    elem.focus();
    return false;
    
  };
  */  
  
  return true;
  
}

/// \fnc  isAlphaNumeric( elem, msg )
///
/// \brief Returns true is element is alphanumeric string of letters '0'..'9','a'..'z','A'..'Z'.
///
function isAlphaNumeric( elem, msg )
{
  /*
  var numericExpression = /^[0-9a-zA-Z]+$/;
  if(elem.value.match(numericExpression)) {
  
    return true;
    
  } else {
  
    alert(msg);
    elem.focus();
    return false;
    
  };
  */
  
  return true;
   
}

/// \fnc    lengthRestriction( elem, min, max )
///
/// \brief  Returns true, if element has length in range [min, max].
///
function lengthRestriction( elem, min, max, msg )
{
  /*
  var uInput = elem.value;
  if( (uInput.length >= min) && (uInput <= max) ) {
  
    return true;
    
  } else {
  
    alert(msg);
    elem.focus();
    return false;
    
  };
  */
  
  return true;
  
}


/// \fnc  OtevriChatOkno()
///
/// \brief Otvori okno s chat modulom.
///
function OtevriChatOkno()
{
window.open('chat/index.php','CHAT',
' toolbar=0, location=0,scrollbars=0, resizable=0, top=0, left=0, width=702, height=600');
}