/* Taken from http://www.codetoad.com/javascript/isempty.asp 
 * Check whether input field is empty */
function IsEmpty(aTextField)
{
   if ((aTextField.value.length==0) ||
   (aTextField.value==null)) {
      return true;
   }
   else { return false; }
}	

function validateCommentForm( formID ) {
  // debugger;
  Message = '';
  form = document.getElementById( formID );
  /* Name */
  u_is_empty = IsEmpty( form.u ) ;
  /* e-mail address */
  i_is_empty = IsEmpty( form.i ) ;
  /* Comment content */
  p_is_empty = IsEmpty( form.p ) ;

  if( u_is_empty || i_is_empty || p_is_empty ) {
    if( u_is_empty ) { 
      form.u.className += ' empty-field' ;
      Message +=  "input field 'Name' is empty\n" ;
    }

    if( i_is_empty ) {
      form.i.className += ' empty-field' ;
      Message +=  "input field 'e-mail' is empty\n" ;
    }
    if( p_is_empty ) {
      form.p.className += ' empty-field' ;
      Message +=  "Comment content is empty!\n" ;
    }

    Message += "\nPlease correct these errors and re-submit your comment.";
    alert( Message );
    return false;
  }
  return true;
}