function checkComments() {
  if($('txt_name') && $('txt_name').value == '') {
    alert("Name is required");
    $('txt_name').focus();
    return false;
  }

  if($('txt_email')) {
    var pattern = /^[a-zA-Z0-9._-]+@[a-zA-Z0-9._-]+\.[a-zA-Z]{2,5}$/;

    if(!pattern.test($('txt_email').value)) {
      alert("A valid email address is required");
      $('txt_email').focus();
      return false;
    }
  }

  if($('txt_comment').value == '') {
    alert("A comment is required");
    $('txt_comment').focus();
    return false;
  }

  return true;
}

window.onload = function() {
  if($('comment_form')) {
    $('comment_form').onsubmit = function() { return checkComments(); };
  }
};