function sizeTbl(tbl_id) {
  var tbl = document.getElementById(tbl_id);
  if (tbl.style.display == 'none') {
    tbl.style.display = 'block';
  } else {
    tbl.style.display = 'none';
  }
}

function validEmail(email) {
  var needed=/^.+@.+\..{2,3}$/;
  if (!needed.test(email))
    return false;
  else
    return true;
}

function checkForm (f) {
  var result = true;
  var errors = "";

  if (!validEmail(f.contact_email.value)) {
    errors += "Please enter a valid email address.\n";
    result = false;
  }

  if (!f.comments.value) {
    errors += "Please enter some comments for your response.\n";
    result = false;
  }

  if (result == false) {
    alert(errors);
  }
  return result;
}