if (firstname.length < 3) firstname_eror = "Имя не меньше 3 символов";
if (lastname.length < 3) lastname_eror = "Имя не меньше 3 символов";
if (email_address.split ('@').length - 1 == 0 || email_address.split ('.').length - 1 == 0) fail = "Вы ввели некорректный адрес эл. почты";

if (firstname_eror != "") {
$('#firstname_eror').html (firstname_eror + "<div class='clear'><br></div>");
$('#firstname_eror').show ();

}
if (lastname_eror != "") {
$('#lastname_eror').html (lastname_eror + "<div class='clear'><br></div>");
$('#lastname_eror').show ();

}