function checkuser() {
                var user = _("username")
                if (!empty(user.value)) {
                    $.ajax({
                        url: "checkUsername.php",
                        async: true,
                        type: "POST",
                        data: {user: user.value},
                        beforeSend: function () {
                            _("serror").innerHTML = "checking...";
                        },
                        success: function (data) {
                            if (data == 1) {
                                _("serror").innerHTML = "<b style='color:red'>Username Taken</b>";
                            } else {
                                _("serror").innerHTML = "<b style='color:green'>Username OK</b>";
                            }
                        }
                    })
                } else {
                    _("serror").innerHTML = "";
                }
            }