Login: Button is deactivated, when both inputs are empty

views/default/login.html

@@ -3,12 +3,27 @@
 <form id="form_login">
     <input type="text" id="room_code" placeholder="{{=T('Enter Room Code')}}" maxlength="4"><br><br>
     <input type="text" id="user_name" placeholder="{{=T('Enter your Name')}}" maxlength="15"><br><br>
-    <input class="btn btn-outline-primary" type="submit" value="{{=T('Play')}}">
+    <input class="btn btn-outline-primary" disabled type="submit" value="{{=T('Play')}}">
 </form>
 
 <script type="text/javascript">
     //Header setzen
     HEADER_SET("", "Lynchburg", "");
+    //Button aktivieren, falls beide Felder gefüllt sind
+    $('#form_login input[type="text"]').keyup(function() {
+    var empty = false;
+    //Falls ein Feld leer ist, setze empty auf true
+    $('#form_login input[type="text"]').each(function() {
+        if ($(this).val().length == 0) {
+            empty = true;
+        }
+    });
+    if (empty) {
+        $('#form_login input[type="submit"]').attr('disabled', 'disabled');
+    } else {
+        $('#form_login input[type="submit"]').removeAttr('disabled');
+    }
+  });
     //Bei Absenden des Formulars...
     $("#form_login").on("submit", function(){
         //Entfernt die Anzeige der bisherigen Fehler