public/static/js/maps.js

@@ -112,6 +112,7 @@
         document.getElementById('playMode').style.visibility = 'hidden';
     }
 
+    if (document.getElementById('challengeButton')) {
         document.getElementById('challengeButton').onclick = function () {
             MapGuesser.showModal('challenge');
             document.getElementById('createNewChallengeButton').href = '/challenge/new/' + this.dataset.mapId;
@@ -119,6 +120,7 @@
             
             var timeLimit = document.getElementById('timeLimit').value;
             document.getElementById('timeLimitLabel').innerText = 'Time limit of ' + timeLimit + ' seconds per round';
+        };
     }
 
     document.getElementById('closePlayModeButton').onclick = function () {

src/Controller/MapsController.php

@@ -48,6 +48,7 @@ class MapsController
         $user = $this->request->user();
         return new HtmlContent('maps', [
             'maps' => $maps,
+            'isLoggedIn' => $user !== null,
             'isAdmin' => $user !== null && $user->hasPermission(IUser::PERMISSION_ADMIN)
         ]);
     }

views/maps.php

@@ -11,8 +11,10 @@ TODO: condition!
     <a id="singleButton" class="button fullWidth marginTop" href="" title="Single player">Single player</a>
     <p class="bold center marginTop marginBottom">OR</p>
     <button id="multiButton" class="fullWidth green" data-map-id="">Multiplayer (beta)</button>
+    <?php if ($isLoggedIn): ?>
         <p class="bold center marginTop marginBottom">OR</p>
         <button id="challengeButton" class="fullWidth yellow" data-map-id="" data-timer="">Challenge (gamma)</button>
+    <?php endif; ?>
     <div class="right">
         <button id="closePlayModeButton" class="gray marginTop" type="button">Close</button>
     </div>