warn in case of lacking client-side SSE support

app/assets/javascripts/editor.js

@@ -330,6 +330,10 @@ $(function() {
     return isActiveFileExecutable() && ['teacher_defined_test', 'user_defined_test'].includes(active_frame.data('role'));
   };
 
+  var isBrowserSupported = function() {
+    return window.EventSource !== undefined;
+  };
+
   var populatePanel = function(panel, result, index) {
     panel.removeClass('panel-default').addClass(getPanelClass(result));
     panel.find('.panel-title .filename').text(result.filename);
@@ -631,6 +635,8 @@ $(function() {
   };
 
   if ($('#editor').isPresent()) {
+    if (isBrowserSupported()) {
+      $('.score, #development-environment').show();
       configureEditors();
       initializeEditors();
       initializeEventHandlers();
@@ -639,5 +645,8 @@ $(function() {
       renderScore();
       showFirstFile();
       showRequestedTab();
+    } else {
+      $('#alert').show();
+    }
   }
 });

app/assets/stylesheets/editor.css.scss

@@ -16,6 +16,14 @@ button i.fa-spin {
   }
 }
 
+.score {
+  display: none;
+}
+
+#alert, #development-environment {
+  display: none;
+}
+
 #editor-buttons {
   background-color: #008CBA;
   margin-top: 1em;

app/views/exercises/implement.html.slim

@@ -4,6 +4,11 @@ span.badge.pull-right.score
 
 p.lead = @exercise.description
 
+#alert.alert.alert-danger role='alert'
+  h4 = t('.alert.title')
+  p = t('.alert.text', application_name: application_name)
+
+#development-environment
   ul.nav.nav-justified.nav-tabs role='tablist'
     li.active
       a data-placement='top' data-toggle='tab' data-tooltip=true href='#instructions' role='tab' title=t('shared.tooltips.shortcut', shortcut: 'ALT + 1')

config/locales/de.yml

@@ -188,6 +188,9 @@ de:
     form:
       add_file: Datei hinzufügen
     implement:
+      alert:
+        text: 'Ihr Browser unterstützt nicht alle Funktionalitäten, die %{application_name} benötigt. Bitte nutzen Sie einen modernen Browser, um %{application_name} zu besuchen.'
+        title: Ihr Browser wird nicht unterstützt!
       default_feedback: Sehr gut. Alle Tests waren erfolgreich.
       feedback: Feedback
       file: 'Test-Datei <span class="number">%{number}</span> (<span class="filename">%{filename}</span>)'

config/locales/en.yml

@@ -188,6 +188,9 @@ en:
     form:
       add_file: Add file
     implement:
+      alert:
+        text: 'Your browser does not support features required for using %{application_name}. Please access %{application_name} using a modern browser.'
+        title: Your browser is not supported!
       default_feedback: Well done. All tests have been passed.
       feedback: Feedback
       file: 'Test File <span class="number">%{number}</span> (<span class="filename">%{filename}</span>)'