hide the version check image if internet connection is broken

app/assets/javascripts/dispatcher.js.es6

@@ -261,6 +261,9 @@
         case 'projects:artifacts:browse':
           new BuildArtifacts();
           break;
+        case 'help:index':
+          gl.VersionCheckImage.bindErrorEvent($('img.js-version-status-badge'));
+          break;
         case 'search:show':
           new Search();
           break;

app/assets/javascripts/version_check_image.js.es6

@@ -0,0 +1,10 @@
+(() => {
+  class VersionCheckImage {
+    static bindErrorEvent(imageElement) {
+      imageElement.off('error').on('error', () => imageElement.hide());
+    }
+  }
+
+  window.gl = window.gl || {};
+  gl.VersionCheckImage = VersionCheckImage;
+})();

app/helpers/version_check_helper.rb

@@ -1,7 +1,8 @@
 module VersionCheckHelper
   def version_status_badge
     if Rails.env.production? && current_application_settings.version_check_enabled
-      image_tag VersionCheck.new.url
+      image_url = VersionCheck.new.url
+      image_tag image_url, class: 'js-version-status-badge'
     end
   end
 end

changelogs/unreleased/broken_iamge_when_doing_offline_update_check-help_page-.yml

@@ -0,0 +1,4 @@
+---
+title: Hide version check image if there is no internet connection
+merge_request: 8355
+author: Ken Ding