Near complete rewrite of sidebars JS for reliability:

- Refactored as JavaScript classes.

- Everything is now scoped to behaviours without references to instances
  outside of said behaviours; this is primarily achieved by
  instantiating classes and assigning them to a property on elements we
  attach to, and then destroyed when the behaviour detaches.

- Did I mention hella object-oriented?

See: https://github.com/neurocracy/omnipedia/issues/46

Author: Ambient-Impact

javascript/sidebars.elements.js

@@ -10,13 +10,15 @@
 // - 'omnipediaSidebarsMenuClose': will move focus to the menu open control if
 //   sidebars are off-canvas.
 
+AmbientImpact.onGlobals([
+  'ally.query.tabbable',
+], function() {
 AmbientImpact.on([
-  'OmnipediaSiteThemeSidebarsElements',
-  'OmnipediaSiteThemeSidebarsState',
+  'OmnipediaSiteThemeSidebars',
   'pointerFocusHide',
-], function(sidebarsElements, sidebarsState, aiPointerFocusHide, $) {
+], function(sidebars, aiPointerFocusHide, $) {
 AmbientImpact.addComponent('OmnipediaSiteThemeSidebarsFocus', function(
-  sidebarsFocus, $
+  sidebarsFocus, $,
 ) {
 
   'use strict';
@@ -31,47 +33,53 @@ AmbientImpact.addComponent('OmnipediaSiteThemeSidebarsFocus', function(
   this.addBehaviour(
     'OmnipediaSiteThemeSidebarsFocus',
     'omnipedia-site-theme-sidebars-focus',
-    sidebarsElements.getSidebarsBehaviourSelector(),
+    'body',
     function(context, settings) {
 
-      $(this).on(
-        'omnipediaSidebarsMenuOpen.' + eventNamespace,
-      function(event) {
+      $(this).on(`omnipediaSidebarsMenuOpen.${eventNamespace}`, function(
+        event, instance,
+      ) {
 
-        if (sidebarsState.isOffCanvas() === true) {
-
-          aiPointerFocusHide.lock();
-
-          sidebarsElements.getSidebarsContainer().focus();
+        if (instance.isOffCanvas() !== true) {
+          return;
+        }
 
-          aiPointerFocusHide.unlock();
+        aiPointerFocusHide.lock();
 
-        }
+        $(ally.query.tabbable({
+          context:        instance.$sidebars,
+          includeContext: true,
+        })).first().focus();
 
-      }).on('omnipediaSidebarsMenuClose.' + eventNamespace, function(event) {
+        aiPointerFocusHide.unlock();
 
-        if (sidebarsState.isOffCanvas() === true) {
+      }).on(`omnipediaSidebarsMenuClose.${eventNamespace}`, function(
+        event, instance,
+      ) {
 
-          aiPointerFocusHide.lock();
+        if (instance.isOffCanvas() !== true) {
+          return;
+        }
 
-          sidebarsElements.getSidebarsMenuOpen().focus();
+        aiPointerFocusHide.lock();
 
-          aiPointerFocusHide.unlock();
+        instance.$menuOpen.focus();
 
-        }
+        aiPointerFocusHide.unlock();
 
       });
 
     },
     function(context, settings, trigger) {
 
       $(this).off([
-        'omnipediaSidebarsMenuOpen.'  + eventNamespace,
-        'omnipediaSidebarsMenuClose.' + eventNamespace,
+        `omnipediaSidebarsMenuOpen.${eventNamespace}`,
+        `omnipediaSidebarsMenuClose.${eventNamespace}`,
       ].join(' '));
 
     }
   );
 
 });
 });
+});