fix(PWA): sometimes update notification is not triggered

assets/js/pwa/app.js

@@ -3,50 +3,37 @@ layout: compress
 permalink: '/app.js'
 ---
 
-const keyWaiting = 'sw-waiting';
 const $notification = $('#notification');
 const $btnRefresh = $('#notification .toast-body>button');
 
-function skipWating(registration) {
-  registration.waiting.postMessage('SKIP_WAITING');
-  localStorage.removeItem(keyWaiting);
-}
-
 if ('serviceWorker' in navigator) {
   /* Registering Service Worker */
   navigator.serviceWorker.register('{{ "/sw.js" | relative_url }}')
     .then(registration => {
-      if (registration) {
-        registration.addEventListener('updatefound', () => {
-          let serviceWorker = registration.installing;
 
-          serviceWorker.addEventListener('statechange', () => {
-            if (serviceWorker.state === 'installed') {
+      /* in case the user ignores the notification */
+      if (registration.waiting) {
+        $notification.toast('show');
+      }
+
+      registration.addEventListener('updatefound', () => {
+        registration.installing.addEventListener('statechange', () => {
+          if (registration.waiting) {
             if (navigator.serviceWorker.controller) {
               $notification.toast('show');
-                /* in case the user ignores the notification */
-                localStorage.setItem(keyWaiting, true);
             }
           }
         });
       });
 
       $btnRefresh.click(() => {
-          skipWating(registration);
+        if (registration.waiting) {
+          registration.waiting.postMessage('SKIP_WAITING');
+        }
         $notification.toast('hide');
       });
-
-        if (localStorage.getItem(keyWaiting)) {
-          if (registration.waiting) {
-            /* there's a new Service Worker waiting to be activated */
-            $notification.toast('show');
-          } else {
-            /* closed all open pages after receiving notification */
-            localStorage.removeItem(keyWaiting);
     }
-        }
-      }
-    });
+  );
 
   let refreshing = false;