perf: lean bootstrap javascript (#1734)

_javascript/pwa/app.js

@@ -0,0 +1,51 @@
+import { pwa, baseurl } from '../../_config.yml';
+import Toast from 'bootstrap/js/src/toast';
+
+if ('serviceWorker' in navigator) {
+  if (pwa.enabled) {
+    const swUrl = `${baseurl}/sw.min.js`;
+    const notification = document.getElementById('notification');
+    const btnRefresh = notification.querySelector('.toast-body>button');
+    const popupWindow = Toast.getOrCreateInstance(notification);
+
+    navigator.serviceWorker.register(swUrl).then((registration) => {
+      // In case the user ignores the notification
+      if (registration.waiting) {
+        popupWindow.show();
+      }
+
+      registration.addEventListener('updatefound', () => {
+        registration.installing.addEventListener('statechange', () => {
+          if (registration.waiting) {
+            if (navigator.serviceWorker.controller) {
+              popupWindow.show();
+            }
+          }
+        });
+      });
+
+      btnRefresh.addEventListener('click', () => {
+        if (registration.waiting) {
+          registration.waiting.postMessage('SKIP_WAITING');
+        }
+        popupWindow.hide();
+      });
+    });
+
+    let refreshing = false;
+
+    // Detect controller change and refresh all the opened tabs
+    navigator.serviceWorker.addEventListener('controllerchange', () => {
+      if (!refreshing) {
+        window.location.reload();
+        refreshing = true;
+      }
+    });
+  } else {
+    navigator.serviceWorker.getRegistrations().then(function (registrations) {
+      for (let registration of registrations) {
+        registration.unregister();
+      }
+    });
+  }
+}