Add service worker

ui/package.json

@@ -47,6 +47,7 @@
     "node-fetch": "^2.6.0",
     "prettier": "^2.0.4",
     "reconnecting-websocket": "^4.4.0",
+    "register-service-worker": "^1.7.1",
     "rxjs": "^6.5.5",
     "terser": "^4.6.11",
     "tippy.js": "^6.1.1",

ui/src/service-worker.ts

@@ -0,0 +1,28 @@
+import { register } from 'register-service-worker';
+
+register('/service-worker.js', {
+  registrationOptions: { scope: './' },
+  ready(registration) {
+    console.log('Service worker is active.');
+  },
+  registered(registration) {
+    console.log('Service worker has been registered.');
+  },
+  cached(registration) {
+    console.log('Content has been cached for offline use.');
+  },
+  updatefound(registration) {
+    console.log('New content is downloading.');
+  },
+  updated(registration) {
+    console.log('New content is available; please refresh.');
+  },
+  offline() {
+    console.log(
+      'No internet connection found. App is running in offline mode.'
+    );
+  },
+  error(error) {
+    console.error('Error during service worker registration:', error);
+  },
+});