Merge branch 'lock-sw' into 'main'

Prevent a new ServiceWorker from being installed after the page loads

See merge request soapbox-pub/soapbox!2862

src/main.tsx

@@ -25,11 +25,12 @@ import './styles/tailwind.css';
 
 import './precheck';
 import ready from './ready';
-import { registerSW } from './utils/sw';
+import { registerSW, lockSW } from './utils/sw';
 
 if (BuildConfig.NODE_ENV === 'production') {
   printConsoleWarning();
   registerSW('/sw.js');
+  lockSW();
 }
 
 ready(() => {

src/utils/sw.ts

@@ -1,9 +1,16 @@
 /** Register the ServiceWorker. */
 function registerSW(path: string) {
   if ('serviceWorker' in navigator) {
-    window.addEventListener('load', () => {
     navigator.serviceWorker.register(path, { scope: '/' });
-    });
+  }
+}
+
+/** Prevent a new ServiceWorker from being installed. */
+function lockSW() {
+  if ('serviceWorker' in navigator) {
+    navigator.serviceWorker.register = () => {
+      throw new Error('ServiceWorker already registered.');
+    };
   }
 }
 
@@ -22,4 +29,5 @@ const unregisterSW = async(): Promise<void> => {
 export {
   registerSW,
   unregisterSW,
+  lockSW,
 };