threema-web/public/service-worker.js

// service worker for PWA (progressive web app)

self.addEventListener('install', (event) => {
    // console.log('👷', 'install', event);
    self.skipWaiting();
});

self.addEventListener('activate', (event) => {
    // console.log('👷', 'activate', event);
    return self.clients.claim();
});

self.addEventListener('fetch', function (event) {
    // console.log('👷', 'fetch', event);
    event.respondWith(fetch(event.request));
});