self.addEventListener('fetch', e => {
if (e.request.url.indexOf("?respond-from-service-worker") !== -1) {
e.respondWith(fetch(e.request));
}
});
self.addEventListener('install', event => {
event.waitUntil(self.skipWaiting());
});
self.addEventListener('activate', event => {
event.waitUntil(self.clients.claim());
});