function onInstall(event) {
  console.log("[Serviceworker]", "Installing!", event);
}

function onActivate(event) {
  console.log("[Serviceworker]", "Activating!", event);
}

function onFetch(event) {
  console.log("[Serviceworker]", "Fetching!", event);
}
self.addEventListener("install", onInstall);
self.addEventListener("activate", onActivate);
self.addEventListener("fetch", onFetch);