onactivate = function (e) {
  e.waitUntil(
    self.caches.open("default-cache").then(function (cache) {
      var response = new Response("Hi there");
      return cache.put("madeup.txt", response);
    })
  );
};

onfetch = function (e) {
  if (e.request.url.match(/madeup.txt$/)) {
    var p = self.caches.match("madeup.txt", { cacheName: "default-cache" });
    e.respondWith(p);
  }
};