<script>
async function register(script, scope) {
  const registration = await navigator.serviceWorker.register(
      script, {scope: scope})
  await new Promise(resolve =>
    registration.installing.addEventListener('statechange', resolve));
}
async function initialize() {
  await register('service-worker-prefetch.js', './sw-prefetch-scope/');
  document.title = "Done";
}
initialize();
</script>