self.addEventListener('notificationclick', (event) => {
  event.notification.close()
  event.waitUntil((async () => {
    const windows = await clients.matchAll({ type: 'window', includeUncontrolled: true })
    for (const client of windows) {
      if ('focus' in client) return client.focus()
    }
    if (clients.openWindow) return clients.openWindow('/')
  })())
})