if (!('serviceWorker' in navigator)) {
  // Service Worker isn't supported on this browser
  // Disable or hide UI.
  return;
}

if (!('PushManager' in window)) {
  // Push isn't supported on this browser
  // Disable or hide UI.
  return;
}

Notification.requestPermission().then(function(result) {
  if (result === 'denied') {
    console.log('Permission wasn\'t granted');
    return;
  }
  if (result === 'default') {
    console.log('The permission request was dismissed');
    return;
  }
  // Do something with the granted permission
  // result === 'granted' in this case
});

navigator.serviceWorker.register('/service-worker.js')
  .then(function(registration) {
    const subscribeOptions = {
      userVisibleOnly: true,
      applicationServerKey: 'key...'
    };

    return registration.pushManager.subscribe(subscribeOptions);
  })
  .then(function(pushSubscription) {
    console.log(JSON.stringify(pushSubscription));
    return pushSubscription;
  });

self.addEventListener('push', function(event) {

  notification = event.data.json()

  event.waitUntil(
    self.registration.showNotification(
      notification.title, notification.options
    )
  )

})

self.addEventListener('notificationclose', function(event) {
  const dismissedNotification = event.notification

  event.waitUntil( triggerAnalytics( dismissedNotification ) )
})

self.addEventListener('notificationclick', function(event) {
  const clickedNotification = event.notification
  clickedNotification.close()

  event.waitUntil( performAction( clickedNotification ) );
});