app.js

Notification.requestPermission(result => {
  if (result === 'granted') {

    if ('Notification' in window) {
      navigator.serviceWorker.ready.then(registration => {
        registration.showNotification('Vibration Sample', {
          body: 'Buzz! Buzz!',
          tag: 'vibration-sample'
        });
      });
    }

  }
});