Ich kann Push-Benachrichtigungen senden und im Servicemitarbeiter einen Serviceabruf tätigen. Ich möchte nur die GCM-Registrierungs-ID mit diesem Serviceabruf senden. So erhalten Sie die Registrierungs- oder Abonnement-ID in service worker

hier ist mein Code

self.addEventListener('push', function(event) {
  console.log('Received a push message from local', event);

  var title = 'My title file. Testing on';
  var body = 'New Push Message.';
  var icon = 'refresh_blueicon.png';
  var tag = 'my-push-tag';

  event.waitUntil(
// Here i need to wind GCM Registration id / Subscription id with external service call


  fetch('http://localhost/pushMsg/Push_Notification/msg.php').then(function(response){

     if (response.status !== 200) {
        console.log('Looks like there was a problem. Status Code: ' +
        response.status);
        throw new Error();
      }
       // Examine the text in the response
      return response.json().then(function(data) {

       self.registration.showNotification(data.title, {
          body: data.msg,
          icon: icon,
          tag: tag
        })
  })
  })


  );
});


self.addEventListener('notificationclick', function(event) {
  console.log('On notification click: ', event.notification.tag);
  // Android doesn’t close the notification when you click on it
  // See: http://crbug.com/463146
  event.notification.close();

  // This looks to see if the current is already open and
  // focuses if it is
  event.waitUntil(clients.matchAll({
    type: "window"
  }).then(function(clientList) {
    for (var i = 0; i < clientList.length; i++) {
      var client = clientList[i];
      if (client.url == '/' && 'focus' in client)
        return client.focus();
    }
    if (clients.openWindow)
      return clients.openWindow('/');
  }));

});