[Question]: How can I set the externalId when subscribing a new user.

[PWRM]

How can we help?

How can I set the externalId when subscribing to a new user? According to some research I did, I have to install an Eventhandler. In the handler I can get the userID and attach my own externalId, and set it. If I cannot set the externalId, that's fine, but then I need to know the OneSignal_ID, so I can send future Push messages to a single user. Seems to me the OneSignal_ID should be provided by the change Event.

Tried many setups, with await and without, but the event is never called. According to the documentation this should be the initialisation:

<script src="https://cdn.onesignal.com/sdks/web/v16/OneSignalSDK.page.js" defer></script>
<script>
  window.OneSignalDeferred = window.OneSignalDeferred || [];
  OneSignalDeferred.push(async function(OneSignal) {
    await OneSignal.init({
      appId: <MYAPPID>,
            notifyButton: {
                enable: true
            }
    });
  });
OneSignalDeferred.push(function() {
  OneSignal.User.addEventListener('change', function (event) {
    console.log('change', { event });
  });
});

</script>

Why is the change Event not called?