redirectUri in checkSession?

we are trying to integrate Auth0 with other pre-existing system and we’d like to implement SSO as well.
The system needs to synchronize it’s internal session with the Auth0 session.
We’ve been thinking that maybe this code would try authenticate against auth0 and we would get a callback, so the legacy system could confirm the referrer being auth0 and validate the session.

const webAuth = new auth0.WebAuth({
		      domain: '',
		      audience: '',
		      scope: 'openid profile',
		      responseType: 'token id_token',
		      responseMode: 'redirectUri',
		      redirectUri: 'http://localhost:8080/legacySystem/auth0callback'

But, the “/legacySystem/auth0callback” endpoint does never get called.

Can we make checkSession to use the callback URL, or is there some other way to initialize a SSO from javascript and obtain a confirmation in backend?
Thank you

As it has been more than a few months since this topic was opened, and there has been no reply or further information provided as to the existence of the issue, we are closing this topic. Please don’t hesitate to create a new topic if this issue is still present, we would be happy to work with you to help find a resolution.