Use Facebook authentication to return user specific pages from my api


I’m adding log in with facebook to my ionic2 app as the only login method. So facebook will handle the authentication, but I’m confused how to handle the authorisation to user specific pages.

At the moment I have a node/express backend to return json for such pages with no auth. How can I handle returning user data from my custom APIs using the facebook auth method?

For example when the user logs in and asks for a private page, say orders, will the client talk just between itself and node - or will it need to go out to facebook again?