I followed the SPA Quickstart religiously (Auth0 React SDK Quickstarts: Login) to integrate Auth0 into my React 16.12 app, and everything works fine on the React+Auth0 front. The last step I need to integrate now is to intercept the redirect in order to get the Auth0 access token, send it to my backend to exchange it for a Firebase token (Firebase function call), and then use the Firebase token to open a Firebase session (custom token authentication).
Any idea of how I can do that?