This is a basic app using React for the frontend and nodejs for the backend. The app demonstrated a healthy process of authentication and authorization and protecting endpoints.
All of the configurations could be found and changed in 'basic-react-and-node-oauth2\client\my-react-client\src\config.js' Pay attention that the configuration file MUST NOT be exposed in the client side!! I did it this way just to ease my work, but all of the configurations of your client, especially the secret MUST NOT be exposed.
Hope it helps.