There is a service that allows authentication through oauth2 tokens. I have an application on react and back on flask. Flask simply takes data from the database and returns to the front. To authorize a user, I need to redirect the user to the authorization page, if the authorization is successful, the page will be redirected and the code parameter will appear in the url, which needs to be transferred to the back-up. How it is better to organize at the front. I made for example the Login button, which opens a page with authorization, how can I get this code further and give it to the server. Just never had experience with authorization before.