How to check that the administrator is logged in to the react application (firebase)?

Question

User identification

You will need to make an admin panel for the food ordering application. Since there is no experience in developing client-server applications, but there is experience of at least some kind of client development, I chose firebase as a database and implementation of authorization. Just user identification is clear how to do it. Check if there is a user in the store, and if there is, then let it go through the route. But how to make it possible to check a specific user is not clear. It's just that in the code on the client, checking the login password in the open is somehow not right, sort of.
Tell me how to implement access in certain ways, only for specific users, for example, for one administrator.

Answer 1

But how to make it possible to check a specific user is not clear.

- Coincidentally. We run through the users, we find a match by the login entered and the login in the store. Another condition inside the former one is whether the password entered matches the password of that user. If yes, then push the desired route into the history