How is backend and frontend (routing) separated?

Question

Backend

The question, I suppose, is very easy, but unfortunately I did not google the answer myself ...
I have an api and it is available at the url domain.example/api/.........
All other urls must be processed by the front
How to do so that the front router and the back router do not intersect? After all, it turns out that each request to the server is backed up.
Thanks in advance :) And sorry for the stupid question.

Answer 1

Give to any request other than /api the index.html file of your application.
Well, the application will figure out which page to render with its router.