Build frontend from scratch for full API Rest

Hello,

I am looking for a tutorial on how to cleanly create a frontend for a web application (with authentication) in full Rest API.

Before learning React or Vue, I would like to create this frontend "from scratch" to better understand these frameworks later. I'm thinking of using simple ajax requests, but I would like to know if there is a better way to do it? (for instance: with routes in frontend, etc.)

Thank you very much.