Ask HN: Books for learning formal web dev?

Hi all, I'm very interested in going into frontend/backend Web Development outside of university, but all my Web Development experience is very informal.

When I build sites, I learn as I go; I don't think I could pass a technical interview because I lack formal knowledge of the area. I have always been a C++/application developer for my internships, so Web Development has always been only a hobby of mine.

What sort of books should I read to gain a more formal understanding of Web Development? I know a bit of RoR and mostly code now using Angular2/Nodejs, but figure I should also learn php right?

Thanks for any guidance!