After learning html,css,JavaScript is it preferable to a framework like bootstrap or learn php?

Answer 1

You should try those, it’s pretty interesting, so far you can start learning a backend with some js framework, there's nothing in wrong in it

Answer 2

if you know and can use quite well some js frameworks like react, vue, angular; you should try spring in java or .net in c# in the backend

Answer 3

No, i don't know any of that.