How much JS do you need to be an entry level web developer?

Answer 1

For web developer, there are webpage designer and webapp developer.

Webpage is, it contains frontend only, you design a nice UI.

Webapp is, it contains backend also, setting up server to respond to different request from the frontend.

Here are frontend roadmap and backend roadmap for your reference:

https://github.com/kamranahmedse/developer-roadmap/blob/master/README.md