[jmspring]

So many tool chains and the like depend on being connected. That said, some books (for instance) have the code in place / examples you can downlaod.

If you are up for a new language and since you are front end focused, making sure your system is setup for it, maybe look at learning Rust and the book - https://pragprog.com/titles/hwrust/hands-on-rust/

It builds a game through the process. I found it a fun way to learn the language. But again, I'm not sure how possible it is to do offline.