Javascript is used everywhere, yes, but you definitely should spread your focus to other languages as a student. At minimum definitely dig into C for low level understanding and rigor, and a “real language” like C# for exposure to all the great features and paradigms in that world.

It’s fun. There are two angles you can come at how lightsabers work from: how they work in the Star Wars fictional universe, and how something like that might work in our universe. The former builds out the fictional universe into something more “reasonable” in the sense that you can reason within the internal rules of the fiction. Reasoning about fictional worlds, especially with other people, is very fun (see D&D, or religion). The latter is a fun scientific diversion that could even lead to real inventions.