Unless you're interested in mobile app development, js can do anything for you. For frontend there's regular is, for backend there's node.js
You can make desktop apps using node.js and it's module named
So yeah, it's pretty useful and easy to learn. But again, it's not the best but really easy to get started with. And also gives a quality good enough for production works.
Again, it can't help you make apps for mobile but it also comes with a lot of packages for you to be able to do anything very easily at
npm which is the official package manager for node.js