It's all depend on what you want to build, JS is like a swiss knife it can be use anywhere, handy, and a must have for web dev, JS excel with many small not too heavy process, that i can say (perhaps, JS always evolve, there are always new JS framework and library everytime i blink FFS)
Other language are also great but you'll need to test it yourself to determined if it the right tool for the job, so you need to know advantages and disadvantages of those tech, no need to learn it just yet but enough to know what they are capable of so you can decide if you want to invest you time to learn them.
in the real live tho you'll want to stick with the one that the market want, but yeah JS is kinda a safe spot but remember safe spot always have many competitor.