Javascript - Decision made

In my day-to-day role I tinker with various languages across a broad range of projects but you know what they say about being a Jack of all trades but a master of none? I figure that I need to focus on one to really go deep and properly learn, but I keep flopping around when trying to decide which. I considered Python as a totally new experience but I've actually just had a brainwave and decided I'll concentrate on JS. It's used for so much now that it really is an obvious place to start. I also use it a lot so this has to be a good place to start.  Maybe 🤷‍♂️