Does this refer to growth in number of users or in number of modules? Or maybe just counting the number of lines of code?
If I could offer any advice to anyone who is relatively new to all this, I would say choose anything else: Ruby/Rails, PHP/Symfony, Python/Django, Java/Spring, C#/.NET, whatever. You'll be doing yourself a favor. Learn how to do things correctly, in an tech stack that actually exists and works properly and makes sense, then see where things stand for JS on the server in a couple years. The bad habits, mistaken assumptions, and rampant misinformation being spread in the JS world these days is just amazing.
I think another factor is the level of conservatism of the programmer in question: would you rather work on stable but somewhat boring platforms at a large enterprise, or do you want to be on that new-new at a hip startup? (These options obviously exist on a spectrum.)
If you want to be in the fastest-moving, most exciting ecosystem around, it seems to me that JS is the train you want to be on.