What web development language should I learn in 2020?

I am an old school, old guy. The traditional JavaScript-CSS-HTML base technologies are good enough for the simple things that I do. One can never go wrong by first learning the fundamental technology, and then adding tools and frameworks and other “superchargers” from a position of knowing a bit.

I have to say that there appears to be a wealth of value-add in the JavaScript space… Node, for example, is enough of its own ecology to bid fair for a role as the fundamental technology, relegating JavaScript to being a bit of glue and integration tool.