What would you or others recommend to fellow dinosaurs wanting to come to grips with modern JS? The first time I learned it was back in the days when it was ma

What would you or others recommend to fellow dinosaurs wanting to come to grips with modern JS? The first time I learned it was back in the days when it was mainly for mouse rollovers. I want to tackle it as if it were a different language these days (which in many ways it is). But in years past I've been put off by what seemed like high volatility in the current best practices, to the point of flavor-of-the-month syndrome. I'm sure there must be a stable core that's worth learning and using, but as an outsider I have trouble spotting it.