Relearning JavaScript After Years Away

I wanted to leave myself a note, in hopes that I will find it next time I’m working on this project, that JavaScript has gotten hard. Back when I first started working with it, in 1998 or so, JavaScript/ECMAScript wasn’t that complicated and wasn’t used for that much. I’m confident there were edge cases of people doing really cool stuff with it, but I didn’t know that work or have forgotten it. Most of the cool stuff, it seemed, was in Flash or other media-rich environments.
With this project, however, I’ve provisionally adopted a client interface that’s heavy with the dense JS that’s become all the rage in the last 15 years. It’s dense enough and advanced enough that I can’t hardly follow it, much less hack it to do what I want it to. My use case is that I want to activate an annotation in the IIPImage display frame from a visually adjacent text hyperlink, but so much of what’s happening is on the fly that I can’t seem to make heads or tails of it. Bring back my basic rollovers!