I'm just about to make something similar! Every Saturday, I teach a class of 10-18 kids aged 10-15. Because the younger ones do not have the patience for more conventional methods(Some refuse to read anything longer than a tweet...), I prepare a .pdf more focused on younger people, here's my most recent one. What do you think? Anyway, it takes about 40 minutes to make a page, so my plan is to either make a text editor or a plugin for an IDE/text editor that acts kind of like genius.com, but for code. I would write code, and then annotate it with descriptions so that when you hover over the code, it's description would display. And some other things like a mode that shows you the order that each statement is read in, to help explain functions, though I'm not sure how plausible that is without writing my own JavaScript interpreter.