[uglycoyote]

Very cool. I've also had a side-project developing something similar for a while: http://sonicpines.com/fretboard

I keep being surprised at people having the same idea e.g., see also Grunfy's post from a few months ago. https://news.ycombinator.com/item?id=17272516 He has some very nice stuff there.

My work-in-progress is also derived from "first principles", although I haven't bothered to try adding alternate tunings yet.

Mostly my focus has been on using it to aid learning improvisation, so one feature i added to my little app was the ability to set up a particular chord pattern on the fretboard and "save" it, so that you can have several different diagrams on the screen at once, e.g., one for each of the three chords in a 3-chord song.

Like you, I also have been using Typescript and SVG, but not D3 (just drawing SVG elements directly using React seems to work well enough for my purposes)