Hi! I built something similar: https://fergonco.org/MusicJargon/. I think you will find it interesting. It compiles to midi, though. Your browser support is quite a feature, indeed.

Had long discussions with my brother (the family musician) on how to encode chords. At some point I even used the actual UTF characters for sharp and bemol and was a total nightmare to write :D

My effort is mostly abandoned (I switched to teach my kids to actually play!). Courage!