In a similar vein, create your own Hatsune Miku style music https://aidn.jp/mikutap/

Code from main.js: https://www.patatap.com/src/main.js

Enjoyed playing with it. It would be nice to see some WebMIDI support so it can be triggered with a MIDI keyboard.

On the same topic, I found Google's Oboe project really interesting. It's a C++ library for audio that works on both Chrome (via WASM) and Android (with AAudio). This talk from Google I/O 2019 gave a demo/walkthrough: https://www.youtube.com/watch?v=-GaD0RCp-Q0

I use this (and the sister web app typeatap) with my pre-school niece. She loves composing music from keyboard letters and has really learned where the letters are on a qwerty keyboard faster than any other option for someone that age. There is seriously some untapped educational potential here. Or maybe it's just forming bad habits.

Needs a seizure warning. Other than that, it's a lot of fun.

Finally, programmers will be able to show non-technical people how programs are created, haha

it's too bad you can't loop things together