I made this program that shows off the tone.js library: https://www.khanacademy.org/computer-programming/tonejs-midi-player/6639166447468544

Basically, tone.js allows you to make music using Web Audio. Problem is, I can't tell if it's referring to the Oscillator that's allowed according to the guidelines, or if it's using disallowed functionality. I searched the source code and found several references to what could be the oscillator, but I just wanted to be safe.