Squishy's Piano Roll

Question, is Squishy's Piano Roll allowed?

I'm currently trying to make a sheet music editor version of it.

I used it plenty of times and I remember it even being guardian approved at one point. 

From what I see, it uses the AudioContext API (and sneakily `eval`).

Base code that will be used:

https://www.khanacademy.org/computer-programming/music-wip/6280170504241152