I've been learning frame by frame animation lately and wondered how far one can go thats browser based. Plus I needed some more dev practice for interviews.
This is nice. It's simple, functional, and free of bloat. You should build on this a bit! Maybe add a way to save and load animations to/from indexeddb, or to download them as gifs or sets of PNGs. You could also add a way to change the pen thickness and color.