since JS sucks at math.

Compared to what? I will concede there are other languages with more accurate and versatile math functionality, however if the entire BitShares wallet can be implemented in js I have to ask what type of math problem are you trying to solve that js is not able to handle it?

If the BitShares web-based wallet can manage all the cryptography required for displaying accurate info, seems pretty capable for all but the rarest of problems.