Sorry for the delayed response. Spent all day yesterday responding to feedback. The reason this crashes is due to the internal javascript engine.

In order to ensure that my engine (I simulate a kind of NFA) matches what javascript's engine matches, every time I match on my engine, I also try to exact match using javascript's engine. Unfortunately, javascript's engine always uses backtracking, even when it doesn't need to. Obviously this code should have been turned off for production, and I'll fix it on the next push.

To replicate the crash on your own, try typing: 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab'.match(/^(a)$/) in your console.