I sometimes ponder trying something new even though it's crazy to learn during a Ludum Dare. Does anyone have suggestions for a web-capable game framework that is very easy to pick up?

I always do Flash which despite being antiquated, is super easy to get going, and works on most any Windows system. Plus, the FlashDevelop IDE is a joy to use.

I feel like every time I look into a HTML5 / Javascript-ish system, it ends up being super flaky on different browsers, has tearing, has sound problems, or some other issues due to the variety of browser quirks. However, I figured I would ask in case someone can change my mind!