I use "SeamlessLoop.js" for loops. https://github.com/Hivenfour/SeamlessLoop
Actually this is not a generator. It is a constructor, it can play 3 samples at the same time.
It takes randomly 3 samples from folder 'wub', 'pluck', 'drums' and play it.
Demo at: https://olegmedv.github.io/Dubstep-Generator-Button/