Hi, which browser would that be? It has been tested against Chrome, Firefox, and Safari, though there are some weird edge cases (input handling does mouse or touchscreen but not both at the same time; audio needs the buttons toggled to work on iOS; looping music uses a buffer too big for Android Firefox).
I'm looking at migrating the rendering to WebGL to better run on cheap Android devices. Not using any sort of framework has been (and at this rate will continue to be) a learning experience, albeit not one I'm ready to repeat anytime soon.