Much progress has been made since version 2.0. The codebase is becoming more mature. :-)
In version 2.1.1, I added functionality to us HTML5 local storage to remember the estimated number of cores in the CPU between sessions. I also fixed an issue where the selected region is off a little bit to the side.
In version 2.2, I finally added the functionality to select the colors used to draw the fractals.
In version 2.3.0, I added functionality to select the region to zoom in on with touch. It's very nice, but doesn't work in all browsers. In 2.3.2, I use an experimental library to make the program backwards-compatible with MS IE's non-standard "pointer events". I still don't recommend using IE with this program (or any other for that matter!); the Javascript performance is abysmal.
In version 2.3.1, I did a major code clean-up with jslint.
Looking to the future, I want to expand on the functions that the mathematics engine supports. I also intend to add some unit tests. It's tough working on an open-source project on the side!