> Previously, this might have taken me weeks. With JavaScript, I built the prototype in hours.
I really like web/html/javascript for building UIs for this reason. It's really fast to prototype and get something decent looking/working, it has a very fast edit-compile-run loop (if you don't use any fancy tooling, as fast as you can press CTRL-S, Alt-Tab, F5), great debugging tools, and in the end, your product immediately works cross platform, both on desktop and mobile!