I have been using TypeScript. The TypeScript compiler gives me roughly 1-2 second builds, even on a large project that (it can watch code and build incrementall

I have been using TypeScript. The TypeScript compiler gives me roughly 1-2 second builds, even on a large project that (it can watch code and build incrementally). So I get the benefits of static types, plus the benefits of fast iteration, PLUS the benefits of a fully dynamic language for when I want to accomplish something quickly. It's a full win-win-win. Throw in linting to avoid the legacy JavaScript crap and it's pretty awesome.