Hacker News Reader

That's what Source Maps are for. Currently supported in a superset of {CoffeeScript, TypeScript and GWT}.

Sadly very few browsers support them.

Dart. You debug in Dart and it's (generally) considered a bug if the generated JS deviates in behavior. The JS is rather readable, if needed. It also runs server-side.

Thanks! (and the other guys too, but Dart seems most like what I was looking for ...)

Many of the compilers generate relatively human-readable output JS, so if you know JS, you can debug the output. This is still true for JSIL (albeit less than before... sigh) and is obviously true for languages like TypeScript where the mapping is direct.

Go2js (https://github.com/kless/go2js). Translator from Go which was designed to translate line-to-line, but you should debug on Go since it's much easier.