Brython, Python in the browser
I am impressed but I'm also wondering why people try to avoid learning new stuff -- to potential downvoters, no rant intended. I am just surprised how many people try to circumvent JS: Rubyists with Coffee, Closurists with ClosureScript, etc. instead of just using JS directly. I don't believe the main motivation is JS' potential inferiority and that you could employ much better design pattern with languages compiling to JS. Neither, JS' syntax is bad or ugly. I assume that's it's the fear of learning something new, to be again a beginner. JS has its quirks but in general it's a very modern and beautiful language and offering more innovation than traditional scripting languages. And V8 is so blazingly fast that I sometimes think this feels more like C compiled code which would be just another reason rather to switch to JS in the backend.