> If a front-ender on my team started using CoffeeScript on a project I work on, I'd take him to one side and say "it's fine to practice weird kinks in private,

> If a front-ender on my team started using CoffeeScript on a project I work on, I'd take him to one side and say "it's fine to practice weird kinks in private, but compile it into JavaScript before you check it in". :) I know this was just a hypothetical, but this is a bad idea. You've lost the original source code and replaced it with something that is, I think everyone can agree CS-advocates or not, hard-to-read Javascript code.