CoffeeScriptLineMatcher lets you see CoffeeScript/JavaScript code side by side. It's mostly geared toward debugging, but it also helps you examine the transformations made by the CS transcompiler.

Nice to see this, as it seems to address one of the most common concerns about using CoffeeScript. I have to wonder, though, how many minds will it really change? Maybe a lot, but I'm wondering how this will pan out. I'm guessing some people provide line matching for debugging as a concern but will continue to move the goal posts as this and other barriers are removed.

I feel like that's a pattern I see around here, which is odd because if you'd rather just use javascript that seems totally reasonable without an excuse.

Great.

Based on that, what would be even more useful still is a way to browse my code from a within the editor itself. Something with say line numbers on some left pane synchronized with the corresponding file section on the right pane.

Some editors already provide a similar feature using line numbers from compilers ; that's usefull to fix syntax errors typically.

I just tried this out and the web interface it provides is awful. You're better off opening the .js and .coffee files in vi and finding things manually. The page is twice the width of my browser as I'm looking at it now.