I'm no Javascript advocate, but I just found out that you can use Chrome like that for JS, where I can edit a function, press Ctrl+S, the Chrome REPL will say s

I'm no Javascript advocate, but I just found out that you can use Chrome like that for JS, where I can edit a function, press Ctrl+S, the Chrome REPL will say something like "functions recompiled in 80ms," and then your running app will use that function. I have to say that developing like that is pretty great.