[dap]

It's an interesting presentation, but it neglects an obvious solution to the nested callbacks problem, which are the various "async"-like control-flow libraries out there. More importantly, it neglects a critical problem with all of these approaches, which is being able to observe asynchronous state (from a debugger, repl, or whatever) when things go wrong -- when a callback (or event) you expected doesn't fire, or the same one is called (or emitted) early or too many times. IME, these are the really hard problems to debug in async JavaScript, and there are improvements available (I wrote node-vasync for this), but I still wouldn't say it's well solved by any of these approaches.

[craigyk]

Agreed. I think I saw that async in C# has exceptions that behave as one naively expects they should. That would make JS so much more awesome, even with callbacks. The worst part of them isn't the pyramid, IMO, so much as they all the horrible repeated "if error...."