If you're interested in a functional approach to UI code, check out functional reactive programming (FRP). It's a declarative way to specify UI logic which abstracts away much of the inherent messiness of using mutable state and callbacks.

I've played around with FRP in Haskell, and have found it much nicer than the more standard approaches to implementing UI logic. Before using FRP, my main UI experience was with Java Swing and web development, and FRP is definitely a step up. I've found it easier to write the code in the first place and then much easier to add new features and logic.

I've only used FRP with native UIs, but I think it would be very natural for web development as well. It's certainly a shift in philosophy and mindset, but one that I think is well worth overcoming.

Unfortunately, I do not know of a good tutorial for using FRP. I'm sure there are some out there, but I basically picked it up by reading academic papers which are not to everyone's taste. That said, I actually found some of the papers were clearer than the blog posts and SO questions I found online!

I'm probably going to write a basic FRP tutorial in Haskell some time soon, probably built around some very simple application (maybe John Conway's Game of Life). It really is a fun subject. Is anybody interested in something like that?