irregularexp

I choose Rails for fast prototyping, recently Go if I want pure performance that I can't get from caching, and Elixir + Phoenix if I need a good concurrency model and/or high throughput, but don't necessarily care about the microseconds that can be shaved off with Go.

Elixir + Phoenix seems like a better choice if websockets is going to be a core feature, since the BEAM's concurrency model is better and Phoenix's "Channels" abstraction is so solid. I wouldn't think of using Rails for that use case, even with ActionCable in tow, unless it was a minor feature.

A little off-topic, but I figured the people reading the comments here would be the best place to ask. Why use JavaScript on the server at all? I've developed on both the front end and back end, and written non-trivial server-side code in a number of languages, and I don't see any use-case where JavaScript is "best-in-class." It seems like whether you're aiming for ease/speed of prototyping, pure performance, a good concurrency model, or... any other task I can think of, there's a better tool for the job. There seems to be a decent number of people and companies using Node, though, so let me know what I'm missing!