I just got a newsletter from Pragmatic Bookshelf with some books that look interesting:
- Rediscovering JavaScript: Master ES6, ES7, and ES8 by Venkat Subramaniam
- Learn Functional Programming with Elixir by Ulisses Almeida
- Rails 5 Test Prescriptions by Noel Rappin*
- Reactive Programming with RxJS 5: Untangle Your Asynchronous JavaScript Code by Sergi Mansilla
(* also related to Rails testing: betterspecs.org)