About me Backend developer. 3+ years working with Scala. Work at Zalando in Helsinki (https://tech.zalando.de/). Contact: @ivan0yu at Twitter | https://ivanyu.me/
General purpose language. Runs on JVM (and JS). Multi-paradigm: object-oriented + functional. Mature (first release in 2004). Widely adopted now (Twitter, Apple, Foursquare, Coursera, LinkedIn, Meetup.com, Airbnb, Zalando, SoundCloud, Morgan Stanley, Sberbank, Tinkoff Bank, Raiffeisen bank, QIWI, etc.) Lightbend and Scala Center (EPFL). Scala scala-lang.org
What is great about Scala Strong and powerful type system (safer applications) + type inference. Powerful syntax + macroses - less code a DSLs. Concurrent programming - futures, actors, etc. Functional programming (not mandatory). Good standard library + all the JVM world via interop. Easy programming with immutable values (including collections).
What can make you sad With great power comes great responsibility! Too easy to write complex code. Slow compilation Will be fixed in the next major release (see dotty).
How it works Translates your Scala code into JavaScript. You can use most of Scala and Java standard libraries. Plus specially prepared Scala libraries (rebuilt with Scala.js). Plus JavaScript interop (including type-safe facades). Google Closure compiler for optimization/minification. 150-400 Kb of constant overhead (but remember that you won’t need some additional JS libraries you normally use, e.g. lodash, immutable.js).
Where to continue Official site: https://www.scala-js.org/ Tutorials: https://www.scala-js.org/tutorial/ A book: http://www.lihaoyi.com/hands-on-scala-js/ TodoMVC: http://todomvc.com/examples/scalajs-react/ Lots of presentations & success stories: https://www.scala-js.org/community/