Dart also works outside of browsers. The standalone VM can be used to write command line tools and web servers. You can interact with native libraries and you can also embed it in other applications. It offers excellent tooling and good performance. It's quite a bit faster than Ruby, Python, or PHP (Hack included).

There is also a second JIT-free VM called "Fletch" in the works which is meant for locked-down environments like iOS or Sony's PS4.