But now I do JavaScript + WebGL (which is admittedly slower than both C#, Java and C++): http://clara.io
https://xamarin.com/ imho a much better alternative to C++. I really like C# as a language, it's got that general purpose excellence, but when you get on with things like LINQ,Rx,TPL it's very hard to go back to a language without such first class citizen frameworks.
The only real downsides are scaling issues that npm is running into, the fact that Google moved much of its V8 team to Dart, and no WebGL on iOS.
Node.js is just an implementation of the Reactor pattern with some package management.
Google are smart people, they understand that dynamic weakly typed language is a dead end, hence Dart for client and Go for server.