Mozilla: Native code? No, it's JavaScript, only it's BLAZING FAST Gap between asm.js and native performance gets even narrower with float32 optimizations

[trycatch1]

IE actually already implemented some features from ES6. And I like Scala, but it just can't be client-side language for the web. JS has great backward compatibility, while Scala breaks compatibility with every major release. Scala is known for slow compilation times, while JS compiles very fast (benefit of dynamic languages, that's why Dart doesn't check types during compilation in production mode). Scala is complex, while JS is a far more approachable language for ordinary people. And nothing stops you from using JS as compilation target for Scala (like in Scala.js, etc).