[skybrian]

The language still matters, but indirectly, because it constrains which frameworks can easily be built. It's doubtful that jQuery and React would have been invented using Java. Even JavaScript is nicer with a language extension (JSX).

[kuschku]

The thing is, Java has (with some tricks) a fully pluggable compiler. And even without tricks, compile time processing is possible.

But Java is "uncool". That’s the big issue.

[skybrian]

The issue is that if you want to do template-like things using language constructs (internal DSL), the syntax is quite limiting.

There are tricks using annotations and strings, and Java 8's lambda expressions do help. But it's still awkward to define a React-like mini-language within Java.

[kuschku]

Well, anything that is a valid syntax can then be modified by the annotation processor.

Add the fact that you can do blocks, and label blocks, and you can do practically s-expressions.