I'm not sure they meant any language. It sounds like they're advocating for using a non-Java language that compiles to bytecode to be run on the JVM. E.g. Kotli

I'm not sure they meant any language. It sounds like they're advocating for using a non-Java language that compiles to bytecode to be run on the JVM. E.g. Kotlin, Scala, Clojure, Groovy, Jython, JRuby etc. The goal of the JVM is "write once, run anywhere". v8 achieves the same, but for languages that compile to Javascript. E.g. Dart, Elm, Typescript, CoffeeScript, ClojureScript etc. I think the real choice to be made is ecosystem. There are languages to suit every programming style in either camp. The availability and quality of packages in the Java ecosystem is higher IMO (use Spring and it just works). Node has non-blocking I/O by default; it's possible to implement the same in Java, but you have to make a conscious decision to do so. Java has threads, but Node has workers. Java can have a longer startup time and is better suited for servers with high uptime, Node starts up quick and is easier to use in on demand situations etc. I don't really know why you would, but there is RingoJS if you want to run Javascript on the JVM for some reason.