Thanks to JSweet, you can now play with React.js in Java.
> git clone https://github.com/cincheo/jsweet-examples-react.git
> cd jsweet-examples-react
> mvn generate-sources
> firefox webapp/<example-name>.html
java -version
in a console to make sure that you have a >= 1.8 JDK.node
and npm
executables must be in the path (https://nodejs.org).