It has: https://facebook.github.io/jsx/

Emphasis on "implemented" haha. At least this makes it more open since someone can come in and make their own implementation. As it currently stands I don't think you can use Facebook's implementation to transform JSX to a framework-agnostic object.

You can use babel. Look at the custom example here: http://babeljs.io/docs/advanced/transformers/other/react/

Well, you could fork it:

https://github.com/insin/msx

There are alternatives though, like JSX implemented in sweet.js: http://jlongster.com/Compiling-JSX-with-Sweet.js-using-Readt...

There are babel transforms for it: https://github.com/openjsx In fact I've seen a user use JSX-to-HTML for his Vue templates.