I just posted this in another comment: https://github.com/Juniper/libslax/wiki/Intro

It would at least be an interesting project. If someone put the elbow grease into it it is distinctly possible that an XSLT stylesheet could be not just converted to JS (which is obviously true and just a matter of effort), but converted to something that is at least on the edge of human usable and editable, and some light refactoring away from being decent code.