As far as I'm concerned, it already exists in two forms:

1. https://try.pandoc.org/

2. http://markup.rocks/

(1) isn’t client-side.

> $.getJSON("/cgi-bin/trypandoc", { from: from, to: to, text: text },

Are those sites using Emscripten or just passing your docs to a server to process?

Markup.rocks says it is client side and appears to be using ghcjs: https://github.com/osener/markup.rocks/blob/master/Makefile#...

Cool! Right now I run a docker container with pandoc on heroku in order to do stuff like make decent PDFs from my iPad... hmm...