Last time I checked, the ability to write Javascript using both languages was of experimental and/or novelty use only (hence the "cupholders").

Facebook uses an OCaml js_of_ocaml-based frontend for a large chunk of their production code editing. Not a great video, but here's the CUFP 2013 talk on the topic: http://www.youtube.com/watch?v=gKWNjFagR9k