I'm not sure if something exists already, but if not it might make sense to try and write something that created Intellisense type info files from those, as I keep them up to date already for the IDE
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Does this help at all? http://www.espruino.com/Typescript+and+Visual+Studio+Code+IDE
It came up earlier that it might be a bit out of date (and it's for Typescript) but it might be a way to get started.
The Espruino IDE uses Tern's type declaration format for its type info and docs: http://www.espruino.com/json/espruino.json
I'm not sure if something exists already, but if not it might make sense to try and write something that created Intellisense type info files from those, as I keep them up to date already for the IDE