This is Tern. Tern is a stand-alone, editor-independent JavaScript analyzer that can be used to improve the JavaScript integration of existing editors.
Thanks to a group of generous crowd funders, Tern is open-source software, under an MIT license.
There are currently plugins available for Emacs (and Emacs company-mode), Vim, Sublime Text, Eclipse (and general Java API), Light Table, Atom, TextMate and gedit, and built-in support in Brackets, Edge Code, CodeLite, and vy.
For further documentation, see the project page and the manual. To report issues, use the issue tracker. For questions and documentation, see the discussion forum.