I need to find a Javascript IDE or editor that can display code hints for external files such as Three.js. Any help would be appreciated.
Disclaimer, I'm the author of the tern.java.
If you use Eclipse, I suggest you that you install tern.java 0.10.0 (not released) which provides a tern support for three.js with completion for three.js :
If you are using other JavaScript Editors like Emacs, Vim, Sublime, you can use the tern plugin tern-threejs