js2 mode, especially mooz's fork, is really, really awesome! Another minor-mode to consider is js2-refactor[1], which leverages js2 mode to make refactoring JavaScript code easier on Emacs.
I haven't used it myself because I haven't done any JavaScript since finding out about it, but it seems like a brilliant addition to the already superb Emacs JavaScript experience.
You can also set up flymake mode with JSHint[2] to get style tips and warnings in your buffer[3]. JSHint is like JSLint but more configurable.
[1]: https://github.com/magnars/js2-refactor.el
I haven't used it myself because I haven't done any JavaScript since finding out about it, but it seems like a brilliant addition to the already superb Emacs JavaScript experience.
You can also set up flymake mode with JSHint[2] to get style tips and warnings in your buffer[3]. JSHint is like JSLint but more configurable.
[2]: http://www.jshint.com/
[3]: https://github.com/daleharvey/jshint-mode