JS2-mode for Emacs[1][2] does this. It is awesome. [1]: Original version: http://code.google.com/p/js2-mode/ http://code.google.com/p/js2-mode/ [2]: Improved

JS2-mode for Emacs[1][2] does this. It is awesome. [1]: Original version: http://code.google.com/p/js2-mode/ http://code.google.com/p/js2-mode/ [2]: Improved (IMO) fork: https://github.com/mooz/js2-mode https://github.com/mooz/js2-mode Additionally, you can configure JS[HL]int to use flymake[3]. The trick is to improve performance by having it talk to a running JavaScript process (e.g. a node server) instead of starting a new one each time. [3]: http://www.emacswiki.org/emacs/FlymakeJavaScript#toc3 http://www.emacswiki.org/emacs/FlymakeJavaScript#toc3