Js2-mode

js2-mode provides Emacs font-lock, indentation, and navigation for the JavaScript programming language. It also features an advanced JavaScript parser.

js2-mode

Description	major mode for JavaScript programming
Author	Steve Yegge
Maintainer	FSF
Source	http://bzr.savannah.gnu.org/lh/emacs/elpa/annotate/head:/packages/js2-mode/js2-mode.el
Part of Emacs	no

The original repository (at Google Code) seems to be outdated and https://github.com/mooz/js2-mode#readme seems to be a maintained fork. It includes several changes.

Basic setup

(package-install "js2-mode")
(require 'js2-mode)

Features

• accurate syntax highlighting using a recursive-descent parser
• on-the-fly reporting of syntax errors and strict-mode warnings
• undeclared-variable warnings using a configurable externs framework
• "bouncing" line indentation to choose among alternate indentation points
• smart line-wrapping within comments and strings
• code folding:
  • show some or all function bodies as {...}
  • show some or all block comments as /*...*/
• context-sensitive menu bar and popup menus
• code browsing using the Imenu package
• many customization options
• strict recognition of the Ecma-262 language standard
• support for most Rhino and SpiderMonkey extensions from 1.5 and up
• parsing support for ECMAScript for XML (E4X, ECMA-357)

See Also

• js2-refactor - A refactoring library based on js2-mode.
• Swank-js (homepage) - A REPL to interact with the browser.