The built-in js-mode in Emacs does not provide many features for working with js framework beside js editing and syntax highlighting. The tips in this post will help you transform your Emacs into a powerful Javascript IDE.

Beautify, unpack or deobfuscate JavaScript and HTML, make JSON/JSONP readable, etc.

All of the source code is completely free and open, available on GitHub under MIT licence,
and we have a command-line version, python library and a node package as well.

web-beautify is a formatting package of HTML, CSS and JavaScript/JSON for Emacs. It uses the command-line/node.js javascript formatter from http://jsbeautifier.org/ to format whole html, css, js or json files, or region.

Beautify HTML, CSS, JavaScript, PHP, Python, Ruby, Java, C, C++, C#, Objective-C, CoffeeScript, TypeScript, Coldfusion, and SQL in Atom