Folder structure for a Node.js project

Concerning the folders you mentioned:

• /libs is usually used for custom classes/functions/modules
• /vendor or /support contains 3rd party libraries (added as git sub-module when using git as source control)
• /spec contains specifications for BDD tests.
• /tests contains the unit-tests for an application (using a testing framework, see here)

NOTE: both /vendor and /support are deprecated since NPM introduced a clean package management. It's recommended to handle all 3rd-party dependencies using NPM and a package.json file

When building a rather large application, I recommend the following additional folders (especially if you are using some kind of MVC- / ORM-Framework like express or mongoose):

• /models contains all your ORM models (called Schemas in mongoose)
• /views contains your view-templates (using any templating language supported in express)
• /public contains all static content (images, style-sheets, client-side JavaScript)
  • /assets/images contains image files
  • /assets/pdf contains static pdf files
  • /css contains style sheets (or compiled output by a css engine)
  • /js contains client side JavaScript
• /controllers contain all your express routes, separated by module/area of your application (note: when using the bootstrapping functionality of express, this folder is called /routes)

I got used to organize my projects this way and i think it works out pretty well.

Update for CoffeeScript-based Express applications (using connect-assets):

• /app contains your compiled JavaScript
• /assets/ contains all client-side assets that require compilation
  • /assets/js contains your client-side CoffeeScript files
  • /assets/css contains all your LESS/Stylus style-sheets
• /public/(js|css|img) contains your static files that are not handled by any compilers
• /src contains all your server-side specific CoffeeScript files
• /test contains all unit testing scripts (implemented using a testing-framework of your choice)
• /views contains all your express views (be it jade, ejs or any other templating engine)

There is a discussion on GitHub because of a question similar to this one: https://gist.github.com/1398757

You can use other projects for guidance, search in GitHub for:

• ThreeNodes.js - in my opinion, seems to have a specific structure not suitable for every project;
• lighter - an more simple structure, but lacks a bit of organization;

And finally, in a book (http://shop.oreilly.com/product/0636920025344.do) suggests this structure:

• index.html
• js/
  • main.js
  • models/
  • views/
  • collections/
  • templates/
  • libs/
    • backbone/
    • underscore/
    • ...
• css/
• ...