It's worth noting how Node.js goes about resolving a particular required module. For example, if a file /home/tony/projects/foo.js has a require call require('bar'), Node.js scans the filesystem for node_modules in the following order. The first bar.js that is found is returned:

• /home/tony/projects/node_modules/bar.js
• /home/tony/node_modules/bar.js
• /home/node_module/bar.js
• /node_modules/bar.js

Node.js looks for node_moduels/bar in the current folder followed by every parent folder until it reaches the root of the filesystem tree for the current file.