fb-watchman

fb-watchman is a filesystem watcher that uses the
Watchman file watching service from
Facebook.

Watchman provides file change notification services using very
efficient recursive watches and also allows more advanced change matching and
filesystem tree querying operations using
a powerful expression syntax.

Install

You should [install Watchman](
https://facebook.github.io/watchman/docs/install.html) to make the most of this
module.

Then simply:

$ npm install fb-watchman

Key Concepts

• Watchman recursively watches directories.
• Each watched directory is called a root.
• You must initiate a watch on a root using the watch-project command prior to subscribing to changes
• Rather than separately watching many sibling directories, watch-project consolidates and re-uses existing watches relative to a project root (the location of your .watchmanconfig or source control repository root)
• change notifications are relative to the project root

How do I use it?

Read the NodeJS watchman documentation