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I've been driven to insanity by node filesystem watcher wrappers. Sane aims to be fast, small, and reliable file system watcher. It does that by:

  • By default stays away from fs polling because it's very slow and cpu intensive
  • Uses by default and sensibly works around the various issues
  • Maintains a consistent API across different platforms
  • Where is not reliable you have the choice of using the following alternatives:


$ npm install sane

How to choose a mode

Don't worry too much about choosing the correct mode upfront because sane maintains the same API across all modes and will be easy to switch.

  • If you're only supporting Linux and OS X, watchman would be the most reliable mode
  • If you're using node > v0.10.0 use the default mode
  • If you're running OS X and you're watching a lot of directories and you're running into, use watchman
  • If you're in an environment where native file system events aren't available (like Vagrant), you should use polling
  • Otherwise, the default mode should work well for you


sane(dir, options)

Watches a directory and all it's descendant directories for changes, deletions, and additions on files and directories.

var watcher = sane('path/to/dir', {glob: ['**/*.js', '**/*.css']});
watcher.on('ready', function () { console.log('ready') });
watcher.on('change', function (filepath, root, stat) { console.log('file changed', filepath); });
watcher.on('add', function (filepath, root, stat) { console.log('file added', filepath); });
watcher.on('delete', function (filepath, root) { console.log('file deleted', filepath); });
// close 


  • glob: a single string glob pattern or an array of them.
  • poll: puts the watcher in polling mode. Under the hood that means fs.watchFile.
  • watchman: makes the watcher use watchman.
  • dot: enables watching files/directories that start with a dot.
  • ignored: a glob, regex, function, or array of any combination.

For the glob pattern documentation, see minimatch. If you choose to use watchman you'll have to install watchman yourself). For the ignored options, see anymatch.

sane.NodeWatcher(dir, options)

The default watcher class. Uses under the hood, and takes the same options as sane(options, dir).

sane.WatchmanWatcher(dir, options)

The watchman watcher class. Takes the same options as sane(options, dir).

sane.PollWatcher(dir, options)

The polling watcher class. Takes the same options as sane(options, dir) with the addition of:

  • interval: indicates how often the files should be polled. (passed to fs.watchFile)


Stops watching.

sane.{Node|Watchman|Poll}Watcher events

Emits the following events:

All events are passed the file/dir path relative to the root directory

  • ready when the program is ready to detect events in the directory
  • change when a file changes
  • add when a file or directory has been added
  • delete when a file or directory has been deleted


This module includes a simple command line interface, which you can install with npm install sane -g.

Usage: sane <command> [] [--glob=<filePattern>] [--poll] [--watchman] [--dot] [--wait=<seconds>]

        A single string glob pattern or an array of them.

    --poll, -p
      Use polling mode.

    --watchman, -w
      Use watchman (if available).

    --dot, -d
      Enables watching files/directories that start with a dot.

        Duration, in seconds, that watching will be disabled
        after running <command>. Setting this option will
        throttle calls to <command> for the specified duration.

It will watch the given directory and run the given every time a file changes.

CLI example usage

  • sane 'echo "A command ran"'
  • sane 'echo "A command ran"' --glob='**/*.css'
  • sane 'echo "A command ran"' site/assets/css --glob='**/*.css'
  • sane 'echo "A command ran"' --wait=3
  • sane 'echo "A command ran"' -p




The CLI was originally based on the watch CLI. Watch is licensed under the Apache License Version 2.0.