node-pathwatcher

Watch files and directories for changes.

[!IMPORTANT] This library is used in Pulsar in several places for compatibility reasons. The nsfw library is more robust and more widely used; it is available in Pulsar via atom.watchPath and is usually a better choice.

If you’re here because you want a general-purpose file-watching library for Node, use nsfw instead.

The purpose of this library’s continued inclusion in Pulsar is to provide the File and Directory classes that have long been available as exports via require('atom').

Installing

npm install pathwatcher

Building

• Clone the repository
• git submodule init && git submodule update
• Run npm install to install the dependencies
• Run npm test to run the specs

Caveats

This module is context-aware and context-safe; it can be used from multiple worker threads in the same process. If you keep a file-watcher active, though, it’ll keep the environment from closing; you must stop all watchers if you want your script or thread to finish.

If you’re using it in an Electron renderer process, you must take extra care in page reloading scenarios. Be sure to use closeAllWatchers well before the page environment is terminated — e.g., by attaching a beforeunload listener.

Using

const PathWatcher = require('pathwatcher');

watch(filename, listener)

Watch for changes on filename, where filename is either a file or a directory. filename must be an absolute path and must exist at the time watch is called.

The listener callback gets two arguments: (event, path). event can be rename, delete or change, and path is the path of the file which triggered the event.

The watcher is not recursive; changes to the contents of subdirectories will not be detected.

Returns an instance of PathWatcher. This instance is useful primarily for the close method that stops the watch operation.

Caveats

• Watching a specific file or directory will not notify you when that file or directory is created, since the file must already exist before you start watching the path.
• When watching a file, event can be any of rename, delete, or change, where change means that the file’s contents changed somehow.
• When watching a directory, event can only be change, and in this context change signifies that one or more of the directory’s children changed (by being renamed, deleted, added, or modified).
• A watched directory will not report when it is renamed or deleted. If you want to detect when a given directory is deleted, watch its parent directory and test for the child directory’s existence when you receive a change event.

PathWatcher::close()

Stop watching for changes on the given PathWatcher.

closeAllWatchers()

Stop watching on all subscribed paths. All existing PathWatcher instances will stop receiving events. Call this if you’re going to end the process; it ensures that your script will exit cleanly.

getWatchedPaths()

Returns an array of strings representing the actual paths that are being watched on disk.

pathwatcher watches directories in all instances, since it’s easy to do so in a cross-platform manner.

File and Directory

These are convenience wrappers around some filesystem operations. They also wrap PathWatcher.watch via their onDidChange (and similar) methods.

Documentation can be found on the Pulsar documentation site:

• File
• Directory