watchpack

Wrapper library for directory and file watching.

Concept

watchpack high level API doesn't map directly to watchers. Instead a three level architecture ensures that for each directory only a single watcher exists.

The high level API requests DirectoryWatchers from a WatcherManager, which ensures that only a single DirectoryWatcher per directory is created.
A user-faced Watcher can be obtained from a DirectoryWatcher and provides a filtered view on the DirectoryWatcher.
Reference-counting is used on the DirectoryWatcher and Watcher to decide when to close them.
The real watchers are created by the DirectoryWatcher.
Files are never watched directly. This should keep the watcher count low.
Watching can be started in the past. This way watching can start after file reading.
Symlinks are not followed, instead the symlink is watched.

API

var Watchpack = require("watchpack");

var wp = new Watchpack({
	// options:
	aggregateTimeout: 1000
	// fire "aggregated" event when after a change for 1000ms no additional change occurred
	// aggregated defaults to undefined, which doesn't fire an "aggregated" event

	poll: true
	// poll: true - use polling with the default interval
	// poll: 10000 - use polling with an interval of 10s
	// poll defaults to undefined, which prefer native watching methods
	// Note: enable polling when watching on a network path
	// When WATCHPACK_POLLING environment variable is set it will override this option
});

// Watchpack.prototype.watch(files: string[], directories: string[], startTime?: number)
wp.watch(listOfFiles, listOfDirectories, Date.now() - 10000);
// starts watching these files and directories
// calling this again will override the files and directories

wp.on("change", function(filePath, mtime) {
	// filePath: the changed file
	// mtime: last modified time for the changed file (null if file was removed)
	// for folders it's a time before that all changes in the directory happened
});

wp.on("aggregated", function(changes, removals) {
	// changes: a Set of all changed files
	// removals: a Set of all removed files
});

// Watchpack.prototype.pause()
wp.pause();
// stops emitting events, but keeps watchers open
// next "watch" call can reuse the watchers

// Watchpack.prototype.close()
wp.close();
// stops emitting events and closes all watchers

// Watchpack.prototype.getTimeInfoEntries()
var fileTimes = wp.getTimeInfoEntries();
// returns a Map with all known time info objects for files and directories
// this include info from files not directly watched
// key: absolute path, value: object with { safeTime, timestamp }
// safeTime: the time before that all changes happened
// timestamp: only for files, the mtime timestamp of the file

// (deprecated)
// Watchpack.prototype.getTimes()
var fileTimes = wp.getTimes();
// returns an object with all known change times for files
// this include timestamps from files not directly watched
// key: absolute path, value: timestamp as number

lazeebee/watchpack

watchpack

Concept

API