Minimal and efficient cross-platform file watching library
npm install @teambit/chokidar> Minimal and efficient cross-platform file watching library

Node.js fs.watch:
* Doesn't report filenames on MacOS.
* Doesn't report events at all when using editors like Sublime on MacOS.
* Often reports events twice.
* Emits most changes as rename.
* Does not provide an easy way to recursively watch file trees.
* Does not support recursive watching on Linux.
Node.js fs.watchFile:
* Almost as bad at event handling.
* Also does not provide any recursive watching.
* Results in high CPU utilization.
Chokidar resolves these problems.
Initially made for Brunch (an ultra-swift web app build tool), it is now used in
Microsoft's Visual Studio Code,
gulp,
karma,
PM2,
browserify,
webpack,
BrowserSync,
and many others.
It has proven itself in production environments.
Version 3 is out! Check out our blog post about it: Chokidar 3: How to save 32TB of traffic every week
Chokidar does still rely on the Node.js core fs module, but when usingfs.watch and fs.watchFile for watching, it normalizes the events it
receives, often checking for truth by getting file stats and/or dir contents.
On MacOS, chokidar by default uses a native extension exposing the DarwinFSEvents API. This provides very efficient recursive watching compared with
implementations like kqueue available on most \*nix platforms. Chokidar still
does have to do some work to normalize the events received that way as well.
On most other platforms, the fs.watch-based implementation is the default, which
avoids polling and keeps CPU usage down. Be advised that chokidar will initiate
watchers recursively for everything within scope of the paths that have been
specified, so be judicious about not wasting system resources by watching much
more than needed.
Install with npm:
``sh`
npm install chokidar
Then require and use it in your code:
`javascript
const chokidar = require('chokidar');
// One-liner for current directory
chokidar.watch('.').on('all', (event, path) => {
console.log(event, path);
});
`
`javascript
// Example of a more typical implementation structure
// Initialize watcher.
const watcher = chokidar.watch('file, dir, glob, or array', {
ignored: /(^|[\/\\])\../, // ignore dotfiles
persistent: true
});
// Something to use when events are received.
const log = console.log.bind(console);
// Add event listeners.
watcher
.on('add', path => log(File ${path} has been added))File ${path} has been changed
.on('change', path => log())File ${path} has been removed
.on('unlink', path => log());
// More possible events.
watcher
.on('addDir', path => log(Directory ${path} has been added))Directory ${path} has been removed
.on('unlinkDir', path => log())Watcher error: ${error}
.on('error', error => log())
.on('ready', () => log('Initial scan complete. Ready for changes'))
.on('raw', (event, path, details) => { // internal
log('Raw event info:', event, path, details);
});
// 'add', 'addDir' and 'change' events also receive stat() results as second
// argument when available: https://nodejs.org/api/fs.html#fs_class_fs_stats
watcher.on('change', (path, stats) => {
if (stats) console.log(File ${path} changed size to ${stats.size});
});
// Watch new files.
watcher.add('new-file');
watcher.add(['new-file-2', 'new-file-3', '*/other-file']);
// Get list of actual paths being watched on the filesystem
var watchedPaths = watcher.getWatched();
// Un-watch some files.
await watcher.unwatch('new-file*');
// Stop watching.
// The method is async!
watcher.close().then(() => console.log('closed'));
// Full list of options. See below for descriptions.
// Do not use this example!
chokidar.watch('file', {
persistent: true,
ignored: '*.txt',
ignoreInitial: false,
followSymlinks: true,
cwd: '.',
disableGlobbing: false,
usePolling: false,
interval: 100,
binaryInterval: 300,
alwaysStat: false,
depth: 99,
awaitWriteFinish: {
stabilityThreshold: 2000,
pollInterval: 100
},
ignorePermissionErrors: false,
atomic: true // or a custom 'atomicity delay', in milliseconds (default 100)
});
`
chokidar.watch(paths, [options])
* paths (string or array of strings). Paths to files, dirs to be watched\
recursively, or glob patterns.
- Note: globs must not contain windows separators (),/
because that's how they work by the standard —
you'll need to replace them with forward slashes ().options
- Note 2: for additional glob documentation, check out low-level
library: picomatch.
* (object) Options object as defined below:
#### Persistence
* persistent (default: true). Indicates whether the processfalse
should continue to run as long as files are being watched. If set to when using fsevents to watch, no more events will be emittedready
after , even if the process continues to run.
#### Path filtering
* ignored (anymatch-compatible definition)fs.Stats
Defines files/paths to be ignored. The whole relative or absolute path is
tested, not just filename. If a function with two arguments is provided, it
gets called twice per path - once with a single argument (the path), second
time with two arguments (the path and theignoreInitial
object of that path).
* (default: false). If set to false then add/addDir events are also emitted for matching paths whileready
instantiating the watching as chokidar discovers these file paths (before the event).followSymlinks
* (default: true). When false, only thecwd
symlinks themselves will be watched for changes instead of following
the link references and bubbling events through the link's path.
* (no default). The base directory from which watch paths are to bedisableGlobbing
derived. Paths emitted with events will be relative to this.
* (default: false). If set to true then the strings passed to .watch() and .add() are treated as
literal path names, even if they look like globs.
#### Performance
* usePolling (default: false).false
Whether to use fs.watchFile (backed by polling), or fs.watch. If polling
leads to high CPU utilization, consider setting this to . It istrue
typically necessary to **set this to to successfully watch files overtrue
a network**, and it may be necessary to successfully watch files in other
non-standard situations. Setting to explicitly on MacOS overrides theuseFsEvents default. You may also set the CHOKIDAR_USEPOLLING env variableusePolling: true
to true (1) or false (0) in order to override this option.
* _Polling-specific settings_ (effective when )interval
* (default: 100). Interval of file system polling, in milliseconds. You may alsobinaryInterval
set the CHOKIDAR_INTERVAL env variable to override this option.
* (default: 300). Interval of file systemuseFsEvents
polling for binary files.
(see list of binary extensions)
* (default: true on MacOS). Whether to use thefsevents watching interface if available. When set to true explicitlyfsevents
and is available this supercedes the usePolling setting. Whenfalse
set to on MacOS, usePolling: true becomes the default.alwaysStat
* (default: false). If relying upon thefs.Statsadd
object that may get passed with , addDir, and change events, settrue
this to to ensure it is provided even in cases where it wasn'tdepth
already available from the underlying watch events.
* (default: undefined). If set, limits how many levels ofawaitWriteFinish
subdirectories will be traversed.
* (default: false).add
By default, the event will fire when a file first appears on disk, beforechange
the entire file has been written. Furthermore, in some cases some awaitWriteFinish
events will be emitted while the file is being written. In some cases,
especially when watching for large files there will be a need to wait for the
write operation to finish before responding to a file creation or modification.
Setting to true (or a truthy value) will poll file size,add
holding its and change events until the size does not change for aoptions.awaitWriteFinish
configurable amount of time. The appropriate duration setting is heavily
dependent on the OS and hardware. For accurate detection this parameter should
be relatively high, making file watching much less responsive.
Use with caution.
can be set to an object in order to adjustawaitWriteFinish.stabilityThreshold
timing params:*
* (default: 2000). Amount of time inawaitWriteFinish.pollInterval
milliseconds for a file size to remain constant before emitting its event.
* (default: 100). File size polling interval, in milliseconds.
#### Errors
* ignorePermissionErrors (default: false). Indicates whether to watch filesEPERM
that don't have read permissions if possible. If watching fails due to EACCES
or with this set to true, the errors will be suppressed silently.atomic
* (default: true if useFsEvents and usePolling are false).change
Automatically filters out artifacts that occur when using editors that use
"atomic writes" instead of writing directly to the source file. If a file is
re-added within 100 ms of being deleted, Chokidar emits a eventunlink
rather than then add. If the default of 100 ms does not work wellatomic
for you, you can override it by setting to a custom value, in
milliseconds.
chokidar.watch() produces an instance of FSWatcher. Methods of FSWatcher:
* .add(path / paths): Add files, directories, or glob patterns for tracking..on(event, callback)
Takes an array of strings or just one string.
* : Listen for an FS event.add
Available events: , addDir, change, unlink, unlinkDir, ready,raw, error.all
Additionally is available which gets emitted with the underlying eventready
name and path for every event other than , raw, and error. raw is internal, use it carefully..unwatch(path / paths)
* : Stop watching files, directories, or glob patterns..close()
Takes an array of strings or just one string.
* : async Removes all listeners from watched files. Asynchronous, returns Promise. Use with await to ensure bugs don't happen..getWatched()
* : Returns an object representing all the paths on the fileFSWatcher
system being watched by this instance. The object's keys are all thecwd
directories (using absolute paths unless the option was used), and the
values are arrays of the names of the items contained in each directory.
If you need a CLI interface for your file watching, check out
chokidar-cli, allowing you to
execute a command on each change, or get a stdio stream of change events.
* npm WARN optional dep failed, continuing fsevents@n.n.nnpm
* This message is normal part of how handles optional dependencies and is
not indicative of a problem. Even if accompanied by other related error messages,
Chokidar should function properly.
* TypeError: fsevents is not a constructorrm -rf node_modules package-lock.json yarn.lock && npm install
* Update chokidar by doing , or update your dependency that uses chokidar.
* Chokidar is producing ENOSP error on Linux, like this:bash: cannot set terminal process group (-1): Inappropriate ioctl for device bash: no job control in this shell
* Error: watch /home/ ENOSPC
echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf && sudo sysctl -p
* This means Chokidar ran out of file handles and you'll need to increase their count by executing the following command in Terminal:
For more detailed changelog, see full_changelog.md.
- v3.5 (Jan 6, 2021): Support for ARM Macs with Apple Silicon. Fixes for deleted symlinks.
- v3.4 (Apr 26, 2020): Support for directory-based symlinks. Fixes for macos file replacement.
- v3.3 (Nov 2, 2019): FSWatcher#close() method became async. That fixes IO race conditions related to close method.ignored` option if needed. Improve initial Linux scan time by 50%.
- v3.2 (Oct 1, 2019): Improve Linux RAM usage by 50%. Race condition fixes. Windows glob fixes. Improve stability by using tight range of dependency versions.
- v3.1 (Sep 16, 2019): dotfiles are no longer filtered out by default. Use
- v3 (Apr 30, 2019): massive CPU & RAM consumption improvements; reduces deps / package size by a factor of 17x and bumps Node.js requirement to v8.16 and higher.
- v2 (Dec 29, 2017): Globs are now posix-style-only; without windows support. Tons of bugfixes.
- v1 (Apr 7, 2015): Glob support, symlink support, tons of bugfixes. Node 0.8+ is supported
- v0.1 (Apr 20, 2012): Initial release, extracted from Brunch
Why was chokidar named this way? What's the meaning behind it?
>Chowkidar is a transliteration of a Hindi word meaning 'watchman, gatekeeper', चौकीदार. This ultimately comes from Sanskrit _ चतुष्क_ (crossway, quadrangle, consisting-of-four). This word is also used in other languages like Urdu as (چوکیدار) which is widely used in Pakistan and India.
MIT (c) Paul Miller (