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 using

fs.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 Darwin

FSEvents 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:

Then require and use it in your code:

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 (/).

    - Note 2: for additional glob documentation, check out low-level

    library: picomatch.

options (object) Options object as defined below:

persistent (default: true). Indicates whether the process

should continue to run as long as files are being watched. If set to

false when using fsevents to watch, no more events will be emitted

after ready, even if the process continues to run.

ignored (anymatch-compatible definition)

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 the

[fs.Stats](https://nodejs.org/api/fs.html#fs_class_fs_stats)

object of that path).

ignoreInitial (default: false). If set to false then add/addDir events are also emitted for matching paths while

instantiating the watching as chokidar discovers these file paths (before the ready event).

followSymlinks (default: true). When false, only the

symlinks themselves will be watched for changes instead of following

the link references and bubbling events through the link's path.

cwd (no default). The base directory from which watch paths are to be

derived. Paths emitted with events will be relative to this.

disableGlobbing (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.

usePolling (default: false).

Whether to use fs.watchFile (backed by polling), or fs.watch. If polling

leads to high CPU utilization, consider setting this to false. It is

typically necessary to set this to true to successfully watch files over

a network, and it may be necessary to successfully watch files in other

non-standard situations. Setting to true explicitly on MacOS overrides the

useFsEvents default. You may also set the CHOKIDAR_USEPOLLING env variable

to true (1) or false (0) in order to override this option.

_Polling-specific settings_ (effective when usePolling: true)

  interval (default: 100). Interval of file system polling, in milliseconds. You may also

    set the CHOKIDAR_INTERVAL env variable to override this option.

  binaryInterval (default: 300). Interval of file system

  polling for binary files.

  (see list of binary extensions)

useFsEvents (default: true on MacOS). Whether to use the

fsevents watching interface if available. When set to true explicitly

and fsevents is available this supercedes the usePolling setting. When

set to false on MacOS, usePolling: true becomes the default.

alwaysStat (default: false). If relying upon the

[fs.Stats](https://nodejs.org/api/fs.html#fs_class_fs_stats)

object that may get passed with add, addDir, and change events, set

this to true to ensure it is provided even in cases where it wasn't

already available from the underlying watch events.

depth (default: undefined). If set, limits how many levels of

subdirectories will be traversed.

awaitWriteFinish (default: false).

By default, the add event will fire when a file first appears on disk, before

the entire file has been written. Furthermore, in some cases some change

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 awaitWriteFinish to true (or a truthy value) will poll file size,

holding its add and change events until the size does not change for a

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.

  *options.awaitWriteFinish can be set to an object in order to adjust

  timing params:*

  awaitWriteFinish.stabilityThreshold (default: 2000). Amount of time in

  milliseconds for a file size to remain constant before emitting its event.

  awaitWriteFinish.pollInterval (default: 100). File size polling interval, in milliseconds.

ignorePermissionErrors (default: false). Indicates whether to watch files

that don't have read permissions if possible. If watching fails due to EPERM

or EACCES with this set to true, the errors will be suppressed silently.

atomic (default: true if useFsEvents and usePolling are false).

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 change event

rather than unlink then add. If the default of 100 ms does not work well

for you, you can override it by setting atomic 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.

Takes an array of strings or just one string.

.on(event, callback): Listen for an FS event.

Available events: add, addDir, change, unlink, unlinkDir, ready,

raw, error.

Additionally all is available which gets emitted with the underlying event

name and path for every event other than ready, raw, and error.  raw is internal, use it carefully.

.unwatch(path / paths): Stop watching files, directories, or glob patterns.

Takes an array of strings or just one string.

.close(): 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 file

system being watched by this FSWatcher instance. The object's keys are all the

directories (using absolute paths unless the cwd 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.

  This message is normal part of how npm handles optional dependencies and is

    not indicative of a problem. Even if accompanied by other related error messages,

    Chokidar should function properly.

  Update chokidar by doing rm -rf node_modules package-lock.json yarn.lock && npm install, 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

  This means Chokidar ran out of file handles and you'll need to increase their count by executing the following command in Terminal:

  echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf && sudo sysctl -p

For more detailed changelog, see [full_changelog.md](.github/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.

- 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 ignored option if needed. Improve initial Linux scan time by 50%.

- 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.