308 lines
14 KiB
Markdown
308 lines
14 KiB
Markdown
# Chokidar [](https://github.com/paulmillr/chokidar) [](https://github.com/paulmillr/chokidar)
|
|
|
|
> Minimal and efficient cross-platform file watching library
|
|
|
|
[](https://www.npmjs.com/package/chokidar)
|
|
|
|
## Why?
|
|
|
|
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](https://brunch.io/)** (an ultra-swift web app build tool), it is now used in
|
|
[Microsoft's Visual Studio Code](https://github.com/microsoft/vscode),
|
|
[gulp](https://github.com/gulpjs/gulp/),
|
|
[karma](https://karma-runner.github.io/),
|
|
[PM2](https://github.com/Unitech/PM2),
|
|
[browserify](http://browserify.org/),
|
|
[webpack](https://webpack.github.io/),
|
|
[BrowserSync](https://www.browsersync.io/),
|
|
and [many others](https://www.npmjs.com/browse/depended/chokidar).
|
|
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](https://paulmillr.com/posts/chokidar-3-save-32tb-of-traffic/)
|
|
|
|
## How?
|
|
|
|
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.
|
|
|
|
## Getting started
|
|
|
|
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);
|
|
});
|
|
```
|
|
|
|
## API
|
|
|
|
```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`))
|
|
.on('change', path => log(`File ${path} has been changed`))
|
|
.on('unlink', path => log(`File ${path} has been removed`));
|
|
|
|
// More possible events.
|
|
watcher
|
|
.on('addDir', path => log(`Directory ${path} has been added`))
|
|
.on('unlinkDir', path => log(`Directory ${path} has been removed`))
|
|
.on('error', error => log(`Watcher error: ${error}`))
|
|
.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 (`/`).
|
|
- Note 2: for additional glob documentation, check out low-level
|
|
library: [picomatch](https://github.com/micromatch/picomatch).
|
|
* `options` (object) Options object as defined below:
|
|
|
|
#### Persistence
|
|
|
|
* `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.
|
|
|
|
#### Path filtering
|
|
|
|
* `ignored` ([anymatch](https://github.com/es128/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.
|
|
|
|
#### Performance
|
|
|
|
* `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](https://github.com/sindresorhus/binary-extensions/blob/master/binary-extensions.json))
|
|
* `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.
|
|
|
|
#### Errors
|
|
|
|
* `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.
|
|
|
|
### Methods & Events
|
|
|
|
`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.
|
|
|
|
## CLI
|
|
|
|
If you need a CLI interface for your file watching, check out
|
|
[chokidar-cli](https://github.com/open-cli-tools/chokidar-cli), allowing you to
|
|
execute a command on each change, or get a stdio stream of change events.
|
|
|
|
## Install Troubleshooting
|
|
|
|
* `npm WARN optional dep failed, continuing fsevents@n.n.n`
|
|
* 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.
|
|
|
|
* `TypeError: fsevents is not a constructor`
|
|
* 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`
|
|
|
|
## Changelog
|
|
|
|
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](https://github.com/brunch/brunch/blob/9847a065aea300da99bd0753f90354cde9de1261/src/helpers.coffee#L66)
|
|
|
|
## Also
|
|
|
|
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.
|
|
|
|
## License
|
|
|
|
MIT (c) Paul Miller (<https://paulmillr.com>), see [LICENSE](LICENSE) file.
|