watch

external fun watch(filename: PathLike, options: WatchBufferOptions, listener: WatchListener<Buffer> = definedExternally): FSWatcher(source)
external fun watch(filename: PathLike, options: String, listener: WatchListener<Buffer> = definedExternally): FSWatcher(source)

Watch for changes on filename, where filename is either a file or a directory.

The second argument is optional. If options is provided as a string, it specifies the encoding. Otherwise options should be passed as an object.

The listener callback gets two arguments (eventType, filename). eventTypeis either 'rename' or 'change', and filename is the name of the file which triggered the event.

On most platforms, 'rename' is emitted whenever a filename appears or disappears in the directory.

The listener callback is attached to the 'change' event fired by fs.FSWatcher, but it is not the same thing as the 'change' value of eventType.

If a signal is passed, aborting the corresponding AbortController will close the returned fs.FSWatcher.

Since

v0.5.10

Parameters

listener

external fun watch(filename: PathLike, options: WatchOptions? = definedExternally, listener: WatchListener<String> = definedExternally): FSWatcher(source)
external fun watch(filename: PathLike, options: BufferEncoding? = definedExternally, listener: WatchListener<String> = definedExternally): FSWatcher(source)
external fun watch(filename: PathLike, options: WatchOptions, listener: WatchListener<Any> = definedExternally): FSWatcher(source)
external fun watch(filename: PathLike, options: String, listener: WatchListener<Any> = definedExternally): FSWatcher(source)
external fun watch(filename: PathLike, options: WatchOptions = definedExternally): AsyncIterable<FileChangeInfo<String>>(source)
external fun watch(filename: PathLike, options: BufferEncoding = definedExternally): AsyncIterable<FileChangeInfo<String>>(source)
external fun watch(filename: PathLike, options: String): Any(source)

Watch for changes on filename, where filename is either a file or a directory, returning an FSWatcher.

Parameters

filename

A path to a file or directory. If a URL is provided, it must use the file: protocol.

options

Either the encoding for the filename provided to the listener, or an object optionally specifying encoding, persistent, and recursive options. If encoding is not supplied, the default of 'utf8' is used. If persistent is not supplied, the default of true is used. If recursive is not supplied, the default of false is used.


external fun watch(filename: PathLike, listener: WatchListener<String> = definedExternally): FSWatcher(source)

Watch for changes on filename, where filename is either a file or a directory, returning an FSWatcher.

Parameters

filename

A path to a file or directory. If a URL is provided, it must use the file: protocol.


Returns an async iterator that watches for changes on filename, where filenameis either a file or a directory.

const { watch } = require('node:fs/promises');

const ac = new AbortController();
const { signal } = ac;
setTimeout(() => ac.abort(), 10000);

(async () => {
try {
const watcher = watch(__filename, { signal });
for await (const event of watcher)
console.log(event);
} catch (err) {
if (err.name === 'AbortError')
return;
throw err;
}
})();

On most platforms, 'rename' is emitted whenever a filename appears or disappears in the directory.

All the caveats for fs.watch() also apply to fsPromises.watch().

Since

v15.9.0, v14.18.0

Return

of objects with the properties: