fs.watch(filename[, options][, listener])
监视 filename
的变化,其中 filename
是文件或目录。
filename
<string> | <Buffer> | <URL>options
<string> | <Object>persistent
<boolean> Indicates whether the process should continue to run as long as files are being watched. Default:true
.recursive
<boolean> Indicates whether all subdirectories should be watched, or only the current directory. This applies when a directory is specified, and only on supported platforms (See caveats). Default:false
.encoding
<string> Specifies the character encoding to be used for the filename passed to the listener. Default:'utf8'
.signal
<AbortSignal> allows closing the watcher with an AbortSignal.
listener
<Function> | <undefined> Default:undefined
- Returns: <fs.FSWatcher>
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)
. eventType
is 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>.