dots.node.fs.watch-file-options
Watch for changes on filename. The callback listener will be called each
time the file is accessed.
The options argument may be omitted. If provided, it should be an object. The options object may contain a boolean named persistent that indicates
whether the process should continue to run as long as files are being watched.
The options object may specify an interval property indicating how often the
target should be polled in milliseconds.
The listener gets two arguments the current stat object and the previous
stat object:
import { watchFile } from 'fs';
watchFile('message.text', (curr, prev) => {
console.log(`the current mtime is: ${curr.mtime}`);
console.log(`the previous mtime was: ${prev.mtime}`);
});
These stat objects are instances of fs.Stat. If the bigint option is true,
the numeric values in these objects are specified as BigInts.
To be notified when the file was modified, not just accessed, it is necessary
to compare curr.mtimeMs and prev.mtimeMs.
When an fs.watchFile operation results in an ENOENT error, it
will invoke the listener once, with all the fields zeroed (or, for dates, the
Unix Epoch). If the file is created later on, the listener will be called
again, with the latest stat objects. This is a change in functionality since
v0.10.
Using {@link watch } is more efficient than fs.watchFile and fs.unwatchFile. fs.watch should be used instead of fs.watchFile and fs.unwatchFile when possible.
When a file being watched by fs.watchFile() disappears and reappears,
then the contents of previous in the second callback event (the file's
reappearance) will be the same as the contents of previous in the first
callback event (its disappearance).
This happens when:
- the file is deleted, followed by a restore
- the file is renamed and then renamed a second time back to its original name
Watch for changes on `filename`. The callback `listener` will be called each
time the file is accessed.
The `options` argument may be omitted. If provided, it should be an object. The `options` object may contain a boolean named `persistent` that indicates
whether the process should continue to run as long as files are being watched.
The `options` object may specify an `interval` property indicating how often the
target should be polled in milliseconds.
The `listener` gets two arguments the current stat object and the previous
stat object:
```js
import { watchFile } from 'fs';
watchFile('message.text', (curr, prev) => {
console.log(`the current mtime is: ${curr.mtime}`);
console.log(`the previous mtime was: ${prev.mtime}`);
});
```
These stat objects are instances of `fs.Stat`. If the `bigint` option is `true`,
the numeric values in these objects are specified as `BigInt`s.
To be notified when the file was modified, not just accessed, it is necessary
to compare `curr.mtimeMs` and `prev.mtimeMs`.
When an `fs.watchFile` operation results in an `ENOENT` error, it
will invoke the listener once, with all the fields zeroed (or, for dates, the
Unix Epoch). If the file is created later on, the listener will be called
again, with the latest stat objects. This is a change in functionality since
v0.10.
Using {@link watch } is more efficient than `fs.watchFile` and `fs.unwatchFile`. `fs.watch` should be used instead of `fs.watchFile` and `fs.unwatchFile` when possible.
When a file being watched by `fs.watchFile()` disappears and reappears,
then the contents of `previous` in the second callback event (the file's
reappearance) will be the same as the contents of `previous` in the first
callback event (its disappearance).
This happens when:
* the file is deleted, followed by a restore
* the file is renamed and then renamed a second time back to its original namecljdoc is a website building & hosting documentation for Clojure/Script libraries
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