fsevents

What is fsevents?

The fsevents npm package is a Node.js module that provides native and efficient file system event watching on macOS. It is designed to be used by Node.js applications to receive notifications when the contents of a directory change, including file creations, modifications, and deletions. It leverages the macOS FSEvents API for optimal performance and accuracy.

What are fsevents's main functionalities?

Watching for file changes

This feature allows you to watch a directory for changes and execute a callback function whenever a change is detected. The callback receives the path of the changed file, flags that describe the change, and an event ID.

const fsevents = require('fsevents');
const watcher = fsevents.watch('/path/to/dir', (path, flags, id) => {
  console.log('File changed:', path);
});
watcher.start();

Stopping the watcher

This feature allows you to stop watching for file changes. It is useful when you no longer need to monitor a directory or when your application is shutting down.

watcher.stop();

Other packages similar to fsevents

chokidar

Chokidar is a file watching package that works across multiple platforms, including macOS, Windows, and Linux. It provides a high-level API for file system notifications and is often used as an alternative to fsevents for cross-platform compatibility. Chokidar uses fsevents on macOS for performance but falls back to other methods on other operating systems.

watch

The watch package is another file system watcher for Node.js. It is less efficient than fsevents because it uses polling to detect changes rather than native file system events. This can result in higher CPU usage and less immediate change detection compared to fsevents.

node-watch

Node-watch is a simple and lightweight file watching library. Like chokidar, it aims to provide a consistent API across different platforms. It does not rely on native extensions, which can make it easier to install than fsevents, but it may not offer the same level of performance on macOS.

README

fsevents

Native access to OS X FSEvents in Node.js

The FSEvents API in OS X allows applications to register for notifications of changes to a given directory tree. It is a very fast and lightweight alternative to kqueue.

This is a low-level library. For a cross-compatible file watching module that uses fsevents, check out Chokidar.

• Module Site & GitHub
• NPM Page

Installation

$ npm install fsevents

Usage

var fsevents = require('fsevents');
var watcher = fsevents(__dirname);
watcher.on('fsevent', function(path, flags, id) { }); // RAW Event as emitted by OS-X
watcher.on('change', function(path, info) { }); // Common Event for all changes
watcher.start() // To start observation
watcher.stop()  // To end observation

Events

• fsevent - RAW Event as emitted by OS-X
• change - Common Event for all changes
• created - A File-System-Item has been created
• deleted - A File-System-Item has been deleted
• modified - A File-System-Item has been modified
• moved-out - A File-System-Item has been moved away from this location
• moved-in - A File-System-Item has been moved into this location

All events except fsevent take an info object as the second parameter of the callback. The structure of this object is:

{
  "event": "<event-type>",
  "id": <eventi-id>,
  "path": "<path-that-this-is-about>",
  "type": "<file|directory|symlink>",
  "changes": {
    "inode": true, // Has the iNode Meta-Information changed
    "finder": false, // Has the Finder Meta-Data changed
    "access": false, // Have the access permissions changed
    "xattrs": false // Have the xAttributes changed
  },
  "flags": <raw-flags>
}

MIT License

Copyright (C) 2010-2014 Philipp Dunkel

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.