fsevents's Introduction

fsevents

Native access to MacOS FSEvents in Node.js

The FSEvents API in MacOS 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-platform file watching module that uses fsevents, check out Chokidar.

Installation

npm install fsevents

Usage

const fsevents = require('fsevents');
const stop = fsevents.watch(__dirname, (path, flags, id) => {
  const info = fsevents.getInfo(path, flags, id);
}); // To start observation
stop(); // To end observation

The callback passed as the second parameter to .watch get's called whenever the operating system detects a a change in the file system. It takes three arguments:

(path: String, flags: Number, id: String) => {}

path - the item in the filesystem that have been changed
flags - a numeric value describing what the change was
id - an unique-id identifying this specific event

`fsevents.getInfo(path, flags, id): FsEventInfo => {}`

The getInfo function takes the path, flags and id arguments and converts those parameters into a structure that is easier to digest to determine what the change was.

The FsEventsInfo has the following shape:

/**
 * @typedef {'created'|'modified'|'deleted'|'moved'|'root-changed'|'unknown'} FsEventsEvent
 * @typedef {'file'|'directory'|'symlink'} FsEventsType
 */
{
  "event": "created",
  "path": "file.txt", // {FsEventsEvent}
  "type": "file",    // {FsEventsType}
  "changes": {
    "inode": true,   // Had iNode Meta-Information changed
    "finder": false, // Had Finder Meta-Data changed
    "access": false, // Had access permissions changed
    "xattrs": false  // Had xAttributes changed
  },
  "flags": 0x100000000
}