gaze

What is gaze?

The 'gaze' npm package is a file watcher that uses native OS events to notify you of changes to files and directories. It is useful for tasks such as automatically reloading a server, rebuilding assets, or running tests when files change.

What are gaze's main functionalities?

Watch Files

This feature allows you to watch for changes in JavaScript files in the current directory. When a change is detected, it logs the event type and the file path.

const gaze = require('gaze');
gaze('*.js', function(err, watcher) {
  if (err) throw err;
  console.log('Watching files...');
  this.on('all', function(event, filepath) {
    console.log(event + ': ' + filepath);
  });
});

Watch Directories

This feature allows you to watch for changes in JavaScript files within the 'lib' directory and its subdirectories. It logs the event type and the file path when a change is detected.

const gaze = require('gaze');
gaze('lib/**/*.js', function(err, watcher) {
  if (err) throw err;
  console.log('Watching directories...');
  this.on('all', function(event, filepath) {
    console.log(event + ': ' + filepath);
  });
});

Get Watched Files

This feature allows you to retrieve a list of files currently being watched. It logs the list of watched files to the console.

const gaze = require('gaze');
gaze('*.js', function(err, watcher) {
  if (err) throw err;
  console.log('Watching files...');
  console.log(this.watched());
});

Other packages similar to gaze

chokidar

Chokidar is a highly efficient and reliable file watcher that uses native OS events. It offers more features and better performance compared to 'gaze', including support for recursive watching, symlink following, and more robust handling of edge cases.

watch

The 'watch' package is a simple file watcher that uses polling to detect changes. It is less efficient than 'gaze' and 'chokidar' but can be useful for simpler use cases where native OS events are not required.

node-watch

Node-watch is another file watcher that uses native OS events. It is similar to 'gaze' but offers a simpler API and fewer features. It is suitable for basic file watching tasks.

README

gaze

A globbing fs.watch wrapper built from the best parts of other fine watch libs.
Compatible with Node.js 0.10/0.8, Windows, OSX and Linux.

Features

• Consistent events on OSX, Linux and Windows
• Very fast start up and response time
• High test coverage
• Uses native OS events but falls back to stat polling
• Option to force stat polling with special file systems such as networked
• Downloaded over 400K times a month
• Used by Grunt, gulp, Tower and many others

Usage

Install the module with: npm install gaze or place into your package.json and run npm install.

var gaze = require('gaze');

// Watch all .js files/dirs in process.cwd()
gaze('**/*.js', function(err, watcher) {
  // Files have all started watching
  // watcher === this

  // Get all watched files
  this.watched(function(watched) {
    console.log(watched);
  });

  // On file changed
  this.on('changed', function(filepath) {
    console.log(filepath + ' was changed');
  });

  // On file added
  this.on('added', function(filepath) {
    console.log(filepath + ' was added');
  });

  // On file deleted
  this.on('deleted', function(filepath) {
    console.log(filepath + ' was deleted');
  });

  // On changed/added/deleted
  this.on('all', function(event, filepath) {
    console.log(filepath + ' was ' + event);
  });

  // Get watched files with relative paths
  this.relative(function(err, files) {
    console.log(files);
  });
});

// Also accepts an array of patterns
gaze(['stylesheets/*.css', 'images/**/*.png'], function() {
  // Add more patterns later to be watched
  this.add(['js/*.js']);
});

Alternate Interface

var Gaze = require('gaze').Gaze;

var gaze = new Gaze('**/*');

// Files have all started watching
gaze.on('ready', function(watcher) { });

// A file has been added/changed/deleted has occurred
gaze.on('all', function(event, filepath) { });

Errors

gaze('**/*', function(error, watcher) {
  if (error) {
    // Handle error if it occured while starting up
  }
});

// Or with the alternative interface
var gaze = new Gaze();
gaze.on('error', function(error) {
  // Handle error here
});
gaze.add('**/*');

EMFILE errors

By default, gaze will use native OS events and then fallback to slower stat polling when an EMFILE error is reached. Gaze will still emit or return the error as the first argument of the ready callback for you to handle.

It is recommended to advise your users to increase their file descriptor limits to utilize the faster native OS watching. Especially on OSX where the default descriptor limit is 256.

In some cases, native OS events will not work. Such as with networked file systems or vagrant. It is recommended to set the option mode: 'poll' to always stat poll for those situations.

Minimatch / Glob

See isaacs's minimatch for more information on glob patterns.

Documentation

gaze([patterns, options, callback])

• patterns {String|Array} File patterns to be matched
• options {Object}
• callback {Function}
  • err {Error | null}
  • watcher {Object} Instance of the Gaze watcher

Class: gaze.Gaze

Create a Gaze object by instancing the gaze.Gaze class.

var Gaze = require('gaze').Gaze;
var gaze = new Gaze(pattern, options, callback);

Properties

• options The options object passed in.
  • interval {integer} Interval to pass to fs.watchFile
  • debounceDelay {integer} Delay for events called in succession for the same file/event
  • mode {string} Force the watch mode. Either 'auto' (default), 'watch' (force native events), or 'poll' (force stat polling).
  • cwd {string} The current working directory to base file patterns from. Default is process.cwd().

Events

• ready(watcher) When files have been globbed and watching has begun.
• all(event, filepath) When an added, changed or deleted event occurs.
• added(filepath) When a file has been added to a watch directory.
• changed(filepath) When a file has been changed.
• deleted(filepath) When a file has been deleted.
• renamed(newPath, oldPath) When a file has been renamed.
• end() When the watcher is closed and watches have been removed.
• error(err) When an error occurs.
• nomatch When no files have been matched.

Methods

• emit(event, [...]) Wrapper for the EventEmitter.emit. added|changed|deleted events will also trigger the all event.
• close() Unwatch all files and reset the watch instance.
• add(patterns, callback) Adds file(s) patterns to be watched.
• remove(filepath) removes a file or directory from being watched. Does not recurse directories.
• watched([callback]) Returns the currently watched files.
  • callback {function} Calls with function(err, files).
• relative([dir, unixify, callback]) Returns the currently watched files with relative paths.
  • dir {string} Only return relative files for this directory.
  • unixify {boolean} Return paths with / instead of \\ if on Windows.
  • callback {function} Calls with function(err, files).

FAQs

Why Another fs.watch Wrapper?

I liked parts of other fs.watch wrappers but none had all the features I needed when this library was originally written. This lib once combined the features I needed from other fine watch libs but now has taken on a life of it's own (gaze doesn't wrap fs.watch or fs.watchFile anymore).

Other great watch libraries to try are:

• paulmillr's chokidar
• mikeal's watch
• github's pathwatcher
• bevry's watchr

Contributing

In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code using grunt.

Release History

• 0.6.0 - Uses native OS events (fork of pathwatcher) but can fall back to stat polling. Everything is async to avoid blocking, including relative() and watched(). Better error handling. Update to globule@0.2.0. No longer watches cwd by default. Added mode option. Better EMFILE message. Avoids ENOENT errors with symlinks. All constructor arguments are optional.
• 0.5.1 - Use setImmediate (process.nextTick for node v0.8) to defer ready/nomatch events (@amasad).
• 0.5.0 - Process is now kept alive while watching files. Emits a nomatch event when no files are matching.
• 0.4.3 - Track file additions in newly created folders (@brett-shwom).
• 0.4.2 - Fix .remove() method to remove a single file in a directory (@kaelzhang). Fixing Cannot call method 'call' of undefined (@krasimir). Track new file additions within folders (@brett-shwom).
• 0.4.1 - Fix watchDir not respecting close in race condition (@chrisirhc).
• 0.4.0 - Drop support for node v0.6. Use globule for file matching. Avoid node v0.10 path.resolve/join errors. Register new files when added to non-existent folder. Multiple instances can now poll the same files (@jpommerening).
• 0.3.4 - Code clean up. Fix path must be strings errors (@groner). Fix incorrect added events (@groner).
• 0.3.3 - Fix for multiple patterns with negate.
• 0.3.2 - Emit end before removeAllListeners.
• 0.3.1 - Fix added events within subfolder patterns.
• 0.3.0 - Handle safewrite events, forceWatchMethod option removed, bug fixes and watch optimizations (@rgaskill).
• 0.2.2 - Fix issue where subsequent add calls dont get watched (@samcday). removeAllListeners on close.
• 0.2.1 - Fix issue with invalid added events in current working dir.
• 0.2.0 - Support and mark folders with path.sep. Add forceWatchMethod option. Support renamed events.
• 0.1.6 - Recognize the cwd option properly
• 0.1.5 - Catch too many open file errors
• 0.1.4 - Really fix the race condition with 2 watches
• 0.1.3 - Fix race condition with 2 watches
• 0.1.2 - Read triggering changed event fix
• 0.1.1 - Minor fixes
• 0.1.0 - Initial release

License

Copyright (c) 2014 Kyle Robinson Young
Licensed under the MIT license.