node-watch

node-watch

A neat fs.watch wrapper.

Installation

npm install node-watch

Example

var watch = require('node-watch');

watch('somedir_or_somefile', { recursive: true }, function(evt, name) {
  console.log(name, ' changed.');
});

This is a completely rewritten version, much faster and in a more memory-efficient way. So with recent nodejs versions under OS X or Windows you can do something like this:

// watch the whole disk
watch('/', { recursive: true }, console.log);

Why

• Some editors will generate temporary files which will cause the callback function to be triggered multiple times.
• When watching a single file the callback function will only be triggered once.
• Missing an option to watch a directory recursively.
• Recursive watch is not supported on Linux or in older versions of nodejs.

Notice

• The recursive option is defaults to be false since v0.5.0.
• Parameters in the callback function always provide event name since v0.5.0.

Events

The events provided by the callback function would be either update or remove.

watch('./', function(evt, name) {

  if (evt == 'remove') {
    // on delete
  }

  if (evt == 'update') {
    // on create or modify
  }

});

Watcher object

watch function returns a fs.FSWatcher like object as the same as fs.watch.

var watcher = watch('./', { recursive: true });

watcher.on('change', function(evt, name) {
  // callback
});

watcher.on('error', function(err) {
  // handle error
});

// close
watcher.close();

Extra options

• filter: Filter files or directories or skip to watch them.

var options = {
  recursive: true,
  filter : function(name) {
    return !/node_modules/.test(name);
  }
};

// ignore node_modules
watch('mydir', options, console.log);

Other ways to filter

a) filtering directly inside the callback function:

watch('./', { recursive: true }, function(evt, name) {
  // ignore node_modules
  if (!/node_modules/.test(name)) {
    // do something
  }
});

b) filtering with higher order function:

function filter(pattern, fn) {
  return function(evt, name) {
    if (pattern.test(name)) {
      fn(evt, name);
    }
  }
}

// watch only for js files
watch('.', filter(/\.js$/, console.log));

Misc

1. Watch mutiple files or directories in one place

watch(['file1', 'file2'], console.log);

2. Catch errors after deleting a watched directory on Windows

watch('somedir', console.log)
  .on('error', function() {
    // ignore it if you wish.
  });