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node-watch

fs.watch() wrapper of Nodejs

Node-watchj

A fs.watch wrapper to watch files or directories(recursively by default).

npm install node-watch
var watch = require('node-watch');
 
watch('somedir_or_somefile', function(filename) {
  console.log(filename, ' changed.');
});
  • 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 one time and then is seem to be unwatched.
  • Missing an option to watch a directory recursively.

This module currently does not differentiate event like rename or delete. Once there is a change, the callback function will be triggered.

recursive:Watch it recursively or not (defaults to true).

followSymLinks: Follow symbolic links or not (defaults to false).

maxSymLevel: The max number of following symbolic links, in order to prevent circular links (defaults to 1).

filter: node-watch will only watch elements that pass the test implemented by the provided function. The filter function is provided with a full path string argument(defaults to (fullPath)=>true ).

watch('somedir', { recursive: false, followSymLinks: true }, function(filename) {
  console.log(filename, ' changed.');
});

Since v0.4.0 watch() will return a [fs.FSWatcher](fs.FSWatcher like object, so you can close the watcher or detect change by change event instead of the old callback function.

var watcher = watch('./');
 
watcher.on('change', function(file) {
  // 
});
 
watcher.on('error', function(err) {
 
});
 
// close 
watcher.close();
 
watch(['file1', 'file2'], function(file) {
  // 
});

You can write your own filter function as a higher-order function. For example:

var filter = function(pattern, fn) {
  return function(filename) {
    if (pattern.test(filename)) {
      fn(filename);
    }
  }
}
// only watch for js files 
watch('mydir', filter(/\.js$/, function(filename) {
  // 
}));

Alternatively, supply a filter function in the options object. For example:

// don't watch node_modules folder 
var options = {
  filter : function(filename) {
    return !/node_modules/.test(filename);
  }
};
watch('mydir', options, function(filename) {
  // 
}));

The second approach helps avoiding the max open files limit