Get notification in node.js when file is added to directory

Question

I'm writing some node.js code in which I would like to trigger action when a file is loaded to a directory, or when that file is updated there --I'm expecting that the same file name will be replaced in the directory repeatedly.

So, when the node child process finishes saving a file to the watched directory, I would like to trigger subsequent processes that use that file:

This thread seemed related, but not quite explicit enough about how to know when the file is updated or replaced: Watch a folder for changes using node.js, and print file paths when they are changed

Implicitly, I also need to verify that the updating process to the file in the watched directory is complete before the next events would be triggered.

Thanks as always for your advice!

Answer 1

I think the thread you linked it pretty explicit, isn't it? You can either use the standard methods fs.watch and fs.watchFile , or a nice little wrapper such as https://github.com/paulmillr/chokidar . ie:

var chokidar = require('chokidar');

var watcher = chokidar.watch('dir/', {ignored: /^\./, persistent: true});

watcher
  .on('add', function(path) {console.log('File', path, 'has been added');})

Answer 2

You can use notify as well.

var Notify = require('fs.notify');

var files = [
  '/path/to/file',
  '/file/i/want/to/watch'
];

var notifications = new Notify(files);
notifications.on('change', function (file, event, path) {
  console.log('caught a ' + event + ' event on ' + path);
});

// if you want to add more files you can use the
notifications.add([path, morepaths]);

// kill everything
notifications.close();

But chokidar is better.