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simple-tree-watcher

Watches the FileSystem for changes

SimpleTreeWatcher

Build Status

Watches a directory tree for changes

Hopefully it actually works unlike other watch libaries

Example:

const SimpleTreeWatcher = require('simple-tree-watcher');
 
var dir = process.argv[2];
console.log("watching: ", dir);
 
var watcher = new SimpleTreeWatcher(dir);
watcher.on('add',    function(f, s)     { show("add   :", f, s    ); });
watcher.on('create', function(f, s)     { show("create:", f, s    ); });
watcher.on('remove', function(f, s, s2) { show("remove:", f, s, s2); });
watcher.on('change', function(f, s)     { show("change:", f, s    ); });
 
function show(event, filepath, stat, oldStat) {
  console.log(event, filepath, stat.isDirectory() ? "dir" : "file");
}

Docs

create an instance of SimpleTreeWatcher and attach events.

new SimpleTreeWatcher(path, options)

SimpleTreeWatcher is an EventEmitter so it has the standard EventEmitter api.

Events

'add'

Emitted for every entry when you first start. Passed filename and stat

'create'

Emitted when an file or folder is created. Passed filename and stat

'remove'

Emitted when a file is deleted. Passed filename and last stat

'change'

Emitted when a file is change. Passed the filename, current stat, previous stat

Options

filter

A function that is passed the path for every file and directory. It should return true to keep the file or directory or false to reject it. The path passed is relative to the original path when SimpleTreeWatcher was created.

Methods

close

Stops watching the tree. No more events will be sent.

Philosophy / Goals

My hope is there will be no surprises. You will never get a change or remove event for something that you didn't previously get an add or create event for.

I didn't feel like adding a globbing options is a good thing. It would just bloat the library. You can write your own filter in a 1-3 lines of code so it seemed best to let you pick your own filtering methods

Similarly some watch function have debouncing options etc. All of that can be layered over this level. No need to bloat/clutter/obfusticate this simple library.

Platform Issues

Each platform behaves slightly different. In my testing

OSX

Add a file get a create event for the file

Windows

Add a file get a create event for the file and a change event for the parent folder

Also on Windows a watcher may hold a lock or temp lock on a folder. I haven't tracked this down. In the tests I delete a subfolder which internally I instantly get an 'EPERM' error from the watcher for that folder. I handle that case. But, at the end of the test I delete all the test files. Those deletes failed unless I closed the watcher.

Linux

Add a file get both create event and a change event for the file