winreglib

Windows Registry Utility Library

A library for querying and watching the Windows Registry.

Prerequisites

winreglib requires N-API version 3 and the following Node.js versions:

• v10.2.0 or newer

Installation

npm install winreglib

Introduction

winreglib is a native Node.js addon for querying the Windows Registry. The API is synchronous.

Currently winreglib only supports read operations. It can support write operations someday if need and time exists.

Example

import winreglib from 'winreglib';

const key = 'HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion';
const results = winreglib.list(key);

console.log(`${results.root}\\${results.path}`);

console.log('  Subkeys:');
for (const subkey of results.subkeys) {
	console.log(`    ${subkey}`);
}

console.log('  Values:');
for (const valueName of results.values) {
	console.log(`    ${valueName} = ${winreglib.get(key, valueName)}`);
}

API

get(key, valueName)

Get a value for the given key and value name.

Argument	Type	Description
key	String	The key beginning with the root.
valueName	String	The name of the value to get.

Returns a String, Number, Buffer, Array.<String>, or null depending on the value.

If key or valueName is not found, an Error is thrown.

const value = winreglib.get('HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion', 'ProgramFilesDir');

console.log(value);

C:\Program Files

list(key)

Retreives all subkeys and value names for a give key.

Argument	Type	Description
key	String	The key beginning with the root.

Returns an Object with the resolved resolvedRoot (String), key (String), subkeys (Array[String]), and values (Array[String]).

If key is not found, an Error is thrown.

const result = winreglib.list('HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Setup');

console.log(result);

{ resolvedRoot: 'HKEY_LOCAL_MACHINE',
  key: 'HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Setup',
  subkeys:
   [ 'DPI',
     'ImageServicingData',
     'OC Manager',
     'OOBE',
     'PnpLockdownFiles',
     'PnpResources',
     'State',
     'Sysprep',
     'SysPrepExternal',
     'WindowsFeatures' ],
  values: [ 'LogLevel', 'BootDir' ] }

watch(key)

Watches a key for changes in subkeys or values.

Argument	Type	Description
key	String	The key beginning with the root.

Returns a handle (EventEmitter) that emits "change" events. Call handle.stop() to stop watching the key.

const handle = winreglib.watch('HKLM\\SOFTWARE');
handle.on('change', evt => {
	console.log(`Got change! type=${evt.type} key=${evt.key}`);
	handle.stop();
});

The "change" event object contains a change "type" and the affected "key".

Event Type	Description
add	The key was added.
change	A subkey or value was added, changed, deleted, or permissions modified, but we don't know exactly what.
delete	The key was deleted.

watch() can track keys that do not exist and when they are created, a change event will be emitted. You can watch the same key multiple times, however each returned handle is unique and you must call handle.stop() for each.

Due to limitations of the Win32 API, watch() is unable to determine what actually changed during a change event type. You will need to call list() and cache the subkeys and values, then call list() again when a change is emitted and compare the before and after.

Note that watch() does not support recursively watching for changes.

Advanced

Debug Logging

winreglib exposes an event emitter that emits debug log messages. This is intended to help debug issues under the hood. The average user will never need to use this, however it would be handy when filing a bug.

winreglib.on('log', msg => console.log(msg));

Alternatively, winreglib uses the amazing snooplogg debug logger where you simply set the SNOOPLOGG environment variable to winreglib (or *) and it will print the debug log to stdout.

License

This project is open source under the Apache Public License v2 and is developed by Axway, Inc and the community. Please read the LICENSE file included in this distribution for more information.