Yes, there are already a dozen SOCKS v5-capable proxy server and/or client modules on npm, however I thought I'd throw my own implementations into the ring for anyone who is interested.
Features:
* SOCKS v5 client and server implementations in one module (obviously), with APIs similar to `net.Server` and `net.Socket`
* CONNECT request support (no BIND or UDP -- yet...)
* IPv4, IPv6, and remote DNS support
* Modular authentication handling system with "no authentication" and user/password authentication handlers built-in
* Interruptible parsers for reliability
* Ability for the server to intercept requests instead of passing the connection through to its intended destination
* Tests
* Maintained
* Written in JavaScript
Install via: npm install socksv5
Github/Documentation:
https://github.com/mscdex/socksv5