You can read 'High Performance Browser Networking' for free on O'Reilly's website. It has a chapter about WebSockets which talks about sending and receiving binary data: http://chimera.labs.oreilly.com/books/1230000000545/ch17.htm...

Library for handling binary with websockets, no commits since last year: https://github.com/binaryjs/binaryjs/

Blog post regarding the basics of binary data + websockets: http://blog.mgechev.com/2015/02/06/parsing-binary-protocol-d...