Read websocket communication via userscript

Question

How can a greasemonkey script / Chrome's user-script intercept a running websocket communication?

My goal is to have additional statistics for a in-browser game

Answer 1

Credit to: https://github.com/Cryoscalpel

Not sure if this works in all ws games but you can create a proxy websocket message logger.

WebSocket.prototype.send = new Proxy(WebSocket.prototype.send, {
          apply: function(target, scope, args) {
             if(typeof(args[0]) === 'string') {
                let json = JSON.parse(args[0]);
                     console.log(json)
           }
                  let data = target.apply(scope, args);
                      return data;
        }
     })

Answer 2

You may use Firefox, then add the Firebug module then add & use websocket-monitor module to monitor websocket.

If you want to hook websocket from javascript you may also use wshook.