example of using instanceof

instanceof-example.js

// NOTE: `app` parameter is an instance of Express.js.
module.exports = function(app) {
  var socketIO;
  socketIO = require('socket.io').listen(app);
  socketIO.sockets.on('connection', function(socket) {
    console.log("CONNECTED");
    console.log(socket instanceof socket.constructor);
  });
};