title: Get the client id of the message sender in socket.io?
body: <p>on the server side i got</p>
  
  <pre><code>socket.on('chat', function (data) {
      io.sockets.socket(data.clientid).emit('chat', {
          msg: data.msg,
          senderid : senderid
      });
  });
  </code></pre>
  
  <p>How can I get the get the senderid without the sender having to post their clientid through with the message?</p>