WTF JSON?

client.js

ptt_btn.onmousedown = function(e){
	  	ptt=true;
		document.getElementById("tx").innerHTML=status_tx;
		if(ws.readyState == ws.OPEN) {
			var evt = '{"event": "ptt_on"}';
			ws.send(JSON.stringify(evt));
        }
	  } 

ouput.log

  DEBUG "{\"event\": \"ptt_on\"}"
  DEBUG {"event": "ptt_on"}
  ERROR Uncaught exception in /socket
Traceback (most recent call last):
  File "/Library/Python/2.7/site-packages/tornado/websocket.py", line 322, in wrapper
    return callback(*args, **kwargs)
  File "./server.py", line 140, in on_message
    if data["event"] == "connect":
TypeError: string indices must be integers
   INFO client disconnected

server.py

def on_message(self, message):
        # Check if message is Binary or Text
        if type(message) == str:
            #Processing of Binary Messages
        else:
            debug(message)
            data = json.loads(message)
            debug(data)
            if data["event"] == "connect":
                self.id = data['id']
                conns[self.id] = self
            elif data["event"] == "ptt_off":
                self.frame_buffer.process(self.id)
            else:
                info("Unknown event: {}".format(data))
            self.write_message('ok')