How to send data from socket.io client?

Question

JavaScript

Hello. I can not understand why the data from the client is not sent.
Server:

io.sockets.on('connection', function (client) {
    client.on('messageClient', function (data) {
      console.log(data.posX);
    });  
    client.emit('messageServer', function (data) {
      console.log(data);
    });  
});

customer

var socket = io.connect('http://46.101.151.182:3000');
  var sid = Math.round('');
  socket.on('connect', function () {

    console.log('Подключен!');

  });

  var ax, ay, acelX;

  window.ondevicemotion = function(e) {
    ax = e.accelerationIncludingGravity.x;
    ay = e.accelerationIncludingGravity.y;
    document.getElementById('info').innerHTML = ax+', '+ay;
  }


  socket.on('messageServer',function(data) {
    console.log(data);
  });

  socket.emit('messageClient',{posX:ax});

When the page loads, it shows undefined, and that's it. Further data is not received

Answer 1

When the page loads, it shows undefined, and that's it. Further data is not received

You are passing the value of the variable ax, and at the time of sending it is undefined, this shows. Try passing a string.
If you want a message to be sent to the ondevicemotion event, put
socket.emit('messageClient', { posX: ax });
inside the callback