socket_2.html

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <script src="/socket.io/socket.io.js"></script>
  <script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
  <title>socket.io</title>
</head>
<body>
    <div id="date"></div>
    <textarea id="text"></textarea>
    <br>
    <button id="btn">send</button>
    <script>
      var socket = io.connect();

      socket.on('date', function(data) {
        $('#date').text(data.date);
      });

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

      $(document).ready(function(){
        $('#btn').click(function() {
          var msg_text = $('#text').val();
          socket.emit('client_data', {
            // 'letter': String.fromCharCode(e.charCode)
            'letter': msg_text
          });
          $('#text').val('');
        });
      });
    </script>
</body>
</html>