Client

<html>
<body>
<script src="/socket.io/socket.io.js"></script>
<script src="http://code.jquery.com/jquery-1.10.1.min.js"></script>
<script>
  var socket = io.connect('http://localhost');

  socket.on('connect', function () {

    $('#button').click(function() {

    	var addtext = $('#text').val();

    	socket.emit('Text', addtext);


    });

    socket.on('add', function(data) {

    	socket.broadcast.emit('AAA');

    });

  });
</script>
</script>
<textarea id="aqui"></textarea><br />
<input type="text" name="text" id="text"><input type="button" name="button" id="button" value="Enviar mensaje">
</body>
</html>