Untitled

<!DOCTYPE html>
<html>
<head>
  <title>Socket.IO chat</title>
  <style>
    * { margin: 0; padding: 0; box-sizing: border-box; }
    body { font: 13px Helvetica, Arial; }
    form { background: #000; padding: 3px; position: fixed; bottom: 0; width: 100%; }
    form input { border: 0; padding: 10px; width: 90%; margin-right: 0.5%; }
    form button { width: 9%; background: rgb(130, 224, 255); border: none; padding: 10px; }
    #messages { list-style-type: none; margin: 0; padding: 0; }
    #messages li { padding: 5px 10px; }
    #messages li:nth-child(odd) { background: #eee; }
  </style>
</head>
<body>
  <ul id="messages"></ul>
  <form action="" class="form">
    <input id="m" autocomplete="off" />
    <button class="btn">Send</button>
  </form>

  <script src="/socket.io/socket.io.js"></script>
  <script>
    let socket = io();
    let form = document.querySelector('.form');
    let btn = document.querySelector('.btn');
    let input = document.querySelector('#m');
    let all_msg = document.querySelector('#messages');

    btn.addEventListener('click', (e) => {
      e.preventDefault();

      socket.emit('chat message', input.value);

      input.value = '';

      return false;
    });

    socket.on('add message', (data) => {
      let li = document.createElement('li');
      li.innerText = data.message;
      all_msg.appendChild(li);
    })
  </script>

</body>
</html>