document for socket code example

Example 1: socket io script

<script src="/socket.io/socket.io.js"></script>
<script>
  const socket = io();
</script>

Example 2: socket.io doc

const socket = new WebSocket('ws://localhost:3000');socket.onopen(() => {  socket.send('Hello!');});socket.onmessage(data => {  console.log(data);});