Socket IO CDN
<script src="https://cdnjs.cloudflare.com/ajax/libs/socket.io/1.4.5/socket.io.min.js"></script>
Better Bear
<script src="https://cdnjs.cloudflare.com/ajax/libs/socket.io/1.4.5/socket.io.min.js"></script><!-- CDNJS -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/socket.io/4.4.1/socket.io.min.js" ></script>
<!-- jsDelivr -->
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/socket.io.min.js" ></script>
<!-- unpkg -->
<script src="https://unpkg.com/[email protected]/dist/socket.io.min.js" ></script>
<script src="https://cdn.socket.io/4.4.1/socket.io.min.js" integrity="sha384-fKnu0iswBIqkjxrhQCTZ7qlLHOFEgNkRmK2vaO/LbTZSXdJfAu6ewRBdwHPhBo/H" crossorigin="anonymous"></script><script src="https://cdn.socket.io/socket.io-3.0.1.min.js"></script>