PortSwigger Academy Lab: https://portswigger.net/web-security/dom-based/controlling-the-web-message-source/lab-dom-xss-using-web-messages-and-json-parse
Portswigger's XSS cheat sheet: https://portswigger.net/web-security/cross-site-scripting/cheat-sheet
Window: postMessage() method documentation: https://developer.mozilla.org/en-US/docs/Web/API/Window/postMessage
Free Burp Suite Professional trial: https://portswigger.net/burp/pro/trial
