Note: This feature is available in Web Workers.
The referrer read-only property of the SecurityPolicyViolationEvent interface is a string representing the referrer for the resources whose Content Security Policy (CSP) was violated. This will be a URL or null.
A string representing the URL for the referrer of the resources whose policy was violated, or null.
document.addEventListener("securitypolicyviolation", (e) => {
console.log(e.referrer);
});