Last updated: August 27, 2026.
A referral-aware banner can orient visitors arriving on a deep page. Keep the article itself identical for everyone.
const referrer = document.referrer ? new URL(document.referrer) : null;
const external = referrer && referrer.origin !== location.origin;
if (external && !sessionStorage.getItem("referral-message-dismissed")) {
const banner = document.querySelector("#referral-message");
banner.hidden = false;
banner.querySelector("button").addEventListener("click", () => {
banner.hidden = true;
sessionStorage.setItem("referral-message-dismissed", "yes");
});
}Referrer data may be absent. Do not serve crawlers materially different content from what users receive.
