The hostname property of the HTMLAnchorElement interface is a string containing either the domain name or IP address of the <a> element's href. If the URL does not have a hostname, this property contains an empty string, "". IPv4 and IPv6 addresses are normalized, such as stripping leading zeros, and domain names are converted to IDN.
See URL.hostname for more information.
A string.
// An <a id="myAnchor" href="/en-US/docs/HTMLAnchorElement"> element is in the document
const anchor = document.getElementById("myAnchor");
anchor.hostname; // returns 'developer.mozilla.org'HTMLAnchorElement interface it belongs to.