Extracting Domain Name using Javascript

On a page with following URL

https://www.blogger.com/blogger.g

This code snippet would give an alert of blogger.com

<script type="text/javascript">
    var firstDot = window.location.hostname.indexOf('.');
    var lastDot = window.location.hostname.lastIndexOf('.');
   
    var tld = window.location.hostname.substring(lastDot);
    var isSubdomain = firstDot < window.location.hostname.lastIndexOf(tld);
   
    var domain;
    if (isSubdomain) {
        domain = window.location.hostname.substring(firstDot == -1 ? 0 : firstDot + 1);
    }
    else {
      domain = window.location.hostname;
    }
alert(domain);
</script>