hostname is a property of both the Link and the Location objects and specifies the server name, subdomain and domain name (or IP address) of a URL. Assuming a link (stored in the first element of the links property) to a URL ...

http://home.newco.com/products/enquiries.htm#local?email=name@otherco.com

...the following code would display the hostname property of it:

Code:
document.write(document.links[0].hostname)

Output:
home.newco.com

NOTE:

Although the hostname property can be set at any time, it is safer to set the href property to change a link.