Gets and sets the host name portion of the URL. The key difference betweenurl.host and url.hostname is that url.hostname does not include the port.

const myURL = new URL('https://example.org:81/foo');
console.log(myURL.hostname);
// Prints example.org

// Setting the hostname does not change the port
myURL.hostname = 'example.com';
console.log(myURL.href);
// Prints https://example.com:81/foo

// Use myURL.host to change the hostname and port
myURL.host = 'example.org:82';
console.log(myURL.href);
// Prints https://example.org:82/foo

Invalid host name values assigned to the hostname property are ignored.