Is there a way to get top level domain name from the url

for e.g., "<https://images.google.com/blah>" => "google"

I found this: 

```
var domain = new URL(pageUrl).hostname; 

```

but it gives me "images.google.com" instead of just google.

Unit tests I have are:

```
https://images.google.com   => google
https://www.google.com/blah => google
https://www.google.co.uk/blah => google
https://www.images.google.com/blah => google

```