Extracting the domain name from a URL using javascript

Question

I need a general script/pattern to extract the main domain name from URLs. I have the following attempt that failed.

Let use say I have this link1 and need to extract the main domain name (google.co.uk) without the sub-domain (mail). I made this script which worked fine with .co.uk but will fail with websites that has one top-level domain name like: .com and .com.

Is there a better way to extract main domain name from ANY URL? The URL is constructed as follows:

https://(optional sub-domain)*(domain name with two or three top-level domain name)(optional forward slash followed by text)*

The * refer to zero or more times.

var link1="https://mail.google.co.uk/link/link/link";
var url = new URL(link1);
var domain = url.hostname.split('.').slice(-3).join('.');
console.log("The domain name is: "+ domain);

In the above code, I expect: google.co.uk

It could work because the link has two parts in the top-level domain name (.co.uk) so -3 works. But I need the code to work with this link as well:

var link1="https://mail.google.com/link/link/link";

And I need the output to be: google.com

But the problem is that the code produces:

mail.google.com

And I only want the main domain name: google.com

EDIT: Some of the expected output examples are here:

1) In mail.google.co.uk it should be: google.co.uk

2) In mail.google.com it should be: google.com

3) In link.mail.google.com/link/link it should be: google.com

4) In link.link2.mail.google.com it should be: google.com

i.e. just the main domain name without sub-domains or links after the domain name. The top-level domain name can be in the fom of (.com, .net, .org, etc.) or in the form of (.co.uk, .co.us, etc). The top-level domain name should be captured either if it is one part or two parts (my code capture only two parts).

@Nikola Lukic that link is to extract the top-level domain name. I am asking about the main domain name in addition to the top-level domain name. e.g. google.com, google.co.uk. — None
– None, Commented Mar 29, 2018 at 12:51
Problem for parsing i see with '.' and double dot. You must make some validation object and define concrete roles. For example make this ".co.uk" like exception case . Program must know when is two or one dot valid result. — Nikola Lukic
– Nikola Lukic, Commented Mar 29, 2018 at 13:00
@Nikola Lukic it is for any URL. I can not make exception. It is not only .co.uk but can be any thing. For example: .co.us or any other type. — None
– None, Commented Mar 29, 2018 at 13:02
Possible duplicate of Issue while capturing Top-Level Domain from URL — Pradeep Pati
– Pradeep Pati, Commented Mar 29, 2018 at 14:00

JosephStevens · Accepted Answer · 2018-03-29 12:40:13Z

0

Sure if you wanted

"mail.google.co.uk"

you can just use

url.host

or if you wanted it with headers, use

url.origin

cheers!

answered Mar 29, 2018 at 12:40

JosephStevens

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