Extracting only the domain and top level domain from a URL String

Question

I am trying to create a javascript function that can extract only the 'domain' and 'top-level domain' from a url string.

The current questions on StackOverFlow do not resolve the answer for non-urls too.

Examples:

https://www.google.com/imgres?imgurl -> google.com

yahoo.com/mail -> yahoo.com

http://helloworld.net/index/test/help -> helloworld.net

www.stackoverflow.com/ -> stackoverflow.com

invalid.url -> "return false or an empty string"

Any/All help is welcome and appreciated. Thank you.

Unless wanting this for learning purposes, there is already something that will do that: URL, though it does need to have the protocol part for it to be valid input, and will have to strip the subdomain parts (www) to get the output you seek — Patrick Evans
– Patrick Evans, Commented Jan 15, 2018 at 20:10
using the window.location as the parameter for the URL method — blubberbo
– blubberbo, Commented Jan 15, 2018 at 20:13
Possible duplicate of How to get top level domain (base domain) from the url in javascript — elbecita
– elbecita, Commented Jan 15, 2018 at 20:15

sp00m · Accepted Answer · 2018-01-15 20:27:18Z

1

A regex can suit your needs, for example:

^(?:https?://)?(?:[^/]+\.)?([^./]+\.[^./]+).*$

See on Debuggex

In JS:

function extractDomain(url) {
  return url.replace(/^(?:https?:\/\/)?(?:[^\/]+\.)?([^.\/]+\.[^.\/]+).*$/, "$1");
}

If you want to handle TLDs that contain dots (like .co.uk), then I'm afraid the only solution is to hardcode them, for example:

^(?:https?://)?(?:[^/]+\.)?([^./]+\.(?:co\.uk|com|de|es|fr)).*$

See on Debuggex

edited Jan 15, 2018 at 20:27

answered Jan 15, 2018 at 20:16

sp00m

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Comments

Mikhail Zharnikov · Accepted Answer · 2018-01-15 20:24:44Z

0

This is quite simple.

window.location.href variable stores the current url of the website.

With this variable, you can get the top domain.

var url = window.location.href
var split1 = url.split('//')[1];   // Get the string except the protocol.
var split2 = split1.split('/')[0];    // Get the domain url.
// Get top domain url.
var domain = split2;
if (split2.substring(0, 4) == 'www.')
    domain = split2.slice(4)

variable domain is the value you want.

edited Jan 15, 2018 at 20:24

answered Jan 15, 2018 at 20:19

Mikhail Zharnikov

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3 Comments

sp00m Over a year ago

This will fail for https://accounts.google.com or even https://foo.bar.foo.bar.

Mikhail Zharnikov Over a year ago

In that case, the top domain will be "accounts.google.com". I think. And it will work like that.

Mikhail Zharnikov Over a year ago

Sorry, I misspelled the code. When getting split2 variable, variable split1 must be used but I used url (my mistake.)

Ozymandias · Accepted Answer · 2025-05-01 18:32:52Z

-2

function getBaseHostname(urlStr: string): false | string {
  let url;
  try {
    url = new URL(urlStr);
  } catch (e) {
    return false;
  }
  return url.hostname.split('.').splice(-2).join('.');
}

the other answers overcomplicate it

answered May 1 at 18:32

Ozymandias

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