Javascript return just primary domain name

Question

Is there a lazy way to get a variable for "top level" host without resorting to if()?

example.com: return example.com,
cabbages.example.com: return example.com,
carrots.example.com: return example.com,
otherexample.com: return otherexample.com,
cabbages.otherexample.com: return otherexample.com,
carots.otherexample.com: return otherexample.com,

You could try [regular expressions](http://eloquentjavascript.net/09_regexp.html) or [String.prototype.split](https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/String/split) — nils, Nov 03 '15 at 16:51
What about `cabbages.example.co.uk`? Doing this right requires knowing the naming conventions for each top-level domain. — Barmar, Nov 03 '15 at 17:01

score 0 · Accepted Answer · answered Nov 03 '15 at 17:01

0

With the test cases that you provided, one way is to use use split, splice, and join.

window.location.hostname.split(".").splice(-2,2).join(".")

Plenty of ways to write a regular expression, but one is

window.location.hostname.match(/[^\.]+\.[^\.]+$/)

answered Nov 03 '15 at 17:01

epascarello

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That's great, thank you very much. Went with split splice and join – Doug Fir Nov 03 '15 at 17:07
what about www.google.com.au, it should be google.com.au, instead of com.au – user192344 Apr 15 '19 at 08:45

score 0 · Answer 2 · answered Nov 03 '15 at 17:03

You can use a regular expression to get the part of the string that you want:

url = url.replace(/^.*?([^\.]+\.[^\.]+)$/, '$1');

Demo:

var urls = [
  'example.com',
  'cabbages.example.com',
  'carrots.example.com',
  'otherexample.com',
  'cabbages.otherexample.com',
  'carots.otherexample.com'
];

for (var i = 0; i < urls.length; i++) {
  var url = urls[i].replace(/^.*?([^\.]+\.[^\.]+)$/, '$1');
  console.log(url);
}

Javascript return just primary domain name

2 Answers2