JAVASCRIPT

domain regex

/^[a-zA-Z0-9][a-zA-Z0-9-]{1,61}[a-zA-Z0-9].[a-zA-Z]{2,}$/

regex domain

^((?!-))(xn--)?[a-z0-9][a-z0-9-_]{0,61}[a-z0-9]{0,1}.(xn--)?([a-z0-9-]{1,61}|[a-z0-9-]{1,30}.[a-z]{2,})$

get domain name with regex

const urls = [
  'www.abc.au.uk',
  'https://github.com',
  'http://github.ca',
  'https://www.google.ru',
  'http://www.google.co.uk',
  'www.yandex.com',
  'yandex.ru',
  'yandex',
  'devmaster.auxitaplatform.com',
]

urls.forEach(url => console.log(url.replace(/.+//|www.|..+/g, '')))