Extract top domain from a given url.
npm and node.js friendly version of segmentio/top-domain
$ npm install top-domain
var topDomain = require('top-domain');
console.log(topDomain('http://example.com/'));
//example.com
console.log(topDomain('http://example.co.uk/'));
//example.co.uk
console.log(topDomain('http://www.example.co.uk/parameter1/parameter2/'));
//example.co.uk