JSFiddle - React, Tailwind, and code Playground

HTML

<!-- Show the console to see output -->

JavaScript

var addresses = [
	'google.com',							// should return 'com'
  'https://google.com.uk',	// should return 'uk'
  'yahoo.cn/foo/bar.foo',		// should return 'cn'
  'file:///usr/local'				// should fail
];

for (var index in addresses) {
	console.log(tld(addresses[index]));
}

function tld(address) {
	// handle edge-cases
	if (typeof address == 'undefined' || address.indexOf('file:///') != -1)
		return undefined;
		
	var part = address;
	
	//remove http://
	if (part.indexOf('//') != -1)
		part = part.split('//')[1];
		
	//isolate domain
	if (part.indexOf('/') != -1)
		part = part.split('/')[0];  
	
	//get tld
	if (part.indexOf('.') != -1) {
		var all = part.split('.');
		part = all[all.length - 1];	
	}
	return part;
}