JSFiddle - React, Tailwind, and code Playground

HTML

<div id="results"></div>

JavaScript

function isDomain(domain, url) {
    var pat = '^https?://(?:[^/@:]*:[^/@]*@)?(?:[^/:]+\.)?' + domain + '(?=[/:]|$)';
    var re = new RegExp(pat, 'i');
    return re.test(url);
}

var url = 'http://test.github.com/v3/';

alert(isDomain('github.com', url));