Get Host Name

by Dinesh Chitlangia

HTML

<div id="result"></div>

JavaScript

var urlInput = "http://one.two.roothost.co.uk/page.html";

function extractDomain(url) {
    var domain;
    //find & remove protocol (http, ftp, etc.) and get domain
    if (url.indexOf("://") > -1) {
        domain = url.split('/')[2];
    } else {
        domain = url.split('/')[0];
    }

    //find & remove port number
    domain = domain.split(':')[0];

    return domain;
}

function getRootHostName(url) {
    var parts = extractDomain(url).split('.');
    var partsLength = parts.length - 3;

    //parts.length-3 assuming root hostname is of type abc.xyz.pp
    for (i = 0; i < partsLength; i++) {
        parts.shift(); //remove sub-domains one by one
    }
    var rootDomain = parts.join('.');

    return rootDomain;
}

document.getElementById("result").innerHTML = getRootHostName(urlInput);