Get domain name without subdomains using JavaScript?

Question

How to get the domain name without subdomains?

e.g. if the url is \"http://one.two.roothost.co.uk/page.html\" how to get \"roothost.co.uk\"?

Answer 1

Here is a working JSFiddle

My solution works with the assumption that the root hostname you are looking for is of the type "abc.xyz.pp".

extractDomain() returns the hostname with all the subdomains. getRootHostName() splits the hostname by . and then based on the assumption mentioned above, it uses the shift() to remove each subdomain name. Finally, whatever remains in parts[], it joins them by . to form the root hostname.

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);

HTML

EDIT 1: Updated the JSFiddle link. It was reflecting the incorrect code.