Trying to perform ajax/xhr via vanillajs. Am I doing this right? If not then please advise. Thanks :)

vanilla_js_xhr.js

const XMLHttpRequest = require('xhr2');
const xhr = new XMLHttpRequest();

xhr.open('GET', 'http://twitter.com/DesmondANIMUS/');
xhr.send(null);

xhr.onreadystatechange = function () {
    var DONE = 4; // readyState 4 means the request is done.
    var OK = 200; // status 200 is a successful return.
    if (xhr.readyState === DONE) {
        if (xhr.status === OK)
            console.log(xhr.responseText); // 'This is the returned text.'
    } else {
        console.log('Error: ' + xhr.status); // An error occurred during the request.
    }
    console.log("Done");
}