Dynamicly loading stylesheets with js and handling stylesheets onload event

dynamic_stylesheet.js

//Its very tricky to load LINK tags dynamicly and listen to their onload event, i found lots of hacks and tricks.
//This is the best and cleanest option that i came up with
//Basicly you just load the link file with ajax and put it inside a STYLE tag.
//This is a pure JS solution, no jQuery

function createXMLHTTPObject() {

    var XMLHttpFactories = [
        function () {return new XMLHttpRequest()},
        function () {return new ActiveXObject("Msxml2.XMLHTTP")},
        function () {return new ActiveXObject("Msxml3.XMLHTTP")},
        function () {return new ActiveXObject("Microsoft.XMLHTTP")}
    ];

    var xmlhttp = false;
    for (var i = 0; i < XMLHttpFactories.length; i++) {
        try {
            xmlhttp = XMLHttpFactories[i]();
        }
        catch (e) {
            continue;
        }
        break;
    }
    return xmlhttp;
}

function sendRequest(url, callback, postData) {
    var req = createXMLHTTPObject();
    if (!req) return;
    var method = (postData) ? "POST" : "GET";
    req.open(method, url, true);
    req.setRequestHeader("X-Requested-With", "XMLHttpRequest");
    req.setRequestHeader('User-Agent', 'XMLHTTP/1.0');
    if (postData)
        req.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
    req.onreadystatechange = function () {
        if (req.readyState != 4) return;
        if (req.status != 200 && req.status != 304) {
            //          alert('HTTP error ' + req.status);
            return;
        }
        callback(req);
    };
    if (req.readyState == 4) return;
    req.send(postData);
}

function insertAfter(newNode, referenceNode) {
    referenceNode.parentNode.insertBefore(newNode, referenceNode.nextSibling);
}

//This is the important part
sendRequest(url, function (request) {
    var style = document.createElement('style');
    style.type = 'text/css';
    if (style.styleSheet) {
        style.styleSheet.cssText = response;
    } else {
        style.appendChild(document.createTextNode(response));
    }
    insertAfter(style, oreiginalLinkElement);
    //or
    document.getElementsByName('head')[0].appendChild(style);
});