Get JSON Async

foo.js

function loadTextFileAjaxSync(filePath, mimeType) {
    var xmlhttp = new XMLHttpRequest();

    xmlhttp.open("GET", filePath, false);

    if (mimeType != null) {
        if (xmlhttp.overrideMimeType) {
            xmlhttp.overrideMimeType(mimeType);
        }
    }

    xmlhttp.send();

    if (xmlhttp.status == 200)
        return JSON.parse(xmlhttp.responseText);
    else
        // TODO Throw exception
        return null;
}