create a Cross Origin Resource Sharing enabled request

createCorsRequest.js

function createCorsRequest(method, url) {
    var xhr = new XMLHttpRequest();
    if ("withCredentials" in xhr) {
        xhr.open(method, url, true);
    } else if (typeof XDomainRequest != "undefined") {
        xhr = new XDomainRequest();
        xhr.open(method, url);
    } else {
        xhr = null;
    }
    
    xhr.setRequestHeader("Content-Type", "application/json");
    return xhr;
}