src/rx-dom.js
function getCORSRequest() {
  var xhr = new root.XMLHttpRequest();
  if ('withCredentials' in xhr) {
    xhr.withCredentials = this.withCredentials ? true : false;
    return xhr;
  } else if (!!root.XDomainRequest) {
    return new XDomainRequest();
  } else {
    throw new Error('CORS is not supported by your browser');
  }
}
function getCORSRequest() {
  var xhr = new root.XMLHttpRequest();
  if ('withCredentials' in xhr) {
    xhr.withCredentials = this.withCredentials ? true : false;
    return xhr;
  } else if (!!root.XDomainRequest) {
    return new XDomainRequest();
  } else {
    throw new Error('CORS is not supported by your browser');
  }
}
Get CORS support even for older IE