AJAX is Broken in IE11

I POST HTTPRequests to my server for an XML and XSL pair

For IE I do this using:

request = new ActiveXObject("Microsoft.XMLHTTP");

request.open("POST",url,async);

request.send(formData);

and I receive the responses using:

xslObject=request.responseXML;

xmlObject=request.responseXML;

To Transform I test for IE and process as follows:
if (window.ActiveXObject) {
   myHTML=xmlObject.transformNode(xslObject);
   responseElement.innerHTML=myHTML;

}

This was working until in a brash act of naivety and folly I said "Yes" to IE11.

Now all is sadness and despair.

Can anyone help me out of this "fine mess that Microsoft has got us into"?