Question

When I type a certain URL in FF, I get the XML returned displayed on the screen, so the web service is apparently working. However, when I try to access it from a local HTML document running JS, I get unexpected behavior. The returned code is “200 OK” but there’s no text (or rather it’s an empty string) nor xml (it’s null) in the response sections according to FireBug.

This is how I make the call.

var httpObject = new XMLHttpRequest();
httpObject.open("GET", targetUrl, true);
httpObject.onreadystatechange = function () {
  if (httpObject.readyState == 4) {
    var responseText = httpObject.responseText;
    var responseXml  = httpObject.responseXML;
  }
}
httpObject.send(null);

Why does it happen and how do I tackle it?

Answer 1

That may be an HTTP header problem (e.g. missing Accept header); observe the headers sent by FF (you can use Firebug for that) and try to replicate them in your script (setRequestHeader).

Otherwise, that may be a “same origin policy” problem.