可从URL行访问的XML，但不能从脚本访问

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 (eg 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.