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Editorial Team
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Asked: 2026-05-13T13:04:29+00:00

I’m developing a JavaScript application that’s meant to be run either from a web

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I’m developing a JavaScript application that’s meant to be run either from a web server (over http) or from the file system (on a file:// URL).

As part of this code, I need to use XMLHttpRequest to load files in the same directory as the page and in subdirectories of the page.

This code works fine (“PASS”) when executed on a web server, but doesn’t work (“FAIL”) in Internet Explorer 8 when run off the file system:

<html><head>
<script>
window.onload = function() {
  var xhr = new XMLHttpRequest();
  xhr.open("GET", window.location.href, false);
  xhr.send(null);
  if (/TestString/.test(xhr.responseText)) {
    document.body.innerHTML="<p>PASS</p>";
  }
}
</script>
<body><p>FAIL</p></body>

Of course, at first it fails because no scripts can run at all on the file system; the user is prompted a yellow bar, warning that “To help protect your security, Internet Explorer has restricted this webpage from running scripts or ActiveX controls that could access your computer.”

But even once I click on the bar and “Allow Blocked Content” the page still fails; I get an “Access is Denied” error on the xhr.open call.

This puzzles me, because MSDN says that “For development purposes, the file:// protocol is allowed from the Local Machine zone.” This local file should be part of the Local Machine Zone, right?

How can I get code like this to work? I’m fine with prompting the user with security warnings; I’m not OK with forcing them to turn off security in the control panel.

EDIT: I am not, in fact, loading an XML document in my case; I’m loading a plain text file (.txt).

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1 Answer

  1. Editorial Team

    Hmm, could it be the difference between the native XMLHttpRequest object and the ActiveX one? I seem to remember something about that. That is, instead of 

    var xhr = new XMLHttpRequest();

    try 

    var xhr = new ActiveXObject("MSXML2.XMLHTTP");

    Obviously, put some checks in place to see if the browser supports ActiveX. Of course, this is limited to IE only, as well.

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