JavaScript to get around IE caching downloadable EXE's?

I have a problem with my site and IE users. When I post updated versions of my setup.exe file, the users are still getting the old version. Doing a little reading, I realized that IE is caching EXE's. I had heard this was a problem with images, but I didn't know that it affected downloads as well.

Not being much of a JavaScript dev, I put together the following code to append a random querystring variable to the end of the file name:

function UpdateDownloadLinks() {
  var i;
  var linkLength;
  var linkType;
  var linkCount = document.links.length
  var randNum = Math.round((Math.random()*10000));
  
  for (i = 0; i < linkCount; i++) {
    linkLength = String(document.links[i].toString()).length;
    linkType = String(document.links[i].toString().toLowerCase()).substring(linkLength, linkLength - 3);
    if ((linkType == "exe") || (linkType  == "zip"))
      document.links[i].href += "?fid=" + randNum;
  }
}

Code (markup):

This seemed to work for IE6, but IE7 users were complaining that the download was just "setup". IE7 stripped the ".exe" extension off the file.

So I have several questions:
(1) What exactly are the caching problems with IE and do they vary by version (as I suspect)?
(2) Is there a solution to this?


Thanks.

 

theres a few ways to get around it.
1. name your program with the version number tacked on the end.
2. send a no cache header.

to get around your current problem you would have to make some type of serving script to send the following header.

Content-Disposition: attachment; filename="setup.exe"

Code (markup):

 

Thanks ndreamer. I'll look into the Content-Disposition option.