Question

Is there a way to prevent Internet Explorer from accessing the web application?

In fact, I wouldn’t mind displaying a static page informing them to download Firefox. I want to stop supporting IE, but I’m not sure the best approach.

Answer 1

There are basically three ways to detect the browser.

1. Check the user agent. This method is unreliable and generally should
   not be used, although there are some cases where it might be okay.
2. Check javascript object support. This is usually done
   when executing javascript code and is a good thing to do in order to
   make sure objects exist before you try to use them. There are some
   objects that might be exclusively defined in IE, but there is
   a chance that some other browser will have the object defined as
   well.
3. Use conditional comments. This is the route I would use with since
   you are looking specifically for IE (conditional comments only apply
   to IE). This option will also give you the ability to target certain
   versions of IE reliably.

Here is an example that would redirect if the browser is IE <= 7.

<!--[if lte IE 7]>
<script>
window.location = 'download-firefox.html';
</script>
<![endif]-->