Question

On this page (temporary location) I am trying to detect if the browser supports Float64Array, and if not to redirect to this page, which tells user to use a different browser. However, the redirect does not appear to work on MSIE 8 on Windows XP 32-bit, because the error occurs first in libfreecell-solver.min.js which is only loaded after that.

How can I fix it?

Answer 1

IE browsers have their own built-in browser detection scheme that no one else adopted. You can rely on it for any IE version below 10, I think. It looks like this:

<!--[if gte IE 8]>
<p>You're using a recent version of Internet Explorer.</p>
<![endif]-->

<!--[if lt IE 7]>
<p>Hm. You should upgrade your copy of Internet Explorer.</p>
<![endif]-->

<![if !IE]>
<p>You're not using Internet Explorer.</p>
<![endif]>

You would basically add in a <!--[if lte IE 9]--> tag with a <script> tag inside it to do a window.location call to wherever you wanted to send crap browsers to. Probably not as elegant as you wanted, but it’s reliable, at least.

Taken from this page: http://msdn.microsoft.com/en-us/library/ms537509(v=vs.85).aspx

Update:
Looking at your actual scripts, I see a parse/syntax error right away.

(function() {
    try {
        var a = new Float64Array(1);
        return; //no need
    } catch(e) {
        window.location.replace("../../js-fc-solve/incompatible-browser.html");
    } // Closing the catch block, but not closing the function block
)();

Add a brace:

(function() {
    try {
        var a = new Float64Array(1);
        return; //no need
    } catch(e) {
        window.location.replace("../../js-fc-solve/incompatible-browser.html");
    } // Closing the catch block
})(); // Close the function block before trying to call the anonymous function

That may or may not cause the user to get redirected before trying to include the library with the other error in it. Also, it may or may not detect all the features you need detected to run the library. I’d say it depends on the browser (no irony intended).

If that doesn’t work, you can do an intermediate page that decides whether to send the user to the solver page or display the incompatible browser message.