RedirectUrl info lost after doing postback in client-side code
<p>My login page works like this: when you enter it, javascript reads some info from you, writes it into some input and does submit so that the read data can be read and processed on server.</p>

<pre><code>&lt;script language="javaScript" type="text/javascript"&gt;
    function getUserInfo() 
    {
            var userInfo = xyz.GetSecureBox();
            form1.info.value = userInfo;
            form1.read.value = "true";
            form1.submit();
    }
&lt;/script&gt;
</code></pre>

<p>Server code authenticates user or not, depending on the provided data.  </p>

<p>The problem is that when you try to enter a different page, let's make it Default.aspx, you are redirected to login page with RedirectUrl parameter so that you can be authenticated. But after postback made i javascript the RedirectUrl information is lost. How can I preserve it?  </p>

<p>Well I can of course read that query string parameter in js and write it into some input. How can I access query string parameters in JS? And maybe there is a different way?</p>
