Why does document.write() always cause the browsers tab to show the loading... indicator?
<p>I have nothing on a page except the following:</p>

<pre><code>&lt;script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.5.2/jquery.min.js"&gt;&lt;/script&gt;
&lt;script&gt;

$(function() {

   document.write('foo');

});

&lt;script&gt;
</code></pre>

<p>When I run this page in firefox the loading indicator in the current browser tab seems to be in perpetual motion, never stopping. Why does this happen? Is it indicating that the document.write script runs ceaselessly?</p>
