Adding jQuery to a 3rd party page fails
<p>I am trying out a few things, and among those I tried to insert jquery on a site, namely, <a href="http://www.tesco.com/wine" rel="nofollow">http://www.tesco.com/wine</a>. </p>

<p>For some reason, I was not able to able access jQuery even though I was able to successfully append a new script tag to the body element.  Also, the page seems to have a <code>window.$</code> function that I tried to delete with <code>delete window.$</code>. This, seems to return false for me. How do you make something undeleteable?</p>

<p>Here is the code I used to append the jQuery script to the document:</p>

<pre><code>var s = document.createElement('script');
s.src = "http://ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.min.js";
document.body.appendChild(s)
</code></pre>

<p>It is working on other pages.</p>
