Javascript include_once
<p>I have coded a page that has two div one beside the other. The first one serves as a nav tree that, when clicked, loads a page in the right div with AJAX. I have to include a javascript file when one of the page is loaded.</p>

<p>I have managed to do jsut that and all works perfectly but each and every time that someone want to see the page, it includes the corresponding javascript page. This seems to me as a major leak and I am not so familiar with javascript development.</p>

<p>Question: Is there a way, when including the js file, to ensure that it was not previously included?</p>
