title: Use AJAX call to update a php session variable
body: <p>I have a PHP script that reads PDF files in a specified folder. I have each file split by page. I have stored these file names in an array and have created an index variable called <strong><code>$count</code></strong>. There are left (page down) and right (page up) arrows. I need <strong><code>$count</code></strong> to increment on page down and decrement on page up.  I know I need to use AJAX to do this, but the only data I have to send is the <em>onclick</em> event.</p>