[h3r0]

The issue with having a JS timer would have to be cheating. But the method WILL be storing a unix time stamp somewhere. You could go with storing it in a PHP session..

Code:

$date = new DateTime(); $_SESSION['last_submit_time'] = $date->getTimestamp();

This allows you to use AJAX or just use PHP and when the page loads inject the $_SESSION['last_submit_time'] into the JS.

But if you were feeling a little dangerous you can do some HTML5 Web Storage which is a local database http://www.w3schools.com/html/html5_webstorage.asp
Issue with that is that it could be edited by the user.


I would suggest going the pure PHP route (No Ajax) because what if a user doesn't have Javascript. Or use Ajax and fall back onto to PHP (This is probably the best and most professional route if you plan on making this a reusable piece of software to sell)