Time count - from frontend to backend : <p>I'm thinking to make a simple timer, so when the timer is clicked, the time starts to count and then I can stop it and the time passed will be saved into the DB.</p>

<p>But there's some tricks to it, as I figured out:</p>

<p>1) When the tab(of the current timer) is switched to another, the time count isn't trusty, due the low priority on the inactive tabs.</p>

<p>2) How can I varify the time passed with PHP in backend? (I've thought of making AJAX call every XX seconds to varify it with backend, but how can I make counter like this in my backend with PHP? Is this even possible using PHP?</p>

<p>P.S. I don't mind to drop legacy browsers, but I want to support all the modern ones(except the Edge :) )</p>
