Php: Detect if user included the javascript-snippet or not, on their website
<p>I got a simple javascript-file, wich my users need to include on their website for example. I want to detech if the snippet is include or not. The way I'm going to detect it, is by using a unique key in the js-file, for anyone who needs to know.</p>

<p>Been searching a lot for this, but haven't come up with any results yet.</p>
