Track a specific event (javascript) with analytics

Hello All,
I'm showing an ad for a client of mine, by using a java script which is inserted in the footer section of my wordpress site. What the script do is showing an overlay with the site of my client (you can check it out here: informiran.net). The script itself is as follows:

<!-- advertising someIDhere=-->
<script data-cfasync="false" type="text/javascript">
(function (document, window) {
var c = document.createElement("script");
c.type = "text/javascript";
c.async = !0;
c.src = "//linktojavasript.js?=" + Math.floor((new Date).getTime());
var a = !1;
try {
a = parent.document.getElementsByTagName("script")[0] || document.getElementsByTagName("script")[0];
} catch (e) {
a = !1;
}
a || ( a = document.getElementsByTagName("head")[0] || document.getElementsByTagName("body")[0]);
a.parentNode.insertBefore(c, a);
})(document, window);
</script>
<!-- end advertising -->
I have analytics up and running and I track all other aspects of the user befaviour. So my question is, how can I make google analytics to track how many times the script has shown the popup target webpage.

Thanks in advance.