Where do smartphone clicks go from ad networks?

Question

JavaScript

Launched an advertising campaign. We started comparing the number of page requests from the server with js-tracking placed directly on the page itself (we placed the simplest script in the head tag)

<script>
        (function() {
            var xhr = new XMLHttpRequest();
            xhr.open('GET', '<?php echo $trackUrl; ?>', true);
            xhr.send();
        })();
</script>

As a result, we got statistics, from which it is clear that some of the mobile traffic (Android and iphones) requests the page, but the track does not work out. For what reasons can this happen?

Answer 1

On JS it is incorrect to consider, then it is necessary to analyze server logs. There are many reasons:
1. JS is disabled
2. I closed the page before the counter loaded
3. The counter was blocked by an ad blocker
, etc.