Iframe Cross Domain Tracking With GTM
Here I love to share the easiest way of GTM iframe tracking that I found ever. So, borrowing some code from GTM expert that everyone know – Simo Ahava.
I tested this below condition and was working well.

So, into the topic. Basically, we need only a CustomJs GTM variable with hitcall back function and rest is magic. 😀
Step I
Create a customJs variable named callBack
function() {
return function() {
try {
var gobj = window[window.GoogleAnalyticsObject];
var iframe = document.querySelector('#myIframe');
var tracker, linker;
if (gobj) {
tracker = gobj.getAll()[0];
linker = new window.gaplugins.Linker(tracker);
iframe.src = linker.decorate(iframe.src);
}
} catch(e) {}
}
}
Please refer – Orginal Blog Post for code explained.
Step II
Now, at the Universal Analytics tag in GTM >> MoreSettings > Fields to set >> the add :
hitcallback with variable {{callback}
Done! like magic, your iframe link will be decorated. To check if its working use RealTime Analytics or Inspect element to find cid appended to iframe.