Obtaining Google Analytics ClientID with Tag Manager

Anyone dealing with Measurement Protocols / CRMs may always need to store and retrieve ClientID for tasks like sending offline transactions, managing leads/ refunds etc.

This post assumes you are using GTM for GA implementation with Universal Analytics.

Step 1

Create a Custom JavaScript variable as below.

function(){
 return ga.getAll()[0].get('clientId');
}

Or define this as a JS variable.

Above script can be used when there is only one GA ID firing in the site, if multiple GA’s are present, use the script below specifying the GA ID:

function() {
        var trackers = ga.getAll();
        var i, len;
        for (i = 0, len = trackers.length; i < len; i += 1) {
            if (trackers[i].get('trackingId') === "UA-XXXXXXX-1") {
                return trackers[i].get('clientId');
            }
        }
    return 'nil';
}

Step 2

– Now we are almost done, what remains is to send this data to Google Analytics. As usual, many of us will send this a custom dimension or metrics or both.

We are done now. To make sure everthing is working, look for the variable created in GTM preview pane.