Detect Visits that Block JavaScript Tracking

Creation date: 8/10/2023 10:55 PM Updated: 8/29/2025 5:18 PM

OVERVIEW

This feature classifies each Visit as "JS Unblocked" or "Blocked JS". This classification is shown in the "Visits that Block JS" report & segment.

Most analytics tools have a major flaw: they rely on JavaScript code to track Visits. If a Visit blocks this code (or the tracking beacon), the analytics tool isn't able to "see" the Visit.

Angelfish doesn't have this flaw because it doesn't rely on JavaScript-based tracking.

USE CASES

Here are some of the ways to use this feature:

Verify the data reported by an agency to customers
Validate the effectiveness of other web analytics solutions
Measure the untracked clicks & conversion for your inbound marketing campaigns
Identify the percentage of Visits that block Google Analytics tracking

In the rest of this help article, we'll use the Google Analytics use case to provide supporting examples.

REQUIREMENTS

You'll need:

1) An Angelfish Profile that uses one of these Tracking Methods:

SID
USR
IPUA
IP

2) Access logs that contain:

hits for normal web traffic
hits for a JavaScript tracking beacon

The access logs can be from your web server or from a CDN. Angelfish natively supports Azure CDN, Amazon CloudFront, and Google Cloud CDN.

Most web analytics tools let you configure a local request for a JavaScript tracking beacon. With Angelfish Tracking Code, the local request is made by default.

For the Google Analytics use case, you would add a code snippet to your GA code, and copy the __ga4.gif file to the path specified in the code snippet.

This is explained in the following article - see steps 1 & 2:

Google Analytics Local Request

SETUP TASKS

1) Create a new Profile

Use one of these Tracking Methods: SID, USR, IPUA, IP

2) Enable "Detect Visits that Block JS"

This is a checkbox in the Settings tab of the Profile's config. You also need to enter the filename of the tracking beacon.

3) Process Data

Only process a handful of logs the first time you process data - this lets you make sure the data looks correct before you process everything.

Some bots interact with JavaScript & tracking beacons. You may need to add a Filter or config setting to remove them from the reports.

For the Google Analytics use case, here's how we'd set this up.

1) Profile

The Angelfish Profile will most likely use IPUA, although we prefer to use SID or USR when possible. Be sure to point the Datasource at the correct access logs.

2) Enable Feature

Enter "__ga4.gif" as the Tracking File Name, or whatever filename is specified in the code snippet.

3) Process Data

Once processing is complete, open the "Visits that Block JS" report to verify the data.

NOTES

The "JS Unblocked" and "Blocked JS" classifications can be isolated with a processing Filter. This means you can have reports that only contain traffic from "Blocked JS" Visits...or only from "JS Unblocked."

This feature isn't available for Profiles that use a JS-based Tracking Method, or for the SPO Tracking Method.

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