Adswerve Data Layer Inspector+

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We are pleased to launch the latest version of the Data Layer Inspector+

What is the Inspector+?

The Data Layer Inspector+ is a Chrome extension that provides real-time, information-rich viewing of data layer activity and Google Analytics hits as they happen in the Developer Tools console. In addition, it has other features that support development and web analytics debugging.

Adswerve Date Inspector menu


The UI packs all the features into a compact, easy-to-use set of options. 

Added Functionality

Provides additional abilities beyond the basic features: e.g., intercept the console (show Inspector+ output when console logging is blocked by a site), push events to the data layer, insert a GTM container, and add code to the page.

Adding functionality with Adswerve Data Inspector

Control Output

Enhance or hide outputs: e.g., console highlights, specific events, specific properties and CD names.

Auto-detect feature in Data Layer Plus tool

Additional options are available under "Control output" by expanding the "Developer output" submenu.  These include Show Mouse Events, Show Timing, Show postMessage, Show Mutations, and Hide Call Stack.

Developer Output for Adswerve Data Layer Inspector

Other Analytics

Observe code and network activity for other analytics implementations: Google Marketing, Facebook, Tealium, Adobe DTM, Adobe Analytics, mParticle, Coremetrics, Segment, GTM Server-Side, and Custom.

Adobe Analytics and other analytics data layer inspector

Handy Links

Get links to relevant documentation and resources. 

Handy Links with data layer inspector

Basic use

The badge will indicate current settings with color and short text. 

– On

– Off

– Classic Mode

– dataLayer.push

– GTM Inserted

– Multiple Added Functions 

– Code Inserted

Console Output



Href is document.location.href at the time the Inspector loads on the page, and could be different from what is in the address bar or what is sent in DL and DP, especially when the page is a Single Page Application (SPA). Shortcut: Clicking on the HRef will take you to the source code in the Sources tab. Similar to right-clicking and selecting View Source, but you can "Pretty Print" the source in the developer tools view.


This is document.referrer when the Inspector loads on the page. It may not be the same as seen in the GA hit in the dr parameter. Analytics.js does not include the referrer from the same domain and single page applications  Notes: In Single Page Applications (SPA), this banner remains at the top, and the HRef and referrer do not change.


Use the Tilde (~) to exclude non-Inspector console logs.  Make sure you have "All levels" selected.

Collapsed Banner

If you'd like to save space in the console, you can select "Collapse banner" in the "Control output" options. This will hide the hint and filter note. 


Data Layer Pushes

Anatomy of dataLayer.pushes (and other analytics calls)

Summary - console.groupCollapsed(...)

Console group summary in data layer inspector

The summary includes a logo, brand, object, function, key and value. If there is no event, and multiple keys, "Object - Expand for details" is displayed.


Each push contains details of the push: e.g., stringified object, pointer to the push currently in memory (it will not be there on the next page when preserve log is checked), and the call stack. When showing timing, it will include seconds to the thousandth since Document Start (when the Inspector was first loaded). Uses: See the stringified content of the data layer push. See evaluations when the Summary is not green. Access the Call Stack. See timing when turned on.

Object Pushed (or Arguments)

The stringified object shows the type of entity pushed to the data layer (Object or Arguments) and a formatted version of the entity (that will be there on the next page, when preserve log is checked, and can be copied and pasted into the console to replay). Use: See the values of the push, even from previous pages.

Currently in Memory

This is a link to the actual object in memory. The topmost line is accurate for when the object was pushed to the data layer. When you click on the arrow to the left of the object, (after the colon), the object will expand and an information symbol will display. This indicates that the value of the object was evaluated on the click. Notice that the event value in the top line is different from the second line. This is because the event value was modified after the push and before the click.

Uses: To see what is in the data layer push when the object is too large or too complex to stringify.

Call Stack

Links to the code that executed from the start to the console.log are shown in the expanded "Call Stack." The top links are inside the Inspector+. The bottom link is to the line of code that initiated the push. The link before function [as push], is to the code that called dataLayer.push.

Uses: Understanding where the data layer push comes from or what code initiated the push.

Common dataLayer pushes

These pushes are seen on every page when GTM is installed and only once per page. Gotchas: Using these events in a Single Page Application. For example, using gtm.js as a pageview in a SPA will only send a pageview when the page first loads. 


Pushed from gtm and gtag snippets.

gtm.start is the time the push was made MDN - "the numeric value corresponding to the current time - the number of milliseconds elapsed since January 1, 1970 00:00:00 UTC with leap seconds ignored." The stack is not available when the script runs before the Inspector was loaded.

(function(w,d,s,l,i) {
  w[l] = w[l] || [];
    'gtm.start': new Date().getTime(),
    event:       'gtm.js'
  var f = d.getElementsByTagName(s)[0],
      j = d.createElement(s),
      dl = l != 'dataLayer' ? '&l=' + l : '';
  j.src= '//'+i+dl;

Gotchas: 1. gtag and gtm pushes look different in the data layer, but are seen as the same in GTM. A data layer push from gtag with Arguments containing js and the date/time will be evaluated by GTM the same as the above event: 'gtm.js'

Needed data in the hit that isn't there when the event triggers. 
Uses: Understanding when the GTM Pageview is triggered and, when the call stack is available, seeing the code that pushes the event.


Pushed from GTM when "The DOMContentLoaded event fires when the initial HTML document has been completely loaded and parsed, without waiting for stylesheets, images, and subframes to finish loading." MDN The document object is ready.

Uses: When you need to access the DOM. 


"The load event is fired when a resource and its dependent resources have finished loading." MDN   Gotchas: gtm.load is not a reliable event in some sites, especially publication sites, because resources may load very slowly and sometimes get blocked.  

Network Hits: Anatomy of Network Hits


Data layer GA4 page view example

The summary includes a logo, brand, type and more information. The Google Tag ID appears after the event name.  The brand and type are color-coded with three levels: green is good, brown is worth noting and red is an error.

Data sent

The stringified object shows the data sent (that will be there on the next page, when preserve log is checked).

Data Layer tool data sent example


General Conventions

Green Is Good 

Pageview hit is valid and contains recommended CD(s)


Brown Is a Notice 

Pushes should have an event key: Multiple GTM containers push gtm.js Snippet not in the head, as per spec


Red Is Bad 

Duplicate Pageviews, dataLayer reset


Examples of Evaluations

DataLayer Reset

Sometimes, data layers are initialized incorrectly, and after data has been pushed to the data layer. When the data layer has data and is reset using syntax like dataLayer = [], and the Inspector is observing the data layer, you will see the following error in the console. NOTE: This evaluation can only happen if the Inspector+ is observing the data layer at the time of the reset. 

Demonstration: Inject this code into a site with a dataLayer.
document.addEventListener("DOMContentLoaded",(event) => {
    window.dataLayer = [{stuff: 'stuffing'}]


E-commerce Object Data

Required structures, types and content specified by Google in the Enhanced Ecommerce (UA) Developer Guide are evaluated and, if there is a notice or error, the push will be highlighted and the details will include the reason(s). 


GTM Snippet Location

The GTM snippet should be installed in the HEAD element. If it is not, you’ll see a console log of  a notice with a link to the script. You can click the arrow to see the script. Right-click on the script to "Reveal in Elements Panel".

GTM, Optimize, and gtag Configuration Evaluated

These evaluations are in early alpha. The evaluation is done on gtm.load (when all should have been loaded). Sorting through the implementation combinations and the implications is an emerging effort. 

Multiple containers using the same dataLayer
Multiple GTM Containers





On/off Auto detect dataLayer

Naming the dataLayer can provide better sequencing of pushes and hits


Classic Mode

The Original Version

Use: When you feel nostalgic about the simple days of Digital Analytics.


Add Functionality

Pushes an object to the dataLayer (or named data layer: e.g., anotherDatalayer) when the Inspector+ is loaded on the page. Usually used when testing GTM and the data needs to be in the data layer asap.

Example of pushing to an object of the dataLayer

To use, add JSON formatted key (e.g. "event") and value (e.g. "dataLayer-push") pairs with colon in between, separated by commas for multiple sets.  

Insert GTM Container

Inserts a Google Tag Manager snippet into the page when the Inspector+ is loaded and the host is exactly what is in the Host: field, or, when RegEx is checked, the host matches the regex.

Inserting a GTM conttainer with data layer inspector tool

Use: When you want to add a GTM container to a page. Hint: To keep the inspector dropdown window open while you go and get the GTM ID and the URL, right-click on the dropdown window and select "Inspect".  Note: GTM not inserted:will be pushed to the console if the conditions for insertion do not match. 

Inject Code

Inserts a script tag into the head. The code will run immediately upon insertion.

Inject code with Adswerve data layer inspector tool

Use: When you want to add code to the page immediately or on an event. Hint: To delay until the DOM is ready, use addEventListener: e.g.

document.addEventListener("DOMContentLoaded",(event) => {
// Do your stuff here: e.g. dataLayer.push…
event: 'example-event',
stuff: 'stuffing'


Control Output

Collapse Banner

Reduces the space taken up by the banner.  Before:


Uses: When you don’t need to be reminded about the console filter: e.g., a tilde(~) excludes non-Inspector+ console messages. 

Show Client ID

Appends the client ID (cid) after the property ID of the pageview hit.

Show client ID with data layer inspector tool

Hide Highlights 

Turns off the highlights for hits. 

Hide highlights with data layer inspector tool

Uses: When you don't care if you don't see the hits and the highlights distract you. 

Hide Highlights 

Sometimes developers get verbose with data layer pushes and you may want to ignore one or more events. This uses a Regex match, so you can block multiple events you want with a well-formed regex. Use: Hide data layer push events.  

Show Hits to a Specific Property

This will limit the GA output to one specific property. Use: When there are multiple properties and you are only interested in one. 

CD Names

This feature will add the names of the CDs that are found in GA, to the network hit details and protocol definitions. Go to Custom Dimensions in the Custom Data area of Google Analytics admin panel, and you will see a green button that will allow you to add the CD names to the Inspector+. Make sure you have all of the CDs visible. There is also a way to share the CDs with those that don't have access. The instructions and data will be logged to the console when you add the CD names. To reset (clear all): This will remove all properties' CDs.

Use: When you’re implementing and QAing a bunch of CDs that you don't have memorized. 

Additional Options Under "Developer Output"


Show postMessage 

Listens to window.message and pushes to the dataLayer the origin, data and the MessageEvent.

Uses: Communication monitoring from iFrames is a common use case: e.g., cross-domain tracking, video events and ads. 

Show Mutations

Sets listeners on the head and body element of the DOM and logs the array of changes when they happen.

Uses: Answering the questions "What is changing, and when is it changing?"

Hide Call Stack

Does not retrieve and display the call stack in the dataLayer.push details.

Use: Declutter the dataLayer push details. Show Timing dataLayer.push The number of seconds since the document start (when the Inspector+ was first loaded), in thousands of seconds.

Use: Measure how long it takes for an event to happen or the duration of tag processing: push processing time. The number of milliseconds the code takes to process the push; from push to callback.

NOTE : Both gtag and GTM process dataLayer pushes.

Other Analytics

Google Marketing

Floodlight and other Google Marketing hits are displayed in the console.  

Adobe _satelite

Adobe's legacy tag management system, Dynamic Tag Manager, is being replaced by Launch. The feature is early Alpha, meaning it’s incomplete and may not be reliable.

Adobe Analytics

Like Google Analytics, Adobe sends tracking hits to their own platform. The Inspector+ will monitor the hits and display them in the console similarly to how GA hits are displayed. The feature is early Alpha, meaning it’s incomplete and may not be reliable.  

Recommendation: Use Adobe Experience Cloud Debugger  


This is a tag management system (TMS) that is agnostic to the analytics platform. The inspector monitors view and link calls and displays the calls in the console, similarly to data layer pushes. This feature is in advanced beta and is planned to be released to the public.

Recommendation: Use with Tealium Tools.


Like Google Analytics and Adobe, Facebook sends hits to their own platform. Like GA and Adobe hits, these are displayed in the console. The feature is currently public.

Recommendation: Use with: Facebook Pixel Helper.

Custom Analytics

This feature will add a "monkey patch" to a function on an object and when the function is called, it will log to the console something similar to dataLayer.push.  

Examples: window.addEventListener, dataLayer.push


A Common Question

Why does the dataLayer.push NOT expand when clicked?

This is usually due to the console filter either having something other than a tilde (~) or when the levels are too strict. 

Remedy: Use the tilde (~) for a filter and select "Default levels". 

Known Issue

Console output

Incomplete output when DevTools is opened

On some sites, when you open the console, the output is incomplete. Refresh the page to see the complete output.