JavaScript knowledge required for GTM (Google Tag Manager)

A tag management system called Google Tag Manager allows you to configure and rapidly deploy tags on your website or mobile app using a simple web-based interface. It has the same capabilities as the Google tag. Tag Manager also supports tag version management and organization, community- and third-party-developed tag templates, enterprise collaboration tools, and security features. Tag Manager lets you quickly modify and deploy tags on your website from a web-based interface while also optimizing tag deployment and reducing tag configuration errors.

Topics of JavaScript needed to learn for Google Tag Manager (GTM)

Basic Syntax

A simple and dynamic computer programming language is called JavaScript. It is employed to produce dynamic client-side pages. It is a cross-platform, open-source language. The short name for the storage place where data will be saved in JavaScript is a variable.

Operators in JavaScript are symbols used to compute values or, to put it another way, allow us to perform operations on operands. The value is computed using the arithmetic operators (+, -, *, /), and the values are assigned to variables using the assignment operators (=, +=, %=). Knowledge of each of these operators and variables is necessary to use Google Tag Manager.

Data Types and Structural Types

Now you can control the tags on your website using Google Tag Manager, without having to change the code. Variables are supported by Google Tag Manager (GTM) so that you may use the page's content as part of your structured data. Instead of repeating the information in GTM, use variables to retrieve the structured data from the website. The likelihood of a mismatch between the page content and the structured data added by GTM increases when data is duplicated in GTM.

Using JavaScript to either produce all of your structured data or supplement the server-side rendered structured data is another technique to generate structured data. In any case, when Google Search produces the page, it may comprehend and utilize structured data that is included in the DOM.

Functions & Scope

A large amount of code can be declaring and condense into a single block that we can then use (and reuse) across our projects with the help of a function. Sometimes they use certain values as "parameters" and then produce a certain value as a result. It is a section of the program that allows access to a variable. In other words, a variable's accessibility and visibility depend on its scope.

Given that JavaScript resembles a language from the C family, it is logical to assume that scoping in JavaScript is comparable to that in the majority of back-end programming languages, for eg. C, C++, or Java. It would be best if you comprehended try-catch blocks and if-else expressions to use Google Tag Manager.

String Methods

Strings are used in JavaScript to represent and manipulate a group of characters. A string may represent both the primitive data type and an object. JavaScript automatically transforms raw strings into String objects so that even primitive strings may access and use String methods. Strings play a significant role in the Google Tag Manager code and are employed in several locations to track the HTML code for certain websites.

Array Methods

Any programming language can benefit greatly from using array methods. If you want to make your JavaScript smaller and frequently easier to understand, you must be able to use techniques like filter() and forEach(). Every element in the array is examined by the filter() method, which creates a new Array for each element that satisfies the test you provide in the callback. Each element in the array is received individually by the forEach() method, after which you may do anything you like with that element. The map() function iterates through each element of the array once more, but this time the callback's code is run against each element, and a new array is provided with the results.

DOM Element Variable in GTM

The Material Object Model (also known as the DOM) is a dynamic, hierarchical tree-like representation of the document on the website. It enables document manipulation, obtaining values for present website elements, and adding, editing, or removing others.

The page's HTML code may be seen by visiting any website and opening its source (for example, CTRL+U on Chrome (WIN)). This is the code that a programmer created to give the website its current appearance. Using the DOM to retrieve values for website elements carries significant risk. If you intend to scrape the DOM for your tracking implementation heavily, be aware that a developer may unintentionally change the website's content that breaks your GTM DOM Element variables.


These are the six topics about JavaScript that are required to be mastered to learn Google Tag Manager. Many topics are needed to become an Advanced level Google Tag Manager expert. The benefit of utilizing GTM, or any library, is that the library often takes care of user concerns around cross-browser compatibility. This is only possible with GTM if one utilizes certain tag and macro templates. The user must be cautious about cross-browser support for their scripts once they begin adding custom JavaScript themselves.

Updated on: 16-Jan-2023


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