Variable types for web pages

1st party cookie: The value is set to the 1st party cookie with the matching name for domain that the user is currently on. In the case that a cookie with same name is deployed on multiple paths or multiple levels of domain within the same domain, the first value will be chosen. This is the same is if you had called document.cookie from within a page and chosen the first result.

Constant String: The value is set to the string you provide. Since this string will always be the same, and is simply the string that you provide here, the Constant String variable type is limited in usefulness. However, if you want to set a standard company name across your site, for example, you could define it as a Constant String type variable. This would allow you to easily update the string in Google Tag Manager and see it reflected across all the tags that use this variable.

Container Version Number: When the container is in preview mode, the container version variable returns the container's preview version number. Otherwise, this variable returns the container's live version number.

Custom JavaScript: The value is set to the result of a JavaScript function. The JavaScript must take the form of an anonymous function that returns a value. For example, you could write a custom JavaScript variable called "lowerUrl" that operates on the predefined {{url}} variable:

function () {
  return {{url}}.toLowerCase();

Data Layer: The value is set to ‘value’ when the following code on your website is executed: dataLayer.push({'Data Layer Name': 'value'})

You can specify, in Google Tag Manager, how dots ('.') are to be interpreted in the data layer variable name:

  • Version 1: allow dots in key names. For example, for dataLayer.push('a.b.c': 'value'), interpret the name of the key as "a.b.c" (i.e. {'a.b.c': 'value'}).
  • Version 2: interpret dots as nested values. For example, interpret dataLayer.push({'a.b.c': 'value'}) as three nested levels: {a: {b: {c: 'value'}}}. This allows you to read nested values; you could set the variable name to 'a.b' and it would return the object {c: 'value'} (according to standard JavaScript rules). Nested pushing also allows you to directly edit nested values, so executing:
    dataLayer.push({'a.b.c': 'value'});
    dataLayer.push({'a.b.d': 4});

    on your page would result in a dataLayer that looks like {a: {b: {c: 'value', d: 4}}}.

Debug Mode: The value is set to true if the container is being viewed in debug mode.

DOM Element: The value is set to the text of the DOM (Document Object Model) element or the value of the specified DOM element attribute. If the value you're looking for was not set up in the data layer (see Data Layer variable type, above), it's possible that the value can be retrieved from the DOM. Use this variable type if you can find the value you're looking for in the DOM by entering the value of the element's ID attribute.

If the optional attribute name is set, the variable's value will return the value specified from that attribute (e.g. data-food="cupcakes"); otherwise, the variable's value will be the text within the DOM element.

Element Visibility: The value is set based on the visible state of the specified DOM element. Unlike the Element Visibility trigger, a single Element Visibility variable can only report the visibility of a single element. Choose whether to select an element based on the element ID or a CSS Selector. If multiple elements are matched by a specified CSS Selector, the first matched element will be used.

You can choose the output type for this variable:

  • True / False: A boolean value indicating whether the selected element is visible when the variable is referenced. 
  • Percent: A numeric value (0-100) indicating how much of the selected element is visible on screen when the variable is referenced.

If you select “True / False” as the output type, you can also specify a Minimum Percent Visible to indicate how much of the selected element must be visible on screen for the variable to return true.

HTTP Referrer: The value is set to the HTTP referrer, the previous page that the person visited. For example, if a person navigates to one of your product pages from the home page, the referrer will be the home page. An instance of this variable type is automatically created by Google Tag Manager but you can create additional instances if you would like to have expose different part(s) of the referrer URL.

JavaScript Variable: The value is set to that of the global variable you specify. If the value you're looking for was not set up in the data layer (see Data Layer variable type), and it's not visible in the DOM (see DOM Element variable types), it's possible that the value can be retrieved from a JavaScript variable. Use this variable type if you can find the value you're looking for in the source of the page in the form of a JavaScript variable.

Lookup Table: The value is set according to the instructions in the lookup table. The lookup table contains two columns (Table empty to illustrate how data is used later):

When [select variable] equals Set [this variable] to

The Lookup Table type allows you to create a variable for which the value varies according to the value in another variable. This is useful if your website is set up in such a way that the appropriate value (for example, a conversion tracking ID) can be mapped to the URL or another aspect of the page. In this example, a variable named Conversion ID is being created. If the URL is “/thanks/buy1.html”, the value is set to “12345”; if the URL is “thanks/buy2.html”, the value is set to “34567”. There is no limit to the number of rows in the lookup table. Fields are case sensitive.

When {{url}} equals Set {{Conversion ID}} to 12345 34567 56789

Random number: The value is set to a random number between 0 and 2147483647.

RegEx Table: A RegEx Table variable works similarly to Lookup Tables, with the addition of being able to run regular expression patterns for the items you want to match.

To illustrate how this works, consider the following RegEx Table settings:

Pattern Output
.*/page[1-3]\.html.* foo
.*/page[4-6]\.html.* bar
.*/page[7-9]\.html.* baz

The output value of the variable will be as follows: foo foo foo bar bar bar baz

RegEx Table lookups run from the top of the list to the bottom. When a match is found, the corresponding output value is returned.

Select Set Default Value to set an output value for when a match is not found.

By default, patterns must match the full input string and are case insensitive. This behavior can be adjusted in Advanced Settings:

  • Ignore Case: Patterns will match upper and lower case matches without having to build this into the regular expression explicitly.

  • Full Matches Only: If enabled, patterns must match entire input. This is equivalent to having start (^) and end ($) anchors implicitly around your pattern. If disabled, patterns will match when they are found anywhere in the input. Disabling this option may cause unexpected behavior with "Capture Groups and Replace Functionality".

  • Capture Groups and Replace Functionality: If enabled, you can use dollar-sign replacement syntax to include portions of the input (e.g. from capturing groups in the matched pattern) within the output. For example, if the matched regular expression is /(news)/page(2)\.html, you can use $1 to reference the first capture group ("news") and $2 to reference the second capture group ("2").

    Using "Capture Groups and Replace Functionality" with "Full Matches Only" disabled may result in unexpected behavior (i.e. returning the entire input value with the matched portion replaced).

URL: This type of variable allows you to parse and expose URL components. Google Tag Manager automatically creates 3 instances of this variable type (full url, hostname and path). You can create additional instances to expose different parts of the URL. The URL components you can choose from are: Protocol, Hostname, Port, Path, Query, and Fragment. The input value set for variables of this type is the url of the current page the user is on (retrieved from document.location). By adjusting the URL Source setting, it is possible to tell Google Tag Manager to use another variable as the source of the url value.

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