How to Send Data to the DataLayer in WordPress

Introduction

In modern web analytics and marketing implementations, Google Tag Manager’s DataLayer plays a crucial role in decoupling data collection from tag deployment. If you run a WordPress site, learning how to send data to the DataLayer correctly will allow you to build robust tracking solutions—whether you’re capturing e-commerce events, custom form submissions, or user interactions. This comprehensive guide covers everything from basic concepts to advanced code snippets and best practices.

Understanding the DataLayer

What is the DataLayer

The DataLayer is a JavaScript array that collects structured data about user interactions and page context. It acts as a bridge between your website’s data and GTM tags. When you push information into the DataLayer, GTM can pick up those events or variables and fire tags accordingly.

Why Use the DataLayer

• Separation of Concerns: Keeps your presentation layer clean and your analytics logic centralized.
• Scalability: Easily add or modify variables without editing dozens of scripts.
• Consistency: Ensures that data is formatted the same way across different pages and interactions.

Setting Up Google Tag Manager in WordPress

Installing the GTM Container

1. Sign in to your GTM Account and create a container for your site.
2. Copy the provided ltscriptgt and ltnoscriptgt snippets.
3. In WordPress, paste the scripts into your theme’s header.php (immediately after the ltheadgt tag) and footer.php (after the opening ltbodygt tag) or use a plugin like GTM4WP.

Verification

Enable Preview Mode in GTM and confirm that the container loads on your site without errors. You should see the GTM debug console at the bottom of your pages.

Sending Data to the DataLayer

Basic Syntax

Use the following JavaScript snippet anywhere after GTM’s dataLayer declaration:

dataLayer.push({
  event: yourEventName,
  variable1: value1,
  variable2: value2
})

Where to Place the Code

• functions.php: Hook into wp_head or wp_footer to output inline scripts.
• Template Files: Inject code directly in page templates (e.g., page.php, single.php).
• JavaScript File: Enqueue a custom JS file via wp_enqueue_script.

Example: Pushing a Custom Event on Form Submission

document.getElementById(contact-form).addEventListener(submit, function(){
  dataLayer.push({
    event: contactFormSubmit,
    formId: contact-form
  })
})

E-commerce Tracking Example

Event	DataLayer Push
Add to Cart	dataLayer.push({ event:addToCart, ecommerce:{ currency:USD,value:29.99,items:[{id:SKU123,name:Product Name,quantity:1,price:29.99}]}})
Purchase	dataLayer.push({ event:purchase, ecommerce:{ transaction_id:T12345,value:59.98,currency:USD,items:[{id:SKU123,quantity:1,price:29.99},{id:SKU456,quantity:1,price:29.99}]}})

WordPress Plugins for DataLayer Management

GTM4WP (DuracellTomi)

This popular plugin not only injects the GTM container but provides dedicated hooks to push Page View events, WooCommerce events, form events, and more. Plugin Link.

Custom Code Snippet Plugin

If you prefer full control, use a snippet plugin (e.g., Code Snippets) to register concise actions in wp_head or wp_footer.

Best Practices

Naming Conventions

• Use camelCase for variable names (e.g., purchaseValue).
• Prefix custom events with your brand or project identifier (e.g., mySite_formSubmit).

Data Consistency

Ensure data types stay consistent: strings, numbers, booleans. Avoid pushing undefined or null values.

Security Considerations

Never push sensitive personal data (PII) such as full emails, names or payment details. Anonymize or hash information if needed.

Testing and Debugging

GTM Preview Debug Mode

Activate Preview Mode in GTM to see real-time DataLayer pushes and tag firings. Validate that your custom events appear under the Data Layer tab.

Browser Console

Open Developer Tools and type console.log(dataLayer) to inspect the array contents. You can also add console.log inside your push code for step-by-step verification.

Conclusion

Mastering how to send data to the DataLayer in WordPress empowers you to build scalable, maintainable, and accurate tracking implementations. Whether you leverage plugins or custom code, the key is consistent, well-structured pushes and diligent testing. For further reading, consult the GTM Developer Guide and the GTM Quickstart.