Custom event tracking in GA4 enables you to measure unique user interactions tailored to your osCommerce store—such as CTA clicks, form submissions, scroll depth, video plays, or custom button engagements.

In this guide, you’ll learn how to implement fully customized GA4 event tracking in osCommerce via Google Tag Manager.

🧰 Prerequisites

• ✅ Google Tag Manager installed across all osCommerce pages
• ✅ GA4 Configuration Tag created in GTM
• ✅ Access to osCommerce PHP/HTML templates
• ✅ Developer console or FTP for editing theme files

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📌 Common Use Cases for Custom Events in osCommerce

Event Name	Triggered On
cta_click	Click on “Register”, “Buy Now”, or banners
form_submit	Lead form or newsletter submission
scroll_80_percent	When user scrolls 80% of product page
chat_initiated	When user opens live chat
wishlist_add	When product is added to wishlist

🔧 Step 1: Plan Your Custom Events

Define the naming convention and parameters in a tracking plan.

Example: cta_click

Parameter	Value Example
link_text	“Register Now”
page_path	“/product_info.php?products_id=12”
cta_type	“Top Banner”

🖥️ Step 2: Add data-attributes or Custom Class to HTML

Modify CTA buttons in osCommerce to include a unique selector.

Example: In includes/modules/content/index/cm_index_products.php

<a href="register.php" class="btn btn-primary custom-cta" 
   data-cta-type="Top Banner" data-cta-text="Register Now">
   Register Now
</a>

🧠 Step 3: Create GTM Click Trigger for Custom CTA

1. Go to GTM → Triggers → New
2. Name: Click - CTA Button
3. Type: Click – All Elements
4. Trigger Conditions:
   • Click Classes → contains custom-cta

🔁 Step 4: Create Data Layer Push (optional for more control)

For dynamic events or JS-triggered actions, inject a dataLayer.push() using PHP or JavaScript:

Example for JS-triggered event:

<a href="register.php" onclick="dataLayer.push({
  event: 'cta_click',
  link_text: 'Register Now',
  cta_type: 'Top Banner',
  page_path: window.location.pathname
})" class="btn btn-primary">Register Now</a>

🏷️ Step 5: Create GA4 Event Tag in GTM

1. Go to Tags → New
2. Choose: GA4 Event
3. Configuration Tag: Select your GA4 config
4. Event Name: cta_click
5. Event Parameters:
   • link_text → {{Click Text}}
   • cta_type → {{Click Element - CTA Type}}
   • page_path → {{Page Path}}

🧪 Step 6: Define Custom Variables in GTM

1. Click Element – CTA Type
   • Type: DOM Element
   • Selector: Click Element
   • Attribute name: data-cta-type
2. Click Text
   • Built-in Variable → Enable Click Text

🧪 Step 7: Test in GTM Preview and GA4 DebugView

1. Enable GTM Preview Mode
2. Navigate to a page with the CTA
3. Click the button and ensure:
   • The custom event triggers in GTM
   • Event appears in GA4 DebugView

🔍 Step 8: View in GA4 Reports

Go to:

GA4 → Reports → Engagement → Events

You will see your event name cta_click. You can also create custom exploration reports or audiences using these parameters.

➕ Bonus: Track Scroll Depth or Other UX Events

Scroll Event Example using GTM Trigger:

1. Trigger type: Scroll Depth
2. Vertical Scroll Depths: 80
3. Fire once per page

Then tag with:

• Event name: scroll_80_percent
• Parameters: page_title, page_path

📌 Summary of Custom Event Implementation

Step	Action
1	Add unique HTML attributes or use JS for events
2	Use dataLayer.push() or click triggers in GTM
3	Create GA4 Event Tags mapped to your custom data
4	Test in GTM Preview and GA4 DebugView
5	Report & optimize based on custom engagement data

✅ Best Practices

• Follow GA4 naming conventions: lowercase, snake_case
• Use GTM Variables to dynamically pass values
• Combine with Enhanced Ecommerce for deeper funnel analysis
• Add triggers like form submit, video start, or live chat open

🚀 Final Thoughts

Custom event tracking in osCommerce using GTM and GA4 enables precise behavioral insights that go beyond standard ecommerce metrics. Whether you’re optimizing CTAs, forms, or scroll depth, these events become essential signals for conversion rate optimization, remarketing, and product strategy.

Want to go further? Add these events to your server-side GTM container for durable attribution!