Improving handling of add_to_cart and other Woo events

[jamesozzie]

Bug Description

A couple of users reported possible conflicts or issues with our WooCommerce add_to_cart events. These are highlighted below:

• Uncaught TypeError: Cannot read properties of undefined (reading ‘data’) | SH info | Topic | Task
• Uncaught TypeError: Cannot read properties of null (reading ‘data’) | Awaiting SH info | Topic | Task

One user provided very valuable insights into their findings, found here.

After the first report, we discussed scope for improvement with the data property for add_to_cart events. This GitHub issue is to review and provide such improvements to reduce the liklihood of errors reported by users.

Additional Context

• Reported since Site Kit 1.159.0

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Acceptance criteria

• The reported JavaScript error should not occur while using Site Kit's plugin conversion tracking with WooCommerce at any point.
• When using Site Kit's plugin conversion tracking, add to cart events in WooCommerce should be correctly tracked for all types of products (e.g. simple, variable, etc).
• If, for any reason, the event cannot be tracked (e.g. when WooCommerce is customised by the theme or third-party integrations), no JavaScript error should be raised.

Implementation Brief

• [x] Update the WooCommerce event provider in assets/js/event-providers/woocommerce.js
  • [x] In the added_to_cart listener, return early if the $button argument is not an actual jQuery element instance

Test Coverage

QA Brief

Test base functionality:

• Navigate to a WooCommerce shop page with simple products
• Open browser developer console (F12 → Console tab)
• Click "Add to Cart" on a simple product
• Verify no JavaScript errors appear in the console
• Verify the add_to_cart event is tracked (check Network tab for gtag requests or use Google Analytics DebugView)

Test again on the sites/setups described in the issue description. Confirm no JavaScript errors occur.

Changelog entry

• Fix handling of add_to_cart and other WooCommerce events.

[nfmohit]

I've downgraded this to a P1 as this doesn't appear to happen with a default WooCommerce setup, but it can happen when the DOM is customised by the theme or third-party WooCommerce integrations.

[eugene-manuilov]

@abdelmalekkkkk, did you forget to save your changes?

[abdelmalekkkkk]

@eugene-manuilov Yep it seemed like it didn't go through. Should be good now.

[eugene-manuilov]

IB ✔️