Avoid loading checkout inside full-page iframe or allow proper URL navigation

[jitman]

The plugin currently handles the /fb-checkout route by rendering the WooCommerce checkout page inside a full-screen <iframe> rather than performing a standard redirect. This approach causes several UX, technical, and compatibility issues.

facebook-for-woocommerce/includes/Checkout.php

Line 216 in 19c0808

<iframe src="' . esc_url( $checkout_url ) . '"></iframe>

Steps to Reproduce

1. Install and activate the Facebook for WooCommerce plugin, set up with Meta Commerce account
2. Build a test checkout URL formatted as: /fb-checkout?products={...}&coupon={...}.
3. Upon code inspection, observe that the page loads an HTML wrapper with an <iframe> pointing to the checkout URL.

Current Behavior

• The entire checkout experience is embedded inside an <iframe>.
• The browser’s address bar remains fixed at /fb-checkout, even as users progress through the checkout flow.
• Navigating elsewhere or refreshing causes confusion because the URL does not reflect the current page state.

Expected Behavior

• Users should be redirected to the normal WooCommerce checkout URL after the cart is rebuilt, not shown within an <iframe>.
• Alternatively, if the iframe is required for specific integrations, the plugin should:
• Allow URL updates (pushState or redirect) when navigating to checkout or order confirmation.
• Provide a filter or setting to disable iframe wrapping.

Issues with Current Implementation

1. Session and Cookie Problems - Some browsers restrict cookies and local storage in iframe contexts, leading to lost sessions or failed payments.
2. Payment Gateway Incompatibility - Payment methods could fail or are blocked in iframes.
3. Analytics and Conversion Tracking - Conversion tracking scripts may not fire correctly in iframes.
4. Poor UX - URL never changes, confusing users and breaking bookmarks, refreshes, and the back button.
5. Accessibility and SEO - Screen readers and accessibility tools struggle with iframe-wrapped pages.

Proposed Solutions

1. Preferred: Replace the iframe output with a direct redirect to wc_get_checkout_url() after rebuilding the cart and applying coupons.
2. Alternative: Introduce a filter or option to disable iframe embedding while keeping the cart-rebuilding logic intact.
3. Minimal: Update browser history (via window.history.pushState) to reflect the actual checkout URL inside the iframe.

Environment

• WordPress: 6.8.3
• WooCommerce: 10.2.2
• Facebook for WooCommerce: 3.5.9
• Browser: Brave (Chromium) / Safari (issues reproducible on all)