Add WooCommerce Product Type Body Classes

/**
 * Add product type-specific CSS classes to the body element.
 *
 * This snippet appends custom body classes to WooCommerce
 * single product pages based on the product type, allowing
 * targeted styling and functionality for different product types.
 *
 * Added Classes:
 * - is-downloadable-product
 * - is-variable-product
 * - is-grouped-product
 * - is-external-product
 * - is-simple-product
 *
 */
function sj_add_product_type_body_class( $classes ) {

    // Check if the current page is a single product page.
    if ( is_singular( 'product' ) ) {

        // Get the current WooCommerce product object.
        $product = wc_get_product( get_the_ID() );

        // Verify that the product exists.
        if ( $product ) {

            $product_type = $product->get_type();

            // Add class for downloadable products.
            if ( $product->is_downloadable() ) {

                $classes[] = 'is-downloadable-product';

            // Add class for variable products.
            } elseif ( 'variable' === $product_type ) {

                $classes[] = 'is-variable-product';

            // Add class for grouped products.
            } elseif ( 'grouped' === $product_type ) {

                $classes[] = 'is-grouped-product';

            // Add class for external products.
            } elseif ( 'external' === $product_type ) {

                $classes[] = 'is-external-product';

            // Add class for simple products.
            } else {

                $classes[] = 'is-simple-product';
            }
        }
    }

    return $classes;
}

add_filter( 'body_class', 'sj_add_product_type_body_class' );