Main Product Image code

I tried this code to print the photo contained in the variation image as the main product image, but it doesn’t work. Anyone can help me? Thank in advance!

// Aggiungi script JavaScript personalizzato
function custom_wc_product_image_script() {
    // Verifica se siamo sulla pagina del singolo prodotto WooCommerce
    if (is_product()) { 
        // Output del codice JavaScript
        ?>
        <script type="text/javascript">
            document.addEventListener("DOMContentLoaded", function() {
                var selectedSwatch = document.querySelector('.cfvsw-selected-swatch');
                var imageUrl = selectedSwatch.querySelector('.cfvsw-swatch-inner').style.backgroundImage;
                imageUrl = imageUrl.replace('url(','').replace(')','').replace(/\"/gi, "");
                var mainProductImage = document.querySelector('.woocommerce div.product div.images .woocommerce-product-gallery__image img');
                mainProductImage.setAttribute('src', imageUrl);
            });
        </script>
        <?php
    }
}
add_action('wp_footer', 'custom_wc_product_image_script');