Add toggle button to ACF flexible fields

ACF toggle btn flexible functions.php

function acf_toggle_flex()
{

?>
    <script type="text/javascript">
        (function($) {
            acf.add_action('load', function($el) {

                let $field = $el.find('.acf-field-flexible-content'); // Get flexabile fields
                $field = Array.prototype.slice.call($field); // Convert to array

                $field.forEach(function(container) { // Loop through all fields on the page

                    // Create button
                    let btn = document.createElement("a");
                    btn.classList.add('button', 'button-primary', 'toggle-flex-fields');
                    btn.innerText = 'Toggle';

                    // Prepend button on top of the container
                    container.prepend(btn);

                    // Get toggleable fields
                    const item = container.querySelectorAll(".layout");

                    // Add click event to button
                    btn.addEventListener('click', function(event) {
                        event.preventDefault();
                        item.forEach(function(item) {
                            item.classList.toggle('-collapsed')
                        });
                    });

                });
            });

        })(jQuery);
    </script>
<?php

}

add_action('acf/input/admin_footer', 'acf_toggle_flex');