I am trying to make a filter in WordPress WooCommerse. The filter for products is located on the page where the products has been shown by shortcode. The code I have already made can’t filter the products by color, just show string “[Object object]” instead.
This is the code i tried to create filter:

`<?php
// Function to generate a filter form
function get_custom_attribute_filter_form( $attribute ) {
    $output = '<div id="custom-attribute-filter">';
    
    $taxonomy = 'pa_' . $attribute;
    
    if ( taxonomy_exists( $taxonomy ) ) {
        $terms = get_terms( array(
            'taxonomy' => $taxonomy,
            'hide_empty' => false, // Set to false to show all terms
        ) );
        
        if ( ! empty( $terms ) && ! is_wp_error( $terms ) ) {
            $output .= '<label for="filter-' . esc_attr( $attribute ) . '">' . ucfirst( $attribute ) . ':</label>';
            $output .= '<select id="filter-' . esc_attr( $attribute ) . '" name="' . esc_attr( $attribute ) . '">';
            $output .= '<option value="">' . __( 'All', 'text_domain' ) . '</option>';
            foreach ( $terms as $term ) {
                $output .= '<option value="' . esc_attr( $term->slug ) . '">' . esc_html( $term->name ) . '</option>';
            }
            $output .= '</select>';
        }
    }
    
    $output .= '</div>';
    $output .= '<div id="filtered-products"></div>'; // Container for filtered products
    
    return $output;
}

// Shortcode registration
function custom_attribute_filter_shortcode( $atts ) {
    $atts = shortcode_atts( array(
        'attribute' => 'color',
    ), $atts, 'custom_attribute_filter' );

    return get_custom_attribute_filter_form( $atts['attribute'] );
}
add_shortcode( 'custom_attribute_filter', 'custom_attribute_filter_shortcode' );

// Adding style and JavaScript
function custom_attribute_filter_scripts() {
    ?>
    <script type="text/javascript">
        document.addEventListener('DOMContentLoaded', function() {
            var select = document.querySelector('#custom-attribute-filter select');
            if (select) {
                select.addEventListener('change', function() {
                    var attribute = this.name;
                    var value = this.value;
                    var data = {
                        action: 'filter_products',
                        attribute: attribute,
                        value: value,
                    };
                    
                    jQuery.post('<?php echo admin_url('admin-ajax.php'); ?>', data, function(response) {
                        document.getElementById('filtered-products').innerHTML = response;
                    });
                });
            }
        });
    </script>
    <?php
}
add_action( 'wp_footer', 'custom_attribute_filter_scripts' );

// AJAX function to filter products
function ajax_filter_products() {
    $attribute = sanitize_text_field( $_POST['attribute'] );
    $value = sanitize_text_field( $_POST['value'] );

    $args = array(
        'post_type' => 'product',
        'posts_per_page' => -1,
        'meta_query' => array(
            array(
                'key' => '_visibility',
                'value' => 'visible',
                'compare' => '=',
            ),
        ),
    );

    if ( $value ) {
        $args['tax_query'] = array(
            array(
                'taxonomy' => 'pa_' . $attribute,
                'field'    => 'slug',
                'terms'    => $value,
            ),
        );
    }

    $query = new WP_Query( $args );

    ob_start(); // Start buffering the output

    if ( $query->have_posts() ) {
        while ( $query->have_posts() ) {
            $query->the_post();
            wc_get_template_part( 'content', 'product' );
        }
    } else {
        echo __( 'No products found', 'text_domain' );
    }

    $output = ob_get_clean(); // Finish buffering and save the output to a variable

    // Return the filter result as an AJAX response
    wp_send_json_success( $output );

    wp_die();
}
add_action( 'wp_ajax_filter_products', 'ajax_filter_products' );
add_action( 'wp_ajax_nopriv_filter_products', 'ajax_filter_products' );
?>`