public function widget( $args, $instance ) {
    static $first_dropdown = true;

    $default_title = __( 'Categories' );
    $title         = ! empty( $instance['title'] ) ? $instance['title'] : $default_title;

    
/** This filter is documented in wp-includes/widgets/class-wp-widget-pages.php */
    $title = apply_filters( 'widget_title', $title, $instance, $this->id_base );

    $count        = ! empty( $instance['count'] ) ? '1' : '0';
    $hierarchical = ! empty( $instance['hierarchical'] ) ? '1' : '0';
    $dropdown     = ! empty( $instance['dropdown'] ) ? '1' : '0';

    echo $args['before_widget'];

    if ( $title ) {
      echo $args['before_title'] . $title . $args['after_title'];
    }

    $cat_args = array(
      'orderby'      => 'name',
      'show_count'   => $count,
      'hierarchical' => $hierarchical,
    );

    if ( $dropdown ) {
      printf( '<form action="%s" method="get">', esc_url( home_url() ) );
      $dropdown_id    = ( $first_dropdown ) ? 'cat' : "{$this->id_base}-dropdown-{$this->number}";
      $first_dropdown = false;

      echo '<label class="screen-reader-text" for="' . esc_attr( $dropdown_id ) . '">' . $title . '</label>';

      $cat_args['show_option_none'] = __( 'Select Category' );
      $cat_args['id']               = $dropdown_id;

      
/**
 * Filters the arguments for the Categories widget drop-down.
 *
 * @since 2.8.0
 * @since 4.9.0 Added the `$instance` parameter.
 *
 * @see wp_dropdown_categories()
 *
 * @param array $cat_args An array of Categories widget drop-down arguments.
 * @param array $instance Array of settings for the current widget.
 */
      wp_dropdown_categories( apply_filters( 'widget_categories_dropdown_args', $cat_args, $instance ) );

      echo '</form>';

      ob_start();
      ?>

<script>
(function() {
	var dropdown = document.getElementById( "<?php echo esc_js( $dropdown_id ); ?>" );
	function onCatChange() {
		if ( dropdown.options[ dropdown.selectedIndex ].value > 0 ) {
			dropdown.parentNode.submit();
		}
	}
	dropdown.onchange = onCatChange;
})();
</script>

			<?php
      wp_print_inline_script_tag( wp_remove_surrounding_empty_script_tags( ob_get_clean() ) );
    } else {
      $format = current_theme_supports( 'html5', 'navigation-widgets' ) ? 'html5' : 'xhtml';

      
/** This filter is documented in wp-includes/widgets/class-wp-nav-menu-widget.php */
      $format = apply_filters( 'navigation_widgets_format', $format );

      if ( 'html5' === $format ) {
        // The title may be filtered: Strip out HTML and make sure the aria-label is never empty.
        $title      = trim( strip_tags( $title ) );
        $aria_label = $title ? $title : $default_title;
        echo '<nav aria-label="' . esc_attr( $aria_label ) . '">';
      }
      ?>

			<ul>
				<?php
        $cat_args['title_li'] = '';

        
/**
 * Filters the arguments for the Categories widget.
 *
 * @since 2.8.0
 * @since 4.9.0 Added the `$instance` parameter.
 *
 * @param array $cat_args An array of Categories widget options.
 * @param array $instance Array of settings for the current widget.
 */
        wp_list_categories( apply_filters( 'widget_categories_args', $cat_args, $instance ) );
        ?>
			</ul>

			<?php
      if ( 'html5' === $format ) {
        echo '</nav>';
      }
    }

    echo $args['after_widget'];
  }