Add aria-label to wp_dropdown_categories()

wp-dropdown-categories-accessibility.php

<?php
/**
 * If the aria-label argument has been specified in a wp_dropdown_categories() call,
 * output the aria-label option in the <select>
 *
 * @since   1.0.0
 *
 * @param   string  $output     HTML Output
 * @param   array   $arguments  wp_dropdown_category() arguments
 * @return  string              Modified HTML Output
 */
public function wp_dropdown_cats_aria_label_support( $output, $arguments ) {

    // Bail if no aria-label argument has been supplied
    if ( ! isset( $arguments['aria-label'] ) ) {
        return $output;
    }

    // Add aria-label
    $output = str_replace( '<select ', '<select aria-label="' . sanitize_text_field( $arguments['aria-label'] ) . '"', $output );

    // Return
    return $output;

}
add_filter( 'wp_dropdown_cats', 'wp_dropdown_cats_aria_label_support', 10, 2 );

wp-dropdown-categories-usage.php

<?php
/**
 * Example usage of wp_dropdown_categories(), when aria-label
 * support has been added.
 *
 * @since   1.0.0
 */
wp_dropdown_categories( array(
  // Other wp_dropdown_categories() arguments go here...
  
  // Define our aria-label
  'aria-label' => __( 'ARIA Label Value', 'domain' ),
) );