register_sidebar example

$_args['id'] = $args['id'];
            $n           = 2; // Start at -2 for conflicting custom IDs.             while ( is_registered_sidebar( $_args['id'] ) ) {
                $_args['id'] = $args['id'] . '-' . $n++;
            }
        } else {
            $n = count( $wp_registered_sidebars );
            do {
                $_args['id'] = 'sidebar-' . ++$n;
            } while ( is_registered_sidebar( $_args['id'] ) );
        }
        register_sidebar( $_args );
    }
}

/** * Builds the definition for a single sidebar and returns the ID. * * Accepts either a string or an array and then parses that against a set * of default arguments for the new sidebar. WordPress will automatically * generate a sidebar ID and name based on the current number of registered * sidebars if those arguments are not included. * * When allowing for automatic generation of the name and ID parameters, keep * in mind that the incrementor for your sidebar can change over time depending * on what other plugins and themes are installed. * * If theme support for 'widgets' has not yet been added when this function is * called, it will be automatically enabled through the use of add_theme_support() * * @since 2.2.0 * @since 5.6.0 Added the `before_sidebar` and `after_sidebar` arguments. * @since 5.9.0 Added the `show_in_rest` argument. * * @global array $wp_registered_sidebars Registered sidebars. * * @param array|string $args { * Optional. Array or string of arguments for the sidebar being registered. * * @type string $name The name or title of the sidebar displayed in the Widgets * interface. Default 'Sidebar $instance'. * @type string $id The unique identifier by which the sidebar will be called. * Default 'sidebar-$instance'. * @type string $description Description of the sidebar, displayed in the Widgets interface. * Default empty string. * @type string $class Extra CSS class to assign to the sidebar in the Widgets interface. * Default empty. * @type string $before_widget HTML content to prepend to each widget's HTML output when assigned * to this sidebar. Receives the widget's ID attribute as `%1$s` * and class name as `%2$s`. Default is an opening list item element. * @type string $after_widget HTML content to append to each widget's HTML output when assigned * to this sidebar. Default is a closing list item element. * @type string $before_title HTML content to prepend to the sidebar title when displayed. * Default is an opening h2 element. * @type string $after_title HTML content to append to the sidebar title when displayed. * Default is a closing h2 element. * @type string $before_sidebar HTML content to prepend to the sidebar when displayed. * Receives the `$id` argument as `%1$s` and `$class` as `%2$s`. * Outputs after the {@see 'dynamic_sidebar_before'} action. * Default empty string. * @type string $after_sidebar HTML content to append to the sidebar when displayed. * Outputs before the {@see 'dynamic_sidebar_after'} action. * Default empty string. * @type bool $show_in_rest Whether to show this sidebar publicly in the REST API. * Defaults to only showing the sidebar to administrator users. * } * @return string Sidebar ID added to $wp_registered_sidebars global. */

if ( empty( $sidebars_widgets ) ) {
    $sidebars_widgets = wp_get_widget_defaults();
}

foreach ( $sidebars_widgets as $sidebar_id => $widgets ) {
    if ( 'wp_inactive_widgets' === $sidebar_id ) {
        continue;
    }

    if ( ! is_registered_sidebar( $sidebar_id ) ) {
        if ( ! empty( $widgets ) ) { // Register the inactive_widgets area as sidebar.             register_sidebar(
                array(
                    'name'          => __( 'Inactive Sidebar (not used)' ),
                    'id'            => $sidebar_id,
                    'class'         => 'inactive-sidebar orphan-sidebar',
                    'description'   => __( 'This sidebar is no longer available and does not show anywhere on your site. Remove each of the widgets below to fully remove this inactive sidebar.' ),
                    'before_widget' => '',
                    'after_widget'  => '',
                    'before_title'  => '',
                    'after_title'   => '',
                )
            );
        }

/** * Registers widget area. * * @since Twenty Twenty-One 1.0 * * @link https://developer.wordpress.org/themes/functionality/sidebars/#registering-a-sidebar * * @return void */
function twenty_twenty_one_widgets_init() {

    register_sidebar(
        array(
            'name'          => esc_html__( 'Footer', 'twentytwentyone' ),
            'id'            => 'sidebar-1',
            'description'   => esc_html__( 'Add widgets here to appear in your footer.', 'twentytwentyone' ),
            'before_widget' => '<section id="%1$s" class="widget %2$s">',
            'after_widget'  => '</section>',
            'before_title'  => '<h2 class="widget-title">',
            'after_title'   => '</h2>',
        )
    );
}