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()

$args array|string Optional

Array or string of arguments for the sidebar being registered.

• namestring
  The name or title of the sidebar displayed in the Widgets interface. Default 'Sidebar $instance'.
• idstring
  The unique identifier by which the sidebar will be called.
  Default 'sidebar-$instance'.
• descriptionstring
  Description of the sidebar, displayed in the Widgets interface.
  Default empty string.
• classstring
  Extra CSS class to assign to the sidebar in the Widgets interface.
  
• before_widgetstring
  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.
• after_widgetstring
  HTML content to append to each widget's HTML output when assigned to this sidebar. Default is a closing list item element.
• before_titlestring
  HTML content to prepend to the sidebar title when displayed.
  Default is an opening h2 element.
• after_titlestring
  HTML content to append to the sidebar title when displayed.
  Default is a closing h2 element.
• before_sidebarstring
  HTML content to prepend to the sidebar when displayed.
  Receives the $id argument as %1$s and $class as %2$s.
  Outputs after the 'dynamic_sidebar_before' action.
  Default empty string.
• after_sidebarstring
  HTML content to append to the sidebar when displayed.
  Outputs before the 'dynamic_sidebar_after' action.
  Default empty string.
• show_in_restbool
  Whether to show this sidebar publicly in the REST API.
  Defaults to only showing the sidebar to administrator users.

Default: array()

string Sidebar ID added to $wp_registered_sidebars global.

File: wp-includes/widgets.php. View all references

function register_sidebar( $args = array() ) {
	global $wp_registered_sidebars;

	$i = count( $wp_registered_sidebars ) + 1;

	$id_is_empty = empty( $args['id'] );

	$defaults = array(
		/* translators: %d: Sidebar number. */
		'name'           => sprintf( __( 'Sidebar %d' ), $i ),
		'id'             => "sidebar-$i",
		'description'    => '',
		'class'          => '',
		'before_widget'  => '<li id="%1$s" class="widget %2$s">',
		'after_widget'   => "</li>\n",
		'before_title'   => '<h2 class="widgettitle">',
		'after_title'    => "</h2>\n",
		'before_sidebar' => '',
		'after_sidebar'  => '',
		'show_in_rest'   => false,
	);

	/**
	 * Filters the sidebar default arguments.
	 *
	 * @since 5.3.0
	 *
	 * @see register_sidebar()
	 *
	 * @param array $defaults The default sidebar arguments.
	 */
	$sidebar = wp_parse_args( $args, apply_filters( 'register_sidebar_defaults', $defaults ) );

	if ( $id_is_empty ) {
		_doing_it_wrong(
			__FUNCTION__,
			sprintf(
				/* translators: 1: The 'id' argument, 2: Sidebar name, 3: Recommended 'id' value. */
				__( 'No %1$s was set in the arguments array for the "%2$s" sidebar. Defaulting to "%3$s". Manually set the %1$s to "%3$s" to silence this notice and keep existing sidebar content.' ),
				'<code>id</code>',
				$sidebar['name'],
				$sidebar['id']
			),
			'4.2.0'
		);
	}

	$wp_registered_sidebars[ $sidebar['id'] ] = $sidebar;

	add_theme_support( 'widgets' );

	/**
	 * Fires once a sidebar has been registered.
	 *
	 * @since 3.0.0
	 *
	 * @param array $sidebar Parsed arguments for the registered sidebar.
	 */
	do_action( 'register_sidebar', $sidebar );

	return $sidebar['id'];
}