wp_render_widget() WordPress Function

function wp_render_widget( $widget_id, $sidebar_id ) {
	global $wp_registered_widgets, $wp_registered_sidebars;

	if ( ! isset( $wp_registered_widgets[ $widget_id ] ) ) {
		return '';
	}

	if ( isset( $wp_registered_sidebars[ $sidebar_id ] ) ) {
		$sidebar = $wp_registered_sidebars[ $sidebar_id ];
	} elseif ( 'wp_inactive_widgets' === $sidebar_id ) {
		$sidebar = array();
	} else {
		return '';
	}

	$params = array_merge(
		array(
			array_merge(
				$sidebar,
				array(
					'widget_id'   => $widget_id,
					'widget_name' => $wp_registered_widgets[ $widget_id ]['name'],
				)
			),
		),
		(array) $wp_registered_widgets[ $widget_id ]['params']
	);

	// Substitute HTML `id` and `class` attributes into `before_widget`.
	$classname_ = '';
	foreach ( (array) $wp_registered_widgets[ $widget_id ]['classname'] as $cn ) {
		if ( is_string( $cn ) ) {
			$classname_ .= '_' . $cn;
		} elseif ( is_object( $cn ) ) {
			$classname_ .= '_' . get_class( $cn );
		}
	}
	$classname_                 = ltrim( $classname_, '_' );
	$params[0]['before_widget'] = sprintf( $params[0]['before_widget'], $widget_id, $classname_ );

	/** This filter is documented in wp-includes/widgets.php */
	$params = apply_filters( 'dynamic_sidebar_params', $params );

	$callback = $wp_registered_widgets[ $widget_id ]['callback'];

	ob_start();

	/** This filter is documented in wp-includes/widgets.php */
	do_action( 'dynamic_sidebar', $wp_registered_widgets[ $widget_id ] );

	if ( is_callable( $callback ) ) {
		call_user_func_array( $callback, $params );
	}

	return ob_get_clean();
}