WordPress at a glance
function is not described

WP_Widget_Pages::update() public WP 2.8.0

Handles updating settings for the current Pages widget instance.

{} It's a method of the class: WP_Widget_Pages{}

No Hooks.

Return

Array. Updated settings to save.

Usage

$WP_Widget_Pages = new WP_Widget_Pages();
$WP_Widget_Pages->update( $new_instance, $old_instance );
$new_instance(array) (required)
New settings for this instance as input by the user via WP_Widget::form().
$old_instance(array) (required)
Old settings for this instance.

Changelog

Since 2.8.0 Introduced.

Code of WP_Widget_Pages::update() WP 5.7.2

<?php
public function update( $new_instance, $old_instance ) {
	$instance          = $old_instance;
	$instance['title'] = sanitize_text_field( $new_instance['title'] );
	if ( in_array( $new_instance['sortby'], array( 'post_title', 'menu_order', 'ID' ), true ) ) {
		$instance['sortby'] = $new_instance['sortby'];
	} else {
		$instance['sortby'] = 'menu_order';
	}

	$instance['exclude'] = sanitize_text_field( $new_instance['exclude'] );

	return $instance;
}