WordPress at a glance
function is not described

WP_Widget::update() public WP 2.8.0

Updates a particular instance of a widget.

This function should check that $new_instance is set correctly. The newly-calculated value of $instance should be returned. If false is returned, the instance won't be saved/updated.

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

No Hooks.

Return

Array. Settings to save or bool false to cancel saving.

Usage

$WP_Widget = new WP_Widget();
$WP_Widget->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::update() WP 5.7.2

<?php
public function update( $new_instance, $old_instance ) {
	return $new_instance;
}