WordPress at a glance
function is not described

WP_Customize_Custom_CSS_Setting::preview() public WP 4.7.9

Add filter to preview post value.

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

No Hooks.

Return

true|false. False when preview short-circuits due no change needing to be previewed.

Usage

$WP_Customize_Custom_CSS_Setting = new WP_Customize_Custom_CSS_Setting();
$WP_Customize_Custom_CSS_Setting->preview();

Changelog

Since 4.7.9 Introduced.

Code of WP_Customize_Custom_CSS_Setting::preview() WP 5.7.2

<?php
public function preview() {
	if ( $this->is_previewed ) {
		return false;
	}
	$this->is_previewed = true;
	add_filter( 'wp_get_custom_css', array( $this, 'filter_previewed_wp_get_custom_css' ), 9, 2 );
	return true;
}