WordPress at a glance
function is not described

WP_Customize_Manager::is_theme_active() public WP 3.4.0

Checks if the current theme is active.

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

No Hooks.

Return

true|false.

Usage

$WP_Customize_Manager = new WP_Customize_Manager();
$WP_Customize_Manager->is_theme_active();

Changelog

Since 3.4.0 Introduced.

Code of WP_Customize_Manager::is_theme_active() WP 5.7.2

<?php
public function is_theme_active() {
	return $this->get_stylesheet() === $this->original_stylesheet;
}