timezone.php

См. документацию.

<?php

namespace Bitrix\Main\Controller;
 
use Bitrix\Main;
 
class Timezone extends Main\Engine\Controller
{
    public function setAction(string $timezone)
    {
        global $USER;
 
        try
        {
            new \DateTimeZone($timezone);
        }
        catch (\Throwable)
        {
            $this->addError(new Main\Error("Incorrect timezone.", "ERR_PARAMS"));
            return null;
        }
 
        $USER->Update(
            $USER->GetID(),
            [
                "TIME_ZONE" => $timezone,
                "TIME_ZONE_OFFSET" => \CTimeZone::calculateOffset($timezone),
            ]
        );
 
        // remember in the current session
        $USER->SetParam("TIME_ZONE", $timezone);
 
        return true;
    }
}