Piwik\Plugins\API\Renderer\Json::getJsonpCallback PHP Method

    private function getJsonpCallback()
    {
        $jsonCallback = Common::getRequestVar('callback', false, null, $this->request);
        if ($jsonCallback === false) {
            $jsonCallback = Common::getRequestVar('jsoncallback', false, null, $this->request);
        }
        return $jsonCallback;
    }