Craft\NeoService::isPreviewMode PHP Method

    public function isPreviewMode()
    {
        if (craft()->request->isLivePreview()) {
            return true;
        }
        $token = craft()->request->getParam('token');
        if ($token) {
            $route = craft()->tokens->getTokenRoute($token);
            // If an entry draft is being previewed, use the content stored in the draft
            if ($route && $route['action'] == 'entries/viewSharedEntry') {
                return true;
            }
        }
        return false;
    }