Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user’s experience. For more help https://xhr.spec.whatwg.org/#sync-warning
Сінхронны XMLHttpRequest у галоўным патоку састарэў, бо мае шкодны ўплыў на досвед карыстальніка. Падрабязней на https://xhr.spec.whatwg.org/#sync-warning