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
主线程中同步的 XMLHttpRequest 已弃用，因其对终端用户的用户体验存在负面影响。可访问 https://xhr.spec.whatwg.org/#sync-warning 详细了解