XMLHttpRequest on the main thread is deprecated

Question

What meaning of this message:

Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience. For more help, check http://xhr.spec.whatwg.org/ .

You may have a new message that will block any feature of my site?

Thanks

Answer 1

Apparently this message is displayed when using a synchronous AJAX request. Synchronous XMLHttpRequest on the main thread is deprecated

Answer 2

If you use a synchronous ajax request on the main thread it will block your application / webpage until the response is received.

You should use asynchronous requests with callbacks or use Worker-Threads to load the data with XMLHttpRequest. Normally the first solution is the prefered way.