AJAX requests Synchronous Vs Asynchronous

Question

Is there any difference in performance ( speed wise ) between a synchronize request and and asynchronous request?

What all are the reasons for using an asynchronous request??

Answer 1

You should mostly always use an asynchronous Ajax Request, in fact I know only about one place where a synchronous Ajax Request should be used which is if you're in an Ajax Request embedding a new JavaScript file on the client and then referencing types and/or objects from that JavaScript file in the return from the original Ajax Request. Then the fetching of this new JS file should (or can sanely) be included through using a synchronous Ajax Request...

Other then that you should always use asynchronous Ajax Requests. The most important reason is that a synchronous Ajax Request makes the UI (browser) unresponsive...

Answer 2

So, it's not a programmers mistake, the script engines should improve so that they allow user to interact with the page