The method Open of XMLHttpRequest

Question

What's the difference between Sync and Async in the method open(method,url,async) in AJAX.

Answer 1

The difference is that Sync doesn't exist. Ignore it. I wrote a whole synchronous widget library five years ago, and I became a better programmer when I rewrote it :-) I mention jQuery in this sentence but my preference goes to YUI. Whatever you do, watch the videos on Yahoo Theater: basic and advanced Javascript, the trouble with Dom, everything. They rock.

Answer 2

If you pass true for the async parameter, the call will return right away and the next line of javascript will execute (before the HTTP request returns).

If you pass false, it will block until the HTTP call returns.