为什么Javascript异步检索数据（ajax，...）而PHP同步（mysql_query）？

Question

Why don't both retrieve them sychronously or both asynchronously? Or, better yet, why is it not vice-versa?

Answer 1

AJAX works asynchronously because it's normally used in an interactive application, the web browser. This allows the browser to be responsive to other user actions while it's waiting for a response.

PHP runs on the server, and doesn't directly interact with the user. So there's usually nothing else it could be doing while waiting for a response to a network request.