zouip

jsonp is precisely based on the use of the src attribute. Of course for locally calls one should use an XMLHttpRequest object (in certain cases though the <script> pattern may be more appropriate (long polling requests is an example)).

You can do AJAX without any XMLHttpRequest object. Instead, you can use an other data transportation pattern: dynamically loaded javascript thanks to the 'script' tag and its 'src' attribute. This transportation pattern is usually associated with the JSON format (even though you can wrap XML as well) and it is sometimes considered as more powerfull than the XMLHTTPRequest object since it allows AJAX applications to perform cross-domain requests. Some service providers such as Google or Yahoo use this pattern thus making it possible to establish connections to their servers inside your AJAX application. There are tones of articles that tackle this subject on the internet. Google is your friend.

This syntax is totally legal and such a script object can be used to perform asynchronous http requests as well as an xmlhttprequest can do.