Question

Let’s say I’m $.post()-ing an AJAX request to a script that does the following:

echo "foo";
sleep(60);  // block request for some time
echo "bar";

Will the originating script fire the success function when it sees “foo”, or when the ajax script is finally done after “bar” is echoed?

Answer 1

There may be several readystatechange events while the response arrives, but the readyState only changes to 4 (Loaded) when the response is complete.

The jQuery library will call the success method when a readystatechange event happens and the readyState property is 4 (Loaded), and status property shows a successful status code (e.g. 200).