Archive for October, 2006

IE7 adds native XMLHTTPRequest object

Thursday, October 26th, 2006

The recently released IE7 supports a native XMLHTTPRequest object. On the surface this can be considered a good thing and should be commended. However, to the people that erroneously (in hindsight) assumed that…

window.XMLHttpRequest == ! (not) IE

…they are in for some strange behavior (here, here, here, and here for example).

The problem occurs when the code is optimized for non-IE browsers and does not recreate the XMLHTTPRequest object on each event. Back when “window.XMLHttpRequest == !IE” was true, this code worked as expected: IE browsers created a new XMLHttpRequest object on each event and non-IE browsers reused the same XMLHttpRequest object. Now IE7 will correctly process the first event but then fails on the second (and subsequent) requests because you still can’t reuse XMLHttpRequest objects.

We chose to just remove the optimization all together and recreate the object on each event for all browsers. Others may wish to come up with some other check that will allow them to keep it.

Posted in ajax | 7 Comments »