calling abort method on XMLHttpRequest instance fires onreadystatechange with readyState 4

I was running some tests on how the different implementations of 
XMLHttpRequest in different browsers react on calling the abort method.

This test case
<http://home.arcor.de/martin.honnen/mozillaBugs/XMLHttpRequest/abortChangesReadyState4.html>
has a HTML form allowing you to select a readyState when to call abort 
on an XMLHttpRequest instance and to run the test by clicking the button.

Mozilla (both Firefox 1.5.0.1 and a Firefox trunk nightly (Mozilla/5.0 
(Windows; U; Windows NT 5.1; en-US; rv:1.9a1) Gecko/20060331 
Firefox/1.6a1) behave rather strangely, if you call abort when the 
readyState is 1, 2, or 3 then as a result of that call the 
onreadystatechange event handler is fired with readyState 4, then 
readyState is changed to 0.

Other implementations (Opera 8.5, IE 6 with Microsoft.XMLHTTP) simply 
abort and set readyState to 0, not firing any onreadystatechange 
handler, certainly not one with readyState 4.

I can't find any open bugs on XMLHttpRequest and abort.

I am not good at reading C++ but the abort implementation at
<http://lxr.mozilla.org/seamonkey/source/extensions/xmlextras/base/src/nsXMLHttpRequest.cpp#671>
indeed seems to do

   ChangeState(XML_HTTP_REQUEST_COMPLETED, PR_TRUE, PR_TRUE);

first and only then does

   ChangeState(XML_HTTP_REQUEST_UNINITIALIZED, PR_FALSE);  // IE seems 
to do it

what other implementations do.

For a client script assigned to onreadystatechange it is obviously 
difficult in Mozilla to distinguish between a normal readyState 4 change 
and one that is caused by an abort call.

Should I file a bug on this?


-- 

	Martin Honnen
	http://JavaScript.FAQTs.com/