Ian,
This is a followup to my previous message.
If onreadystatechange is guaranteed to be called only once for
readyState 3, then I don't see much point in making responseText
available in this state. It seems like it will encourage the use of
window.setTimeout() to poll the responseText property looking for new
stuff...
If you think that programmers might be interested looking at partial
responses, then maybe you should call onreadystatechange each time a new
chunk of the response becomes available.
Furthermore, the ambiguity of the headers is a little problematic. If
you query a header and get null in response, you don't know if it is
because that header was not in the first packet and is yet to come or if
it simply does not exist. I suppose you could check the length of
responseText to determine whether all headers have been downloaded yet
or not. But I'd say that there ought to be some more explicit way to
determine whether all headers have been received. If responseText is
being parsed out and made available on readyState 3, then it seems to me
that you ought to just go ahead and say that state 3 means that all
headers have been received and that the response body is being loaded...
Here's something else to think about: if the server's entire response
arrives in a single packet, can the UA skip state 3 and jump directly to
state 4? Or is there a guarantee that onreadystatechange will be
invoked for each state?
David
