$.ajax method question/bug

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Hi,<o:p></o:p>
<o:p> </o:p>
I’ve come across an issue in jQuery 1.3.2 that was not
in 1.2.6 that I think may be a bug. If it’s not a bug, I was
just wondering under what conditions that is required? The only thing
that I could find in your tickets that is similar is ticket #5114.<o:p></o:p>
<o:p> </o:p>
My issue is that I store an Ajax HTTP
Request object for use by javascript in a future user interaction after the
success method is executed for an <st1:place w:st="on"><st1:City w:st="on">Ajax</st1:City></st1:place>
call. When jQuery 1.3.2 was introduced, this functionality stopped
working. The root of the problem, I think, is that the jQuery
1.3.2 command “.ajax” OnReadyStateChange function has
introduced a conditional block that if set calls an abort on the HTTP Request
object which erases the XML Response. The jQuery “<st1:place w:st="on"><st1:City w:st="on">ajax</st1:City></st1:place>”
function sets up an OnReady State Change function in the variable
“onreadystatechange” with one parameter “isTimeout”,
which from the code can be interpreted as a flag indicating that the callback
was triggered by a timeout function if the argument is a string with the value
of “timeout”. In jQuery 1.3.2, this onreadystatechange
function was augmented to detect if a timeout had occurred and call the “abort”
method in the HTTP Request object. It does this by checking if the
variable “isTimeout” is set or not and not against the
“timeout” string. Since my <st1:City w:st="on">Ajax</st1:City>
calls are asynchronous calls, jQuery does not register the onreadystate
function with javascript’s <st1:place w:st="on"><st1:City w:st="on">ajax</st1:City></st1:place>
on ready change callback registration. Instead it uses
“setInterval” to poll the current state of the <st1:place w:st="on"><st1:City
w:st="on">ajax</st1:City></st1:place> call by registering the
onreadystatechange function just created as the callback to
setInterval. I can’t find any reference to a callback of
setInterval setting any arguments, thus when setInterval fires and calls
onreadystatechange function, the value of isTimeout is some interger value that
I don’t know what it is referring too? Since the abort
condition blindly checks if “isTimeout” is set, which it is, the
abort is called and my object’s variable which stores a reference to that
HTTP request object has it’s objects state changed and the data retrieved
from a valid successful request erased. Since this abort is
called after the success function is run, the <st1:place w:st="on"><st1:City
w:st="on">ajax</st1:City></st1:place> response data is consumed correctly and
that instance of display is correct. Subsequent use of that data is
no longer valid.<o:p></o:p>
<o:p> </o:p>
I believe the correct code should be <o:p></o:p>

if ( isTimeout == “timeout” )<o:p></o:p>

xhr.abort();<o:p></o:p>
<o:p> </o:p>
because the
“onreadystatechange” argument comes from either the setInterval, or
one of the calls below. In the asynchronous state, if the timeout
is set and the setTimeout setting expires, the function is called with the
string “timeout” and in the synchronous state, the function is
called with a NULL value.<o:p></o:p>
<o:p> </o:p>
3397: <st1:place
w:st="on"><st1:City w:st="on">ajax</st1:City></st1:place>: function( s ) {<o:p></o:p>
<o:p> </o:p>
…<o:p></o:p>
<o:p> </o:p>

// Wait for a response to come back<o:p></o:p>

var onreadystatechange = function(isTimeout){<o:p></o:p>

// The request was aborted, clear the interval and decrement jQuery.active<o:p></o:p>

if (xhr.readyState == 0) {<o:p></o:p>
<o:p> </o:p>
…<o:p></o:p>
<o:p> </o:p>

// The transfer is complete and the data is available, or the request timed out<o:p></o:p>

} else if ( !requestDone && xhr && (xhr.readyState == 4 || isTimeout == "timeout")
) {<o:p></o:p>

requestDone = true;<o:p></o:p>
<o:p> </o:p>

// clear poll interval<o:p></o:p>

if (ival) {<o:p></o:p>

clearInterval(ival);<o:p></o:p>

ival = null;<o:p></o:p>

}<o:p></o:p>
<o:p> </o:p>

 status
= isTimeout == "timeout" ? "timeout" :<o:p></o:p>

!jQuery.httpSuccess( xhr ) ? "error" :<o:p></o:p>

s.ifModified && jQuery.httpNotModified( xhr, s.url ) ?
"notmodified" :<o:p></o:p>

"success";<o:p></o:p>
<o:p> </o:p>
…<o:p></o:p>
<o:p> </o:p>

// Fire the complete handlers<o:p></o:p>

complete();<o:p></o:p>
<o:p> </o:p>
 3609:
 if
( isTimeout )<o:p></o:p>

xhr.abort();<o:p></o:p>
<o:p> </o:p>

// Stop memory leaks<o:p></o:p>

if ( s.async )<o:p></o:p>

xhr = null;<o:p></o:p>

}<o:p></o:p>

};<o:p></o:p>
<o:p> </o:p>

if ( s.async ) {<o:p></o:p>

// don't attach the handler to the request, just poll it instead<o:p></o:p>
 3620:
 var
ival = setInterval(onreadystatechange, 13);<o:p></o:p>
<o:p> </o:p>

// Timeout checker<o:p></o:p>

if ( s.timeout > 0 )<o:p></o:p>

setTimeout(function(){<o:p></o:p>

 //
Check to see if the request is still happening<o:p></o:p>

if ( xhr && !requestDone )<o:p></o:p>

onreadystatechange( "timeout" );<o:p></o:p>

}, s.timeout);<o:p></o:p>

}<o:p></o:p>
<o:p> </o:p>
<o:p> </o:p>
…<o:p></o:p>
<o:p> </o:p>

// firefox 1.5 doesn't fire statechange for sync requests<o:p></o:p>

if ( !s.async )<o:p></o:p>

onreadystatechange();<o:p></o:p>
<o:p> </o:p>
<o:p> </o:p>
Thomas Poslinski<o:p></o:p>
Synacor Inc.<o:p></o:p>
<o:p> </o:p>
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Topic Participants
tposlinski

$.ajax method question/bug

$.ajax method question/bug

Topic Participants

tposlinski