$.when, $.progress and already resolved deferred

[nicolashenry]

This code :

$.when($.Deferred().notify(1).resolve(), 
$.Deferred().notify(2).resolve(), 
$.Deferred().notify(3).resolve())
.progress(function() {
    console.log(arguments);
});

displays "[1,2,undefined]".
I would expect to have "[1,2,3]" as a result because this behavior with the last notify does not appear to be described in the documentation. If any of the deferred objects is not already resolved, the display is "[1,2,3]".

[dmethvin]

No matter now many (N>1) are combined, the last one never gets a progress notification. http://jsbin.com/muhuxireko/1/edit?js,console

For reference, the docs say:

When the Deferred is resolved or rejected, progress callbacks will no longer be called, with the exception that any progressCallbacks added after the Deferred enters the resolved or rejected state are executed immediately when they are added, using the arguments that were passed to the .notify() or notifyWith() call. http://api.jquery.com/deferred.progress/

When deferred.notify is called, any progressCallbacks added by deferred.then or deferred.progress are called. Callbacks are executed in the order they were added. Each callback is passed the args from the .notify(). Any calls to .notify() after a Deferred is resolved or rejected (or any progressCallbacks added after that) are ignored. http://api.jquery.com/deferred.notify/

Frankly I wouldn't have even expected the combined Deferred to report progress from the individual ones. These kind of situations are probably some of many reasons why standard Promise punted on progress. Others, thoughts?

[dmethvin]

@jaubourg any input?

[jaubourg]

I cannot properly investigate since I'm travelling until monday. I'll look into it then.

[nicolashenry]

I think the problem comes from here (deferred.js#L134) :

resolveValues[ i ].promise()
    .done( updateFunc( i, resolveContexts, resolveValues ) )
    .fail( deferred.reject )
    .progress( updateFunc( i, progressContexts, progressValues ) );

The progress update should perhaps be done first :

resolveValues[ i ].promise()
    .progress( updateFunc( i, progressContexts, progressValues ) )
    .done( updateFunc( i, resolveContexts, resolveValues ) )
    .fail( deferred.reject );

[jaubourg]

I think that's the problem too. Wanna make a PR for this with a nice unit test to boot @nicolashenry? :)

[nicolashenry]

Is it okay that way?

[markelog]

Merged! Thank you