In jQuery 1.8, the .then() method creates a new promise rather than adding a callback to the existing promise. This provides better interoperability with other Promise/A implementations. To get the old behavior, use deferred.done(done1).done(done2);

Although this was mentioned in the blog notes the docs do need to be updated.

Whether or not it creates a new promise object, this behavior is still incorrect. The callbacks that are attached should be called with the arguments of resolve(), regardless of which promise object they were attached to. This is a bug.

The same incorrect behavior is produced by the promise object returned by Deferred.then().

Deferred.promise() returns a promise object that exhibits correct behavior.

This code snippet also shows the behavior in the console:

var x = new $.Deferred();

x.then(function(res){console.log(res);}).then(function(res){console.log(res);});

x.resolve([1,2]);

[1,2] should be logged to the console twice, but instead it is logged once and then undefined is logged.

Does this clarify things for you? http://jsfiddle.net/4TVLq/

Because we get so many tickets, we often need to return them to the initial reporter for more information. If that person does not reply within 14 days, the ticket will automatically be closed, and that has happened in this case. If you still are interested in pursuing this issue, feel free to add a comment with the requested information and we will be happy to reopen the ticket if it is still valid. Thanks!