The deferred.promise() method is used to return a Promise object to observe when all actions of a certain type bound to the collection, queued or not, have finished.
This method has the form:
deferred.promise([type] [, target])
|type||Specifies the type of queue that needs to be observed|
|target||Specifies the object onto which the promise methods have to be attached|
This form returns a Promise object.