How about a changed?

[deitch]

This is very cool, a nice addition to backbone that should probably be rolled into the core. How about a "changed" list?

Core backbone has isChanged() and changedAttributes which give if there have been any changes since the last "change" event, and those attributes that have been changed since. Having similar ones that can give if there is a differential between the last store() and current state, and those changes, would be useful.