Can We get last modified data after undo & redo?

GoJS
1

Can We get last modified data after undo and redo?
How to get which data is removed after undo?
How to get which data is added after undo?
Is there any sample for those actions?

2

Define a Model Changed listener:
Model | GoJS API or Diagram | GoJS API

The listener gets called with a ChangedEvent, ChangedEvent | GoJS API. Your case is when (e.change === ChangedEvent.Transaction && (e.propertyName === "FinishedUndo" || e.propertyName === "FinishedRedo")).

At that time e.object may be a Transaction (but it might be null). You can then look at its Transaction | GoJS API to see all of the ChangedEvents that happened in that Transaction.

Also, might this be of any interest to you? Model | GoJS API and State Chart With Incremental Saves