How to implement an 'undo' functionality for an Office Add-In using the JavaScript API

Question

How to implement an 'undo' functionality for an Office Add-In using the JavaScript API?

Right now all changes made by an Add-In are non-reversible by the user and it appears that Microsoft is not working on an easy way to enable the Add-In changes being 'undoable'. Even though developers have been requesting this feature:

• https://officespdev.uservoice.com/forums/224641-general/suggestions/10754793-add-a-method-to-copy-a-sheet-with-all-data-and-for
• https://officespdev.uservoice.com/forums/224641-general/suggestions/6273172-allow-edits-made-by-office-js-api-functions-setda

Answer 1

Thanks for bringing this up.

The fact that the undo stack gets cleared when you execute the APIs is -- for Excel -- unfortunately unavoidable. You get the same behavior in VBA or VSTO, and it has to do with the way that Excel is fundamentally designed. Perhaps we could be a tad better at remembering undos for trivial operations, but even the UI itself or Excel Online will clear away the undo stack for things like deleting a sheet.

That being said, I do appreciate both suggestions, and have already passed them along to the team. Namely:

• Avoid clearing the undo stack on read-only operations; only clear it on 'write'.
• Think about some sort of copying/serialization method for worksheets, so that there's a state to revert to.

We'll see what we can do.

Answer 2

Note that this is something specific to Excel (which i see from your uservoice request), but should not be generalized to the other Office Applications. For instance, in Word the end user driven undos after API calls is supported.