I develop a Javascript Office add-in which can run on Word, Excel and PowerPoint.
One of the features of the add-in is to suggest user to upload current file to our server if the file have changed and/or saved since the last successful upload.
I had some luck with document.properties.lastSaveTime for Word application: https://dev.office.com/reference/add-ins/word/documentproperties?product=word But this API is Word-specific and is not available for other hosts.
Is there a way to get the date of last file change (document, workbook and presentation accordingly to the host application) using shared API, that is, API available for all three hosts?
If such shared API functionality doesn't exist, even some clue of how to get last changed date of individual hosts' files would be helpful.