Office js Excel Add-In Sharing state across workbooks

Question

I have recently moved from developing VBA Excel Add-Ins to using the new Office JavaScript Add-ins platform. I am used to my VBA Add-In being active across the whole of Excel and the state of the variables is available no matter what workbook you are interacting with.

This does not seem to be the case with JavaScript Add-ins. I have been testing my Add-In and happened to create a new workbook and noticed that none of the Add-In state appeared to be active any longer.

Am I missing something or is this a consequence of the new Office JavaScript Add-ins architecture where it runs inside a browser within Excel?

Just to confirm I have already enabled the Shared Runtime option, that is not my question. I am able to share state between Commands, Takspane and Functions. But all within a single workbook.

I have tried one of the example Yeoman generator for Office Add-ins and it certainly seems that global variables are not shared between the Add-In in two different workbooks.

Answer 1

This behavior is expected. With Office (web) add-ins, each add-in runs in an embedded JavaScript runtime that is a completely separate process from Office and any other add-ins, so it cannot share data across add-ins. Some people have made sharing across add-ins work using the OfficeRuntime.storage object, but it only works in Windows. It won't work on Mac or in Office on the web. Frankly, the Office platform team considers it a bug that it can be done on Windows and that may be fixed at any time, so you should not create an add-in that depends on it even if you know your add-in will only be run on Windows.

Depending on what your scenario is, you might be able to store state in the document with either Office.document.settings or Office.document.customXmlParts. Another possibility is to store state in a database on your server side.