Microsoft 365 Office 365 Add-ins

Office Add-ins community call–December 9, 2020

November’s call, hosted by David Chesnut, featured the following presenters and topics:

  • Raymond Lu shared updates on the addFromBase64 AP, and some additional Excel APIs.
  • Nisarg Kinariwala showed how to use Office Add-in usage reports to check usage data about your Office Add-in.
  • David Chesnut demonstrated a new PnP sample showing how you can use web workers in custom functions to keep you task pane UI from being blocked.

Watch the call here.


We welcome you to submit questions and topic suggestions in advance of each call by using our short survey form.

AddFromBase64 API updates

  • Are there plans to update the base64 APIs for Word soon?

This update is focused on the Excel API which was in beta. We don’t have any current plans to update this one but if you have issues with it, please log a bug on our office-js Github repo, or create a new feature request on UserVoice (

  • Will the insertFromBase64 API be kept?

If referring to the old API, addFromBase64, then, yes. We don’t have plans to deprecate the addFromBase64 beta API. But we recommend to use the new insertFromBase64 API after it releases to GA.

Miscellaneous questions

  • Are there plans to update the JavaScript API for PowerPoint to broaden access? Example: allow access to interact with the presentation directly.

Yes, we are starting back up on the PowerPoint APIs. We covered this in the September community call where you can find more info: Office Add-ins community call–September 9, 2020 – Microsoft 365 Developer Blog.

  • Any plans for insert slide in PPT?

Yes, this is in preview. See Insert and delete slides in a PowerPoint presentation.

  • Is the open workbook like in Word also available in Excel? context.application.createDocument(mybase64).open();

Yes it’s available in Excel. See Excel.createWorkbook.

  • Do you have any plans to move the shared runtime from IE 11 to EdgeView2?

Yes, as covered in the November call, Sudheer talked about this capability that is rolling out in our November fork. If all goes well, you should be able to try it in the monthly channel in mid-late January. For more info, see Office Add-ins community call–November 11, 2020 – Microsoft 365 Developer Blog.

Unfortunately, we still don’t have a timeline around this issue. It’s still on the backlog, and we’ll post an update to the GitHub issue once we have more information.

  • There are two open entries on UserVoice asking for a solution to sending an email in Outlook compose view using the office.js API. Specifically, to handle Outlook on Window’s cached mode causing delays (of more than 60+ seconds in some cases) when trying to use EWS or REST to send the email. Are there any plans or advised workarounds to help developers improve this scenario for end-users?

Can you provide us links to the UserVoice requests, or more details? Or please post the details to StackOverflow and tag it [office-js][outlook-web-addins]. Thanks!

  • With the deprecation of the Outlook REST API v2.0 (to be decommissioned in November 2022) are there plans to provide a similar seamless usage API option in the add-in API? Seamless as in requires no user interaction e.g. via pop-up, to obtain a usable token client-side as there is today with getCallbackTokenAsync.

We recommend moving from Outlook REST API to Microsoft Graph. A good starting point would be SSO getAccessTokenAsync and use the Graph API.  This recommendation is documented here: [DEPRECATED] Outlook Mail REST API reference (version 2.0) | Microsoft Docs


From December’s call

Office Add-ins community call

Office Add-ins feedback

The next Office Add-ins community call is on Wednesday, December 9, 2020 at 8:00AM PDT. You can download the calendar invite at