At the moment Word runs Add-ins in IE11

IE11 doesnt support ES2016, and is therefore much harder to develop for than all of the other newer browsers (Safari, Chrome, Edge).

Word should run Add-ins in Edge

This is needed so that we don't have to call saveAsync every time to get itemid (this will trigger Attendee notification dialogs)

Office 365 shared mailboxes are very useful. Unfortunately, they do not load outlook web add-ins right now: see http://stackoverflow.com/questions/35059067/make-outlook-add-ins-working-with-office-365-shared-mailboxes/35065215
This would be terrific to have add-ins for such mailboxes especially for all CRMs related apps

Currently, the requiredAttendees methods setAsync and getAsync have serious issues when resources of room type are used. I will add below my review of the three methods exposed on requiredAttendees object (picture in the link):

http://s17.postimg.org/satnvyrz3/RequiredAttendeesCalls_Behavior.png

Currently OfficeJS only supports simple string type for the meeting Location property, and I would like to be able to access the same complex object type as is exposed in the O365 APIs.

Note that Outlook users can input a resolved address in the meeting form for Location, and O365 APIs already support this complex type for Location (https://msdn.microsoft.com/en-us/office/office365/api/complex-types-for-mail-contacts-calendar#Locationv10)

Vote to update the OfficeJS to support this same Location object.

Would like to have an ItemSend event in the web API just like the regular API does. Is that on the planning stage for future releases?

Similar to Document.SelectionChanged event, the following Workbook-level events would be useful to have exposed via the JavaScript API (in no particular order):

Activate,Deactivate
BeforeSave,AfterSave
BeforeClose
Shutdown
SheetActivate,SheetDeactivate
SheetBeforeDoubleClick
SheetBeforeRightClick
SheetChange
SheetSelectionChange

As referred to the post:
https://social.msdn.microsoft.com/Forums/office/en-US/720a1bd6-abb9-4f75-863f-1fc33256a629/is-there-an-event-for-when-recipients-change-in-outlook-2013?forum=appsforoffice

there is no event JavaScript API an add-in for Outlook could use to react to a change in email message being written (compose mode).
For example if the user adds further To, Cc or Bcc Addresses, it would be advantageous if the add-in could react to it and display relevant data.

Add User Defined function support to the Apps for Office Excel APIs so that users can enter formulas in excel. User Defined Functions are one of the most powerful features of Excel (and some competitor spreadsheets products now available in the web). They are critical for us to make our Apps for Office product as powerful as our legacy on premise product.

We can read/update custom properties in Word. It would be great if we can have similar function in Excel also.

We are also concerned about the issue mentioned on this post:

http://stackoverflow.com/questions/38847193/excel-office-add-in-api-worksheet-protection-password

Currently we are able to protect and unprotect a worksheet. What we need is an API for password protection of worksheets which the end user would not know as this is will make the worksheets on OneDrive more secure for use.

We need host information for tracking environments and reproducing errors.
The method with requirements checking and the undocumented feature with reading the sessionStorage or querystring are painful as requirements change and undocumented features disappear.

Office.js could provide an API for this, as its internally use host information to load custom host scripts.

There should be a way to open a external excel workbook by providing URL for that file on excel online via officejs. so that user can open a template stored on some other server which contains desired formatting and named-ranges which can be modified on Excel Online

The ability to edit conditional formatting in OfficeJS Excel API.

We have a need to repeat the same formatted Worksheet over and over based on selections made by the user. It would be great to setup a template so that same worksheet can be copied. The worksheet has all formatting including printing stuff in place already. Be great to just be able to copy that and fill in the data.

Since there is no way to cancel the changes made by an add-in, we need to provide users with backup options.

The current version of JavaScript API for Excel doesn't have a method for copying a sheet with its data and formatting, there are no elegant and fast workarounds available.

Could you please let us know if it's possible to add this method to JavaScript API for Excel?

Enhance the Office JavaScript APIs (for Excel 2016+) to expose a mechanism (perhaps a Validation relationship or property) that allows the developer to configure a cell so that the end-user selects the value for the cell by picking from a list of values. The list of values might be specified by some other range. In a VSTO add-in (and native Excel) this can be achieved by configuring the Data Validation properties on a cell/range.

It will be good to have access to CustomXmlParts for Excel via JS APIs. Currently it supported only by Word. It allows developers to provide coolest plug-ins for Excel 365.