Sometimes when more than one workbook is opened, then a:
GeneralException: There was an internal error while processing the request
is thrown during various office-js operations.

See https://github.com/OfficeDev/office-js/issues/771 for details.

I know there's a workaround:
https://docs.microsoft.com/en-us/office/troubleshoot/excel/force-excel-to-open-new-instance
but it's impossible to force clients to use it.

I am attempting to use the Document.getFileAsync method in Office Excel 2016 on Windows. Executing the method fails with an "Permission Denied" error.

Error code: 7000
Error name: "Permission Denied"
Error message: "You don't have sufficient permissions for this action."

This functionality is critical to our Add-in and we have many customers that use this 2016 volume licensed version of Office. They are not able to upgrade since the version is locked down at 16.0.4266.1001.

In Office Excel, you have an option to implement an arrow style in your line chart for a data series.

However, it seems like the office.js library is unable to implement this option.

Excel.Line has the option I'm looking for (beginArrowheadLength, beginArrowheadStyle, etc, ), but it was strictly for shapes, completely separate from series charts, and has no way to somehow implement a custom shape to the data series.

Adding this feature would help me greatly to create a chart directly to excel instead of building a custom chart inside the page.

More information on my stackoverflow question:
https://stackoverflow.com/questions/59971581/microsoft-office-js-excel-add-in-how-to-implement-arrow-style-for-a-data-serie

Is it possible to get Excel comment cell reference directly using Office.js?
Right now there is no reference regarding the cell the comment is written into.

Is it possible to set the author and the creation date of an Excel comment as writable using Office.js?

While the new stocks data type is fine, those of us NOT wanting Stocks are faced with a new persistent pop up tag suggesting we "convert" anything that kind of looks like a ticker symbol. This tag maddeningly blocks adjoining values that we NEED TO SEE while working.

While applying the Consolidation option in excel, it shows as "Book 1" for all the consolidated sheets instead of a respective worksheet name.

Currently office.js does not provide an API for accessing Automatically Expend Table Option or other auto correct options for tables.
In VBscript you would use Application.AutoCorrect object. Having something like that would be very useful.

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User can't customise date format of the data that has been rendered by custom-function - dynamic array formula.

for more info: https://github.com/OfficeDev/office-js/issues/1068

Please add a feature to render html inside a shape similar to that of addTextBox can we get a addHtml feature so that we can save html styled content along with the document

In current version of Office JS, we are not able to disable resizing and moving of dynamically created Slicer.
This would be useful if we want to restrict user from moving the slicers.
Equivalent to VBA property , Slicer.DisableMoveResizeUI

Excel Add-In

Spreadsheets built for handling financial data need access to the corporate database. Presumably that is why capabilities are provided within Excel to define and execute SQL queries within the context of a workbook/worksheet.The role of an Add-in to provide a whole host of capabilities to the workbook author cannot be overstated. Yet OfficeJS Excel API seem to be lacking the ability to define, access, and execute the aforementioned queries. Are there any plans in the works to provide the capabilities?
The lack of this capability particularly affects 3rd party add-in providers who cannot otherwise access a customer's corporate database.

I am using Office.js API and javascript/react.js for an Excel Add-in and wants to perform an action (execute a function) when the active worksheet/workbook is saved by user.

When working on Excel Add-In, specifically with Data Validation lists, is it possible to retrieve the source of the list?

Most collection objects in the JavaScript API have a .getItemAt method. This allows you to access user-created objects without having to know how they're named. PivotTableCollection lacks this method.

EmbeddedSession (https://docs.microsoft.com/en-us/javascript/api/office/officeextension.embeddedsession?view=common-js) is only supported for Visio (https://docs.microsoft.com/en-us/office/dev/add-ins/reference/overview/visio-javascript-reference-overview). We would like to be able to embed an Excel workbook on a public web page and be able to control it via Office.js.

You can embed Excel via the OneDrive embed > JavaScript configurator and control it using the very old JavaScript API (https://docs.microsoft.com/en-us/previous-versions/office/developer/sharepoint-2010/hh315812(v=office.14)), but that API lacks many key features of Office.js.