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Learn about custom functions in Excel.

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Custom functions in Excel

Custom functions enable you to add new functions to Excel by defining those functions in JavaScript as part of an add-in. Users within Excel can access custom functions just as they would any native function in Excel, such as


This repository contains the source code used by the Yo Office generator when you create a new custom functions project. You can also use this repository as a sample to base your own custom functions project from if you choose not to use the generator. For more detailed information about custom functions in Excel, see the Custom functions overview article in the Office Add-ins documentation or see the additional resources section of this repository.

Debugging custom functions

This template supports debugging custom functions from Visual Studio Code. For more information see Custom functions debugging. For general information on debugging task panes and other Office Add-in parts, see Test and debug Office Add-ins.

Questions and comments

We'd love to get your feedback about this sample. You can send your feedback to us in the Issues section of this repository.

Questions about Office Add-ins development in general should be posted to Microsoft Q&A. If your question is about the Office JavaScript APIs, make sure it's tagged with [office-js-dev].

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Additional resources

This project has adopted the Microsoft Open Source Code of Conduct. For more information, see the Code of Conduct FAQ or contact [email protected] with any additional questions or comments.


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