What is Node.js?

Node.js is an open-source runtime environment that enables programmers to run JavaScript code on the server side. It is built on Chrome's V8 JavaScript engine and allows the creation of scalable web servers and applications. Node.js is characterized by an event-driven, non-blocking I/O mechanism, which makes it suitable for real-time and command-line applications, REST API servers, and network programs. Being cross-platform, it allows applications to run on various operating systems such as OS X, Windows, and Linux.

Introduced by Ryan Dahl in 2009, Node.js is a server-side platform that extends JavaScript's capabilities beyond the browser. It provides a rich library of JavaScript modules, simplifying the development of web applications. Node.js is also used for server-side scripting, allowing the creation of APIs, console-based applications, and web-based applications without the need for threading or networking complexities.

As a web technology, Node.js supports various data types and structures similar to those in JavaScript, including buffers for binary data and strings that can be manipulated using built-in functions. It adheres to JavaScript syntax for defining functions and objects, making it familiar and accessible to JavaScript developers. The Node.js platform is released under the MIT license, ensuring that it is free to use and distribute.

Node Plugins for Excel

Creating Office Add-ins

Node.js is an essential tool for developing Excel add-ins as it is required to create an Office Add-in. The development process is streamlined by the Yeoman generator for Office Add-ins, which scaffolds a Node.js project. This project can then be managed using Visual Studio Code, offering a comfortable development environment for programmers.

Integrating with Visual Studio

For those who prefer a more integrated development environment, Visual Studio can be used to create a Visual Studio solution for Excel add-ins. It is important to note that both Node.js and the Yeoman generator for Office Add-ins are prerequisites for developing Excel add-ins, which also require an Office 365 subscription to function properly.

Common Use Cases

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  Use case 1: A user wants to import a list of file and folder names from their OneDrive for Business into an Excel spreadsheet to manage project documents.
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  Use case 2: A user wishes to access and display their profile information from Microsoft Graph in an Excel task pane for reporting purposes.
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  Use case 3: A user needs to refresh their SSO token seamlessly within Excel when the existing token has expired, to continue using the add-in without interruption.
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  Use case 4: A developer wants to test a new feature of the add-in by sideloading the updated version into Excel to verify its functionality before deployment.
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  Use case 5: A user encounters an error while the add-in is calling Microsoft Graph services, and the add-in needs to display a meaningful message and offer the option to retry the operation.

Frequently Asked Questions

How does the node plugin for Excel handle user authentication?

The node plugin for Excel enables single sign-on for Office Add-ins, allowing an Office Web Add-in to use the sign-in status of Office to authorize users to the add-in and to Microsoft Graph without a second sign-in. It uses Office SSO or MSAL for authentication and can handle authentication errors and token expiration issues.

What does the middle-tier server in the node plugin for Excel do?

The middle-tier server built with Node.js and Express exposes a REST API, /getuserfilenames, which returns a list of file names from the user's OneDrive. It uses the token obtained via OBO to call Microsoft Graph services and return the results to the task pane.

Can the node plugin for Excel be extended to access other Microsoft Graph data?

Yes, the add-in can be extended to access any Microsoft Graph data. The task pane calls a middle-tier REST API when it needs Microsoft Graph services, and the middle-tier uses the token obtained via OBO to call Microsoft Graph services.

What are the requirements for installing the node plugin for Excel?

The plugin requires Node.js, Git Bash, a code editor like Visual Studio Code, and files stored on OneDrive for Business. It is compatible with certain builds of Microsoft 365 that support the IdentityAPI 1.3 requirement set.

How does the node plugin for Excel handle token expiration and errors?

The plugin has error handling capabilities for various scenarios including Microsoft Graph API errors and expired tokens. It utilizes the On-Behalf-Of flow (OBO) to work with tokens and includes error handling for expired tokens during the OBO flow.