What is azure-functions-nodejs-library?

Azure Functions Node.js Library is the official package that lets you write serverless functions in JavaScript or TypeScript and run them on Microsoft's cloud. Instead of managing a full web server that's always running, you write small pieces of code that only execute when something triggers them, like an incoming HTTP request or a new file being uploaded. You install it with a standard npm command, then write a function that receives a request and returns a response. The README shows a straightforward example: a function that reads a "name" parameter from a URL query string or request body, and responds with "Hello, [name]." You register each function with the framework by calling methods like app.http(), specifying which HTTP methods to accept and the handler function to run. The library handles the plumbing of connecting your code to Azure's infrastructure. This is for developers building backend services on Azure who want to avoid the overhead of maintaining a persistent server. Practical use cases include processing webhooks, handling form submissions, running scheduled cleanup tasks, or building API endpoints for a mobile app. It supports both JavaScript and TypeScript, and works with Node.js versions 22 and 24. One thing the README highlights is an important distinction: the "programming model" (this library, which defines how you write your code) is separate from the Azure Functions "runtime" (the underlying engine that runs everything, shared across all languages). Both happen to be on version 4 right now, but they update independently. The README also warns that you can't mix version 3 and version 4 of the programming model in the same app, so teams upgrading need to migrate all their functions at once.