authjs-express-demo

This demo show-cases an approach to using Auth.js (formerly NextAuth) in an Express backend.

Development

NB: This demo requires Node 19+ which has support for global crypto and fetch APIs relied on by Auth.js' @auth/core, OR execution with --experimental-global-webcrypto and --experimental-fetch flags.

1. Install dependencies with

   pnpm install

   The project uses pnpm but you can also install dependencies with npm or yarn

2. Run the development server

   pnpm dev

   OR start a server with experimental flags script:

   pnpm build
   pnpm start

How It Works

Auth.js, previously NextAuth, provides a @auth/core package that works across different node frameworks.

However, it is built on top of fetch-API's Request and Response objects.

This means that we have to perform conversion between Express's HTTP based Request and Response objects to the Fetch API equivalents.

The process is as follows:

1. Convert the incoming Express request to the route to a Fetch API Request
2. Pass the request (and authentication config) to Auth() from Auth.js for handling
3. Get the returned Fetch API Response, and convert to an Express response

The conversion logic that makes this demo possible is found in httpApiAdapters.ts.

Acknowledgements

• next-auth-express-demo for Express app setup.
• authjs-node-example for TS configuration and working example.