Express.js Middleware Cheatsheet
Quick reference for built-in, third-party, custom, and error-handling middleware in Express.js.
| Middleware | Description | Example | Category |
|---|---|---|---|
| express.json() | Parse JSON request bodies | app.use(express.json()); | Built-in |
| express.urlencoded() | Parse URL-encoded bodies | app.use(express.urlencoded({ extended: true })); | Built-in |
| express.static() | Serve static files | app.use(express.static("public")); | Built-in |
| cors | Enable Cross-Origin Resource Sharing | import cors from "cors"; app.use(cors()); | Third-Party |
| morgan | HTTP request logger | import morgan from "morgan"; app.use(morgan("dev")); | Third-Party |
| helmet | Secure HTTP headers | import helmet from "helmet"; app.use(helmet()); | Third-Party |
| cookie-parser | Parse cookies | import cookieParser from "cookie-parser"; app.use(cookieParser()); | Third-Party |
| body-parser | Parse request bodies | import bodyParser from "body-parser"; app.use(bodyParser.json()); | Third-Party |
| Custom Logger | Log request info | app.use((req,res,next)=>{console.log(req.method, req.url); next();}); | Custom |
| Auth Middleware | Check authentication | app.use((req,res,next)=>{if(req.user) next(); else res.status(401).send("Unauthorized");}); | Custom |
| Error Handler | Catch errors | app.use((err, req, res, next)=>{console.error(err); res.status(500).send("Server Error");}); | Error Handling |