Master middleware, routing, error handling, and RESTful API design with Express
Start Practicing NowUnderstand middleware chain, custom middleware, and best practices
Design RESTful endpoints, handle validation, and structure responses
Learn authentication, authorization, CORS, and security best practices
Select Express.js as your interview topic and customize the difficulty level
Answer realistic Express.js interview questions in a simulated environment
Receive detailed feedback on your answers, including areas to improve
Monitor your improvement and identify strengths and weaknesses
Middleware and request/response cycle
Routing and route parameters
Error handling middleware
RESTful API design patterns
Authentication and authorization
Security best practices (helmet, CORS)
A: Middleware functions have access to request, response, and next. They execute sequentially in the order defined. Each middleware can modify req/res, end the request, or call next() to pass control. Types: application-level (app.use), router-level, error-handling (4 parameters), built-in, third-party. Order matters!
A: Use error-handling middleware with 4 parameters: (err, req, res, next). Place it after all other middleware/routes. For async errors, pass to next(err) or use try-catch with async/await. Libraries like express-async-errors handle async errors automatically. Always have a catch-all error handler.
A: Request enters Express, passes through middleware stack in order. Each middleware can: process and pass to next(), send response (ends cycle), or throw/pass error to error handlers. Route handlers are specialized middleware. Response methods like res.send(), res.json() end the cycle.
A: Common approaches: Session-based (express-session + passport), Token-based (JWT), OAuth. For JWT: verify token in middleware, attach user to req.user, protect routes. Use bcrypt for password hashing. Implement middleware to check authentication: if (!req.user) return res.status(401). Consider libraries like passport.js.
Understand middleware execution order and when to use app.use vs app.get
Practice implementing authentication with JWT and session-based approaches
Know how to structure larger Express apps with routers and controllers
Master error handling patterns for both sync and async route handlers
Understand security best practices: helmet, CORS, rate limiting, input validation
Join thousands of developers who have improved their interview skills with Vibe Interviews
Start Your Express.js Interview Practice