Node.js FAQ: Top Questions

Middleware in Express.js are functions that execute during the request-response cycle, with access to req , res , and next , used for tasks like logging, authentication, or parsing.

• Types: Application-level, router-level, error-handling, built-in, third-party.
• Execution: Runs in order, calls next to proceed.
• Examples: express.json() , custom logging middleware.
• Use Case: Request preprocessing, response modification.