Node.js and Express

What Node.js is (V8 engine, event loop, single-threaded), global objects (process, __dirname, __filename), CommonJS vs ES modules in Node, npm init/install/scripts, package.json and package-lock.json, fs/path/os core modules

Creating an Express app, route methods (get/post/put/delete), route parameters and query strings, request and response objects, sending JSON responses, route organization with express.Router

What middleware is (req/res/next), built-in middleware (json/urlencoded/static), custom middleware (logging/timing/auth), error handling middleware, middleware ordering matters, third-party middleware (cors/helmet/morgan)

Why SQLite for development, better-sqlite3 package, creating tables and schema, CRUD operations (prepare/run/get/all), parameterized queries (SQL injection prevention), transactions, database initialization on startup

Validating request bodies with zod (or joi), schema composition, custom error classes, centralized error handling middleware, async error wrapper, HTTP status codes and when to use each, structured error responses

Authentication vs authorization, password hashing with bcrypt, JWT structure (header.payload.signature), signing and verifying tokens with jsonwebtoken, protecting routes with auth middleware, refresh tokens concept, role-based access control