Full Stack developer interview questions

npm install reads package.json and the lockfile, then downloads packages into node_modules including transitive dependencies.

Express is a minimal Node framework for routing, middleware, and HTTP responses.

Middleware is a function with req, res, and next that runs during the request lifecycle.

You attach an HTTP method and path to an app or router, such as app.get('/health', handler).

req is the incoming request: params, query, body, headers, and cookies.

express.json() is middleware that parses JSON bodies into req.body.

Use res.status(code).json(payload) so the client gets the right status and Content-Type.

next() passes control to the next matching middleware or route.

MongoDB is a document database that stores BSON documents instead of rigid rows.

A document is one record, similar to a row but nested and flexible.

Mongoose is an ODM that maps MongoDB collections to Node models.

find returns matching documents as a query result list.

ObjectId is MongoDB's default unique identifier for _id.

CRUD is Create, Read, Update, and Delete.

A schema defines fields, types, required flags, defaults, and indexes for a collection.

React is a library for building user interfaces from components.

JSX is a syntax that looks like HTML inside JavaScript.

Props are inputs passed from a parent and should be treated as read-only.

useState returns the current value and a setter that queues a re-render.

useEffect runs side effects after render, such as fetching data or attaching listeners.