Full Stack developer interview questions

HTTPS encrypts traffic so attackers on the network cannot read tokens or form data.

A WebSocket is a persistent two-way connection after an HTTP upgrade.

Use WebSockets when the client must receive updates immediately without polling.

Caching stores expensive results so the next request is faster.

Browser caching uses HTTP headers such as Cache-Control to reuse static assets.

Continuous Integration automatically builds and tests every change.

PR checks catch broken builds before they reach main.

nginx is a reverse proxy and static file server.

A .env file holds local configuration such as PORT, MONGO_URI, and JWT_SECRET.

NODE_ENV tells libraries whether the process is development, test, or production.

Node handles many concurrent I/O waits on one thread with a non-blocking event loop.

It pins exact dependency versions for reproducible installs.

REST styles APIs around resources and HTTP verbs: GET read, POST create, PUT or PATCH update, DELETE remove.

It parses JSON bodies into req.body.

Browsers send OPTIONS before some cross-origin requests.

I either update local state from the response or refetch the list.

Tests green, no secrets, clear description, and screenshots for UI.

Cross-origin requests with custom headers or methods trigger a CORS preflight.