Full Stack developer interview questions

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

Mongo fits flexible documents and fast iteration when schemas evolve.

An index is a sorted structure that helps find documents without a full collection scan.

Sessions store server-side state and send a session id cookie.

I escape output, avoid dangerouslySetInnerHTML, and sanitize any rich text.

It pins exact dependency versions for reproducible installs.

Browsers auto-send cookies, so a malicious site can trigger state-changing requests.

An index on multiple fields matching common filters and sorts.

Backend secrets stay in server env files never committed.

Prefer HttpOnly Secure cookies with rotation, or short-lived access tokens only.

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.

Context or a small store hydrated from /me.

Listen for process warnings, ensure every async path catches, and crash responsibly in production supervisors.

Browsers send OPTIONS before some cross-origin requests.

JSON Schema rules on collections catch bad documents.

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

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

Shared schema packages or OpenAPI-generated types.

Build static assets, health-check new API instances, drain old ones, then point CDN to new files.