Full-Stack Development Case Studies & Practical Application 3

Question 1

A SaaS dashboard loads a 50,000-row data table in the browser, causing the UI to freeze on render. What is the most effective solution?

Accepted Answer

Implement server-side pagination and only fetch the current page of rows

Answer

Server-side pagination sends only the visible subset of data, drastically reducing DOM nodes and render time.

Question 2

A REST API endpoint is being called 10,000 times per second by a single client bot, causing service degradation for real users. What is the correct infrastructure-level response?

Accepted Answer

Implement rate limiting per IP or API key at the gateway layer

Answer

Rate limiting at the gateway rejects excess requests before they reach the application, protecting backend resources.

Question 3

A mobile app sends user passwords in the request body over HTTPS. A developer suggests hashing passwords client-side before sending. Why is this NOT a security improvement?

Accepted Answer

HTTPS already encrypts the body, so the hash becomes the effective password and adds no protection

Answer

If the hash is transmitted as the credential, an attacker who captures the hash can replay it — the hash just becomes a new plaintext password.

Question 4

A team's CI pipeline takes 45 minutes, slowing delivery. Tests are split into unit, integration, and end-to-end suites. What reorganization cuts pipeline time most effectively?

Accepted Answer

Run unit tests first; fail fast, then run integration and E2E in parallel only if unit tests pass

Answer

Fast unit tests act as a cheap gatekeeper; expensive E2E tests run in parallel only when the cheap gate passes, minimizing wasted CI minutes.

Question 5

A Node.js API server crashes every few hours with 'heap out of memory' errors under normal load. What is the most likely cause and first diagnostic step?

Accepted Answer

There is likely a memory leak; use a heap profiler like Node's --inspect flag to record allocations over time

Answer

Periodic OOM crashes under normal load are the classic symptom of a memory leak; heap profiling reveals which objects are accumulating.

Full-Stack Development Practice Test

Full-Stack Development Practice Test

Full-Stack Development Case Studies & Practical Application 3