Full Stack Developer 路 Intern to senior
Full stack interviews sample both sides: a question about React state, then one about SQL indexes or API design. Interviewers look for breadth plus a few areas where you go deep.
158 questions
Explain how you assessed urgency, impact, dependencies and risk, then communicated the resulting priorities.
Show respectful disagreement, evidence-based reasoning, willingness to listen and commitment after the final decision.
Identify a recurring source of wasted time or risk, make a focused improvement, and demonstrate its impact.
Explain the manual problem, why automation was worthwhile, how you implemented it safely and what time or error reduction resulted.
Show how you adapted your explanation to the audience, focused on the outcome and avoided unnecessary technical jargon.
Show how you noticed a risk early, validated it, communicated it and added a safeguard.
Describe how you understood the stakeholder鈥檚 goals, handled disagreement professionally and reached a workable outcome.
Validate all input, use parameterised queries, add security headers with helmet, rate-limit requests, restrict CORS, hash passwords, keep secrets in environment variables, and keep dependencies updated and audited.
HashMap is not thread-safe, Hashtable is thread-safe by locking the whole map on every method, and ConcurrentHashMap is thread-safe with much finer-grained locking and lock-free reads, so it scales far better.
The JVM divides memory into a per-thread stack, a shared heap (split into young and old generations) and Metaspace; the garbage collector frees heap objects that are no longer reachable, collecting short-lived young objects frequently and old objects less often.
Explain why you accepted, reduced or paid down technical debt and how you managed the associated risk.
Start with the problem, evaluate alternatives, validate the technology with a small experiment and explain how you managed adoption and risk.
Explain how you identified what the developer needed, coached rather than simply solved the problem, and measured their progress.
Take heap snapshots in Chrome DevTools before and after the suspect action, compare what grew, and fix the retaining reference, which is usually a forgotten listener, timer, global variable or unbounded cache.
A component re-renders when its state changes, its parent re-renders, or a context it consumes changes; you prevent wasted renders by moving state down, using React.memo, and keeping props referentially stable.
Measure first with the Profiler and Lighthouse, then reduce unnecessary renders, split code with lazy loading, virtualise long lists, and optimise images and bundle size.
Core Web Vitals are Google鈥檚 field metrics for real-user experience: LCP (loading), INP (interactivity) and CLS (visual stability). They influence search ranking and are measured on real devices, not only Lighthouse.
Mapped types build a new object type by looping over keys (`{ [K in keyof T]: ... }`). Conditional types pick a result with `T extends U ? X : Y`, which is how many utility types are implemented.
Keep the main thread free by moving CPU-heavy work to worker threads or a job queue, and scale across cores and machines by running multiple processes (cluster or PM2) behind a load balancer with shared, external state.
Isolation levels (Read Uncommitted, Read Committed, Repeatable Read, Serializable) control how much concurrent transactions can see of each other's changes, trading consistency against concurrency to prevent dirty reads, non-repeatable reads and phantom reads.