Senior
39 bites tagged Senior — interview questions with model answers, and 60-second explainers.
What is a build artifact? Give Java, JS, and C++ examples.
Define artifacts as compiled outputs; list JAR/WAR for Java, webpack bundle for JS, and binary/.so for C++; note immutability. Your grasp of the source-to-deployable boundary in CI/CD.
What strategy would you propose to fix an unmanageable backlog?
Expose bloat, inspect for value so the PO re-orders and trims waste, then inspect regularly. Do you see bloat as a transparency and ordering problem for the PO? Never let the team delete without the PO or treat the backlog as unordered.
How would you diagnose and optimize slow Angular component tests?
Tests Angular test economics and runner overhead. Strong answers profile with Vitest, swap Karma for jsdom/happy-dom, mock services, and reduce TestBed recompilation via targeted imports.
How do Vue and Angular detect nested object mutations?
Tests deep reactivity vs reference-based detection. Vue 3 Proxies catch nested mutations; Angular Default checks on zone ticks and OnPush misses same-reference changes. Fix via immutability, deep watchers, or ngDoCheck.
Outline a research plan to diagnose low adoption despite positive usability tests
Tests distinguishing usability from adoption drivers. Strong answers hypothesize discoverability, motivation, and timing gaps; use behavioral triangulation, contextual inquiry, and surveys. Red flag: blaming users or redesigning before diagnosing the funnel.
How would you mitigate latency in a low-bandwidth remote usability study?
Tests planning for 2-5Mbps rural 3G research constraints. Strong answers cover: lightweight prototypes with compressed assets; 3G-throttled environments plus backup comms; data-cost compensation. Red flag: heavy screen-share tools without offline fallbacks.
What research validates a three-sprint feature without delaying engineering?
One week of interviews and prototype tests, with concept testing while engineering spikes. Parallel Lean UX sprints de-risking large builds without blocking engineers.
How do you adapt contextual inquiry for internal API and tool design?
This tests applying ethnographic methods to API design by observing engineers at work, surfacing invisible habits, and mapping findings to endpoint granularity and docs. A red flag is treating internal users as unlike external customers or using only surveys.
Apply differential privacy to user behavior queries and explain epsilon trade-offs
Mastery of formal privacy guarantees and noise-based query systems. Inject Laplace or Gaussian noise scaled to query sensitivity; track cumulative epsilon across queries; lower epsilon tightens privacy but increases variance and error bars.
How do you write a declaration file for a JavaScript class?
Declare a class in a .d.ts, type the constructor, add instance members, and attach statics on the class. Ambient class declarations that model instance and static members of untyped JS.
Explain TypeScript Project References in a monorepo and their configuration
This tests monorepo build scaling. Good answers: split into composite projects with references arrays, use tsc --build for incremental compilation, and consume .d.ts outputs for boundaries. Red flag: calling it path mapping or omitting --build.
How do you type a function with string and number overloads?
Tests if you know overloads are public API and the implementation uses a union. Answer: write process(string):string and process(number):number overloads, then implement with string|number and narrow. Red flag: exposing only the implementation signature.
Build a typesafe ApiRoute type using template literal types
Tests type-level string composition with template literals. Good answer: define a Resource union, interpolate it into /api/v1/ paths, then union with the /{id} variant. Red flag: suggesting runtime regex or plain string instead of literal types.
What is a type predicate? Write a custom type guard for User.
Tests if you know a type predicate is a compile-time narrowing hint requiring runtime validation. Great answers define parameter is Type, validate every User property, and demonstrate narrowing. Red flag: omitting runtime checks or using as casting.
Key differences: type alias vs interface for object shapes
Tests your grasp of TypeScript extensibility and declaration merging. Contrast interfaces' extends and open merging against type aliases' unions, intersections, and primitives; prefer interfaces for public APIs and types for unions or mapped types.
CSS Custom Properties vs JS Theme Object in React
Tests render overhead vs CSS cascade. Strong answers: CSS variables update styles without re-renders, while JS theme objects in Context force subtree re-renders. Mention scoping, SSR FOUC, and setProperty interop.
Why is exhaustive-deps critical and when can you disable it?
This tests closure and effect timing intuition. A strong answer explains missing deps let effects read stale render values, gives a concrete override like a ref or stable callback, and warns that silencing the rule hides refactor hazards.
Write the React.createElement() equivalent for this JSX
Tests JSX-to-JS compilation mechanics. Answer: createElement('a', {href: '/home', className: 'link'}, 'Go Home'). Children must be the third argument, not inside props. Red flag: nesting children in props or using an unquoted tag variable.
Explain prop drilling and why it's a problem
Tests coupling in deep React trees. Good answers define prop drilling as forwarding props through unused intermediaries, cite coupling and refactor pain, and name Context or composition as fixes. Red flag: calling props bad or jumping to Redux without Context.
Add a custom x- field to a FastAPI path operation schema
Tests knowledge of FastAPI's built-in OpenAPI extension hook. Answer: cite the path operation decorator's extra-schema dict (OpenAPI Extra) to merge x-internal-id directly. Red flag: proposing manual JSON editing or schema post-processing.
How do you manage service lifecycle with FastAPI Depends versus formal DI?
Tests scaling FastAPI DI beyond routes. Answer: use Depends(yield) for request-scoped DB sessions; use a formal container for deep singleton service graphs and lifespan wiring; hybrid is best. Red flag: using Depends for everything and ignoring testability.
Explain the internal role of the Depends class
A strong answer notes it marks parameters for solver, enables recursive sub-dependencies and Annotated sharing, and feeds OpenAPI. If you treat Depends as FastAPI's core DI declaration primitive.
Your feature launches but engagement doesn't move. What's engineering's role in diagnosis?
Validate data, segment users, test tech and behavioral hypotheses, propose experiments. If engineering owns metric diagnosis or deflects to product. Blaming users without checking instrumentation first.
Describe leading vs lagging indicators with technical performance examples.
Tests your ability to distinguish predictors from outcomes. A strong answer defines causality, offers a leading metric like cache hit rate, and a lagging metric like P99 latency. Red flag: offering only business metrics or confusing activity with outcomes.
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