Components & Templates Interview Questions

@Input receives data from a parent; @Output emits events to notify parents of changes.

Default strategy checks entire component tree; OnPush optimizes by checking only when inputs change or observables emit.

Use OnPush, trackBy for ngFor, detach change detector where appropriate, and reduce binding complexity.

Use Elements/Inspector for DOM and styles, Network for asset loading, Console for errors, and Performance/Memory panels when Components & Templates affects runtime behavior. Reproduce the issue locally, then isolate whether the root cause is markup, CSS, JavaScript, or network.

Write component or E2E tests, manually test edge cases, and compare against design specs. Check cross-browser behavior and verify that Components & Templates does not regress performance or break existing user flows.

Components & Templates often maps to how you split UI into reusable pieces, pass data, and manage side effects. Clear boundaries around Components & Templates reduce coupling and make components easier to test and refactor as the app grows.

Choose Components & Templates when requirements demand scalability, maintainability, or features the simpler option cannot provide. Be ready to justify the added complexity with concrete project needs such as team size, performance targets, or integration constraints.

Use the official Angular docs for Components & Templates, language or framework references, and reputable community guides. Bookmark release notes and migration guides when upgrading versions, since Components & Templates behavior can change between releases.

Copying snippets without understanding why Components & Templates works leads to fragile code. Beginners often skip error handling, tests, or edge cases. Slow down, trace execution step by step, and validate assumptions with small experiments.

Map Components & Templates to modules/components/services/routes as appropriate. Interviewers want you to explain inputs/outputs, DI boundaries, and how Components & Templates is discovered at bootstrap or via lazy routes.

Inspect component tree, change detection, and injector hierarchy. For Components & Templates, reproduce with a minimal component, enable verbose error stacks, and verify providers are in the correct injector.

Missing unsubscribe, wrong higher-order map operator, or ignoring completion/error paths. Tie the pitfall to a concrete Components & Templates example such as HTTP, forms, or route params.

Strict templates catch nullability and binding mistakes early. For Components & Templates, prefer typed forms/inputs and avoid `any` so the compiler and language service surface errors before runtime.

Move non-trivial transforms out of templates for testability and change-detection cost. Pure pipes help for Components & Templates display logic; impure pipes need justification.

Provide fakes/mocks via TestBed, override providers per test, and keep constructors injectable. For Components & Templates, avoid hard-coded `new` so units stay isolated.

Heavy work in constructors, unbounded subscriptions, or default change detection on chatty components. Explain how you’d spot Components & Templates-related jank with profiling.

Follow team conventions, split concerns into testable units, handle edge cases, and document assumptions. Review similar modules in the codebase, add observability, and ship incrementally with feature flags if Components & Templates is risky.

Watch for bottlenecks, shared state races, config drift, and unbounded resource usage. Load-test Components & Templates paths, set limits, and plan horizontal scaling or caching before traffic spikes.

One approach optimizes simplicity and time-to-market; the other optimizes performance, flexibility, or compliance. Choose based on team skill, traffic, and maintenance horizon—there is rarely a single best answer for Components & Templates.

Reproduce in staging, check logs/metrics/traces, narrow scope with binary search deploys, and write a postmortem. Fix Components & Templates root cause, add regression tests, and improve alerts so similar failures are caught earlier.