Angular Developer Technical Questions Interview Questions
10 curated questions with evaluation guidance for hiring managers.
Explain Angular's change detection strategy. How does OnPush work differently from Default?
Should explain zone.js triggering change detection, Default checks all components, OnPush checks only when inputs change, events fire, or async pipe emits. Look for performance optimization knowledge.
How do you share data between components in Angular? Compare different approaches.
Should discuss @Input/@Output for parent-child, services with RxJS for siblings/unrelated, state management (NgRx, Signals) for complex apps. Look for choosing right pattern for complexity level.
Explain RxJS observables and common operators you use. How do you avoid memory leaks?
Should explain Observable, Subject, BehaviorSubject, common operators (map, switchMap, mergeMap, filter, debounceTime), and unsubscription strategies (async pipe, takeUntil, Subscription).
What are Angular signals? How do they differ from traditional state management approaches?
Should explain fine-grained reactivity, computed/effect, and how signals integrate with zoneless change detection. Look for understanding of Angular's evolution toward signal-based architecture.
How do you implement lazy loading in Angular? What are the benefits?
Should discuss loadChildren in routing, NgModules or standalone component approach, preloading strategies, and impact on initial bundle size. Look for practical optimization experience.
Explain dependency injection in Angular. What are the different provider scopes?
Should discuss constructor injection, @Injectable decorator, provider scopes (root, module, component), and tree-shakable providers. Look for understanding of singleton vs. instance DI.
How do you handle forms in Angular? Compare Template-driven vs. Reactive forms.
Should explain that Reactive forms offer more control, testability, and complex validation; Template-driven are simpler for basic forms. Look for choosing based on use case.
Describe Angular's build optimization techniques. How do you reduce bundle size?
Should mention AOT compilation, tree-shaking, lazy loading, bundle budgets, vendor chunk splitting, and analyzing with source-map-explorer. Look for practical optimization experience.
How do you test an Angular application? What testing strategies do you use?
Should discuss unit tests (Jasmine/Karma or Jest), component tests with TestBed, service tests with HTTP mocking, and e2e tests (Cypress/Playwright). Look for balanced testing approach.
Explain Angular routing. How do you implement route guards and resolvers?
Should discuss route configuration, RouterOutlet, guards (CanActivate, CanDeactivate, Resolve), and lazy loading. Look for practical examples of protecting routes and resolving data.
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