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Top 20 Angular Interview Questions & Answers (2025 Edition)

Top 20 Angular Interview Questions & Answers (2025 Edition)

Prepare for your next Angular developer interview with these key concepts.

Angular Questions and Answers

1. What is Angular?
Angular is a front-end web application framework developed by Google. It’s built on TypeScript and is used to create single-page applications (SPAs). It provides features like dependency injection, data binding, routing, and component-based architecture.
2. What’s new in Angular 17–18 (2025 updates)?
Angular 17 introduced deferrable views, signal-based reactivity, and faster build performance. Angular 18 (expected in 2025) focuses on better integration with modern JavaScript runtimes and smaller bundle sizes.
3. What is a Component in Angular?
A Component is the basic building block of Angular apps. It controls a part of the user interface (UI) and contains HTML, CSS, and TypeScript code. Each component has:
  • A TypeScript class (logic)
  • An HTML template (view)
  • And an optional CSS file (style)
4. What are Directives in Angular?
Directives are special instructions in Angular templates.
  • Component directives — define custom components.
  • Structural directives — change DOM layout (e.g., *ngIf, *ngFor).
  • Attribute directives — change appearance or behavior of elements (e.g., [ngClass]).
5. Explain Dependency Injection (DI) in Angular.
Dependency Injection is a design pattern in which a class requests dependencies from external sources rather than creating them itself. Angular’s DI system provides services and injects them into components or other services as needed.
6. What is Data Binding?
Data Binding is a way to connect the component’s data with the template. Angular supports:
  • Interpolation — {{ data }}
  • Property binding — [property]="value"
  • Event binding — (event)="handler()"
  • Two-way binding — [(ngModel)]="value"
7. What is Routing in Angular?
Routing allows navigation between different components without reloading the page. The RouterModule defines routes and enables features like lazy loading and guards.
8. What are Angular Services?
Services are classes that contain reusable logic or data. They are typically used for communication with APIs, sharing data between components, or implementing business logic. They can be injected anywhere using Angular’s dependency injection system.
9. What is an Observable?
Observables (from RxJS) are used to handle asynchronous data streams. They’re often used in HTTP calls, event handling, and real-time updates.
10. What are Promises vs Observables?
  • Promise: Handles a single asynchronous value.
  • Observable: Can emit multiple values over time and supports operators like map, filter, and retry.
11. What are Pipes in Angular?
Pipes transform data in templates. For example: {{ user.name | uppercase }}. You can also create custom pipes using the @Pipe() decorator.
12. What are Lifecycle Hooks?
Lifecycle hooks are special methods that get called during different stages of a component’s life. Examples include:
  • ngOnInit() — Called once after the component is initialized.
  • ngOnChanges() — Called when data-bound properties change.
  • ngOnDestroy() — Called just before the component is removed.
13. What is an Angular Interceptor?
An interceptor can modify HTTP requests or responses. It’s commonly used for adding authentication tokens, handling errors globally, or showing loading indicators.
14. What are Guards in Angular?
Guards control navigation. They can allow or prevent access to routes. Common guards:
  • CanActivate — controls route access.
  • CanDeactivate — confirms before leaving a route.
15. What is Lazy Loading?
Lazy loading loads feature modules only when needed, improving app performance. It uses the loadChildren property in route definitions.
16. What are Signals in Angular (new in 2024–2025)?
Signals are a new reactivity model in Angular that replaces traditional change detection. They make data updates more predictable and efficient.
17. What is Standalone Component?
Introduced in Angular 14, standalone components allow creating components without needing a module. It simplifies app structure and reduces boilerplate.
18. How does Angular handle Forms?
Angular has two approaches for forms:
  • Template-driven forms — simpler, suitable for small forms.
  • Reactive forms — more powerful, uses FormGroup and FormControl.
19. What are Angular Signals vs RxJS Observables?
Signals are synchronous, track dependencies automatically, and trigger updates efficiently. Observables are asynchronous and stream-based. They can work together in Angular apps.
20. How do you improve Angular app performance?
- Use lazy loading for modules.
- Use OnPush change detection.
- Optimize bundle size using ng build --configuration production.
- Avoid unnecessary DOM manipulations.
- Use trackBy in *ngFor loops.

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