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Top Angular Interview Questions and Answers (2025) | RG Dimension

Top Angular Interview Questions and Answers (2025) | rgdimension

Top Angular Interview Questions and Answers (2025)

Angular developer preparing for interview

1. What is Angular?

Angular is a TypeScript-based open-source front-end web application framework developed by Google. It helps developers build scalable, dynamic, and responsive single-page applications (SPAs).

2. What are the key features of Angular?

  • Two-way data binding
  • Dependency Injection (DI)
  • Directives and Components
  • Routing and Navigation
  • Reactive Forms and Observables
  • TypeScript and RxJS support

3. What is a Component in Angular?

A Component is the basic building block of an Angular application. It controls a section of the user interface using HTML, CSS, and TypeScript.

import { Component } from '@angular/core'; @Component({ selector: 'app-hello', template: '<h1>Hello Angular</h1>', }) export class HelloComponent {}

4. What is Data Binding?

Data Binding is the mechanism that connects the application’s data with the UI. Angular supports:

  • Interpolation: {{ data }}
  • Property Binding: [property]="value"
  • Event Binding: (event)="handler()"
  • Two-way Binding: [(ngModel)]="value"

5. What are Directives?

Directives are special instructions in Angular templates that modify the DOM. They are of three types:

  • Component Directives – define UI and behavior.
  • Structural Directives – modify DOM layout (e.g., *ngIf, *ngFor).
  • Attribute Directives – change element appearance (e.g., ngClass, ngStyle).
<div *ngIf="isLoggedIn">Welcome User</div> <li *ngFor="let item of items">{{item}}</li>

6. What is Dependency Injection in Angular?

Dependency Injection (DI) is a design pattern where components receive their dependencies from an external source instead of creating them internally. Angular has a built-in DI framework that improves testability and flexibility.

constructor(private userService: UserService) {}

7. What are Services in Angular?

Services are classes that contain reusable business logic, often used for data sharing, API calls, or utility functions.

@Injectable({ providedIn: 'root' }) export class UserService { getUsers() { return ['Alice', 'Bob', 'Charlie']; } }

8. What is Routing in Angular?

Routing allows users to navigate between different components or views in a single-page application without reloading the page.

const routes: Routes = [ { path: 'home', component: HomeComponent }, { path: 'about', component: AboutComponent } ];

9. What is an Observable in Angular?

Observables are used to handle asynchronous data streams. They are part of RxJS and commonly used with HTTP requests, event handling, and reactive forms.

this.http.get('https://api.example.com/users') .subscribe(data => console.log(data));

10. What are Angular Modules?

Modules help organize code into functional units. Each Angular app has at least one root module (AppModule).

@NgModule({ declarations: [AppComponent], imports: [BrowserModule], bootstrap: [AppComponent] }) export class AppModule {}

11. What is Change Detection?

Change Detection is Angular’s process of updating the DOM when data changes. It automatically tracks data bindings and re-renders affected components.

12. What are Pipes in Angular?

Pipes transform data before displaying it in templates.

{{ user.name | uppercase }} {{ today | date:'longDate' }}

13. What is Lazy Loading?

Lazy loading allows you to load feature modules only when needed, improving performance and reducing initial load time.

const routes: Routes = [ { path: 'admin', loadChildren: () => import('./admin/admin.module').then(m => m.AdminModule) } ];

14. What are Guards in Angular Routing?

Route Guards control navigation and protect routes using conditions like authentication or permissions.

canActivate(): boolean { return this.authService.isLoggedIn(); }

15. Difference between AngularJS and Angular?

  • AngularJS: JavaScript-based, MVC architecture, uses $scope.
  • Angular: TypeScript-based, component-driven architecture, faster, supports RxJS and CLI.

Conclusion

Mastering Angular interview questions helps developers strengthen their fundamentals in components, data binding, RxJS, routing, and dependency injection. Whether you’re preparing for Angular 15, 16, or 17 interviews, understanding these core concepts will boost your confidence and success rate.

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