Core Angular Concepts
Components and Directives
Services and Dependency Injection
Modules
Routing
Forms
Observables and RxJS
Change Detection
Angular CLI
State Management
Performance Optimization
Testing
Angular Material and Tailwind CSS
Advanced Angular Concepts
Testing in Angular
Angular Performance and Optimization
Advanced Dependency Injection
Advanced Angular Scenarios and Topics
Angular Elements and Web Components
Server-Side Rendering (SSR) with Angular Universal
Security in Angular
Angular and Webpack
Angular Internationalization (i18n)
Angular Pipes
Angular Module Federation
State Management with NgRx (Advanced)
Angular Performance Optimization Techniques
Conclusion

Q1. What is Angular?
Angular is a TypeScript-based open-source web application framework developed by Google. It is used to build single-page applications (SPAs) with a focus on component-based architecture.

Q2. What are the key differences between AngularJS and Angular 2+ (including Angular 18)?

AngularJS is based on JavaScript, while Angular 2+ (including Angular 18) is based on TypeScript.
AngularJS uses a two-way data binding, while Angular 2+ employs a unidirectional data flow.
The architecture of Angular 2+ is based on components, whereas AngularJS relies heavily on controllers and scopes.
Angular 2+ offers better performance, a mobile-first approach, and a more modular structure.

Q3. Explain the component-based architecture in Angular.
Angular applications are built using components. Each component represents a self-contained block of UI and logic, encapsulating functionality and making the app modular, reusable, and maintainable.

Q4. What is the role of TypeScript in Angular?
TypeScript is a superset of JavaScript that adds static typing, classes, interfaces, and other features. Angular uses TypeScript for enhanced code maintainability, better tooling support, and faster development.

Q5. How do you create a new Angular project using the Angular CLI?
Run the following command in your terminal:

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ng new my-angular-project

This creates a new Angular project named my-angular-project with all the required files and configurations.

2. Components and Directives

Q6. What is a component in Angular?
A component is the fundamental building block of an Angular application. It controls a patch of the screen called a view. Each component has its own template, styles, and logic.

Q7. What are decorators in Angular?
Decorators are functions that modify the behavior of classes or properties. They are prefixed with @ and are used to define metadata for Angular classes like components, directives, and services.

Q8. How do you create a new component using Angular CLI?
Run the following command:

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ng generate component my-component

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ng g c my-component

Q9. What is a directive in Angular?
A directive is a class that allows you to extend or manipulate the behavior of elements in the DOM. Angular provides structural directives like *ngIf and *ngFor and attribute directives like [ngClass] and [ngStyle].

Q10. Explain the difference between @Component and @Directive decorators.

@Component is used to define a component with a template, styles, and logic.
@Directive is used to create a directive that can modify DOM elements but does not have a template.

3. Services and Dependency Injection

Q11. What is a service in Angular?
A service is a reusable piece of logic that can be shared across components. It is typically used for data fetching, business logic, or interacting with APIs.

Q12. How do you create a service using the Angular CLI?
Run the following command:

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ng generate service my-service

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ng g s my-service

Q13. What is Dependency Injection (DI) in Angular?
DI is a design pattern that allows classes to request dependencies from an injector instead of creating them. This promotes flexibility, testability, and cleaner code.

Q14. How do you provide a service in an Angular module?
You can provide a service by including it in the providers array of a module or by using providedIn: ‘root’ in the @Injectable() decorator for tree-shakable services.

4. Routing

Q15. What is the Angular Router?
The Angular Router is a service that provides navigation and URL manipulation capabilities in Angular applications. It allows you to build Single Page Applications (SPAs) with navigation between views.

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Q16. How do you configure routes in an Angular application?
To configure routes, you create an array of route objects, each defining a path and the component to render when that path is visited. You then pass this array to RouterModule.forRoot() (in the root module) or RouterModule.forChild() (in feature modules). Example:

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const routes: Routes = [

{ path: ‘home’, component: HomeComponent },

{ path: ‘about’, component: AboutComponent }

];

@NgModule({

imports: [RouterModule.forRoot(routes)],

exports: [RouterModule]

})

export class AppRoutingModule { }

Q17. What is a wildcard route?
A wildcard route is used to handle undefined paths. It matches any URL that hasn’t been matched by any defined routes and is often used to display a “404 — Not Found” page:

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{ path: ‘**’, component: PageNotFoundComponent }

Q18. How do you pass route parameters?
You can pass parameters in a route using a colon in the path definition:

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{ path: ‘user/:id’, component: UserComponent }

To access the parameter in the component:

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this.route.snapshot.paramMap.get(‘id’);

Q19. What is route guard?
Route guards are services that decide whether a route can be activated or deactivated. Angular offers built-in guards like CanActivate, CanDeactivate, CanActivateChild, CanLoad, and Resolve to control navigation.

5. Forms

Q20. What are the types of forms in Angular?
Angular provides two types of forms: Template-driven forms and Reactive forms.

Q21. Explain template-driven forms.
Template-driven forms rely on directives in the HTML template to create and validate forms. They are simpler but offer less control compared to reactive forms. They use ngModel for two-way data binding.

Q22. What are reactive forms?
Reactive forms are more flexible and offer greater control than template-driven forms. They are defined in the component class using FormControl, FormGroup, and FormArray and are useful for complex forms and dynamic form generation.

Q23. How do you create a form group in a reactive form?

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import { FormGroup, FormControl } from ‘@angular/forms’;

this.form = new FormGroup({

name: new FormControl(‘’),

email: new FormControl(‘’)

});

Q24. How do you perform form validation?
You can add validators to form controls using Angular’s built-in validators or custom validators:

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import { Validators } from ‘@angular/forms’;

this.form = new FormGroup({

email: new FormControl(‘’, [Validators.required, Validators.email])

});

6. Observables and RxJS

Q25. What is an Observable in Angular?
An Observable is a data stream that allows asynchronous data flow and handles events over time. Angular uses Observables extensively, especially for HTTP requests and form interactions, through RxJS (Reactive Extensions for JavaScript).

Q26. How do you subscribe to an Observable?
Use the subscribe() method to observe data emitted by an Observable:

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this.myObservable.subscribe(data => {

console.log(data);

});

Q27. What is the purpose of RxJS operators?
RxJS operators are used to transform, filter, and compose Observables. Examples include map, filter, mergeMap, switchMap, and take.

Q28. Explain the difference between switchMap and mergeMap.

switchMap cancels any previous ongoing subscription when a new value is emitted, making it suitable for scenarios where you need to handle only the latest request.
mergeMap allows all emissions to continue, combining multiple Observables into one.

Q29. How do you handle errors in an Observable?
You can handle errors using the catchError operator:

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this.http.get(‘api/data’).pipe(

catchError(error => {

console.error(‘Error occurred:’, error);

return throwError(error);

})

);

7. Change Detection

Q30. What is change detection in Angular?

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Change detection is the process by which Angular determines if the view needs to be updated in response to changes in data or user interactions.

Q31. How does Angular’s change detection strategy work?
Angular provides two change detection strategies: Default and OnPush. The Default strategy runs change detection on every change, while OnPush runs change detection only when input properties change.

Q32. What is the purpose of ngZone?
ngZone helps Angular detect changes outside of Angular’s scope, such as those triggered by asynchronous tasks (e.g., setTimeout, Promise resolution).

8. Angular CLI

Q33. What is the Angular CLI?
The Angular CLI (Command Line Interface) is a powerful tool for creating and managing Angular projects, generating components, and running build tasks.

Q34. How do you update an Angular project to the latest version?
Use the following command:

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ng update @angular/core @angular/cli

Q35. What is ng build?
The ng build command compiles your Angular project into an output directory (dist/) and optimizes the application for production by minifying and bundling files.

9. State Management

Q36. What is state management in Angular?
State management refers to handling the state (data) of your application. In complex applications, using a centralized state management solution like NgRx or Akita helps manage state more predictably.

Q37. What is NgRx?
NgRx is a library for reactive state management in Angular applications, inspired by Redux. It uses actions, reducers, and selectors to manage and query state.

Q38. Explain the difference between local state and global state.

Local state is specific to a component and used only within that component.
Global state is shared across multiple components, often managed using state management libraries like NgRx.

10. Performance Optimization

Q39. How do you optimize an Angular application?

Use the OnPush change detection strategy where applicable.
Employ lazy loading for modules.
Use Angular’s built-in async pipe to avoid manual subscriptions.
Minimize the size of bundle files using tree-shaking and AOT (Ahead-of-Time) compilation.
Avoid deep component trees by splitting large components.

Q40. What is lazy loading in Angular?
Lazy loading is a technique that loads modules only when they are needed, reducing the initial load time of an application.

11. Testing

Q41. What testing frameworks does Angular support out-of-the-box?
Angular supports unit testing with Jasmine and Karma, and end-to-end (e2e) testing with Protractor (though Cypress is becoming a popular choice).

Q42. What is the purpose of a spec.ts file?
spec.ts files contain unit tests for Angular components, services, and other logic. They follow the *.spec.ts naming convention.

12. Angular Material and Tailwind CSS Integration

Q43. What is Angular Material?
Angular Material is a UI component library for Angular developers that follows Google’s Material Design guidelines. It provides reusable, well-tested components like buttons, cards, input fields, data tables, etc., for building user interfaces quickly.

Q44. How do you add Angular Material to a project?
You can add Angular Material using the Angular CLI with the following command:

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ng add @angular/material

This installs Angular Material and sets up some configurations like themes and animations.

Q45. What are themes in Angular Material?
Themes define the colors and typography of Material components. Angular Material provides pre-built themes and allows customization through Sass variables.

Q46. How can you override Angular Material styles using Tailwind CSS?
You can override Angular Material styles with Tailwind CSS by applying Tailwind utility classes directly to Material components. Ensure you use Tailwind’s utility classes after Material styles to maintain specificity.

Q47. What are the advantages of using Tailwind CSS with Angular?

Utility-first approach: Tailwind provides utility classes, reducing the need for custom CSS and making styling faster.
Customization: Tailwind allows extensive customization, enabling fine control over design elements.
Responsive design: Tailwind’s built-in responsiveness makes creating mobile-first designs simple.
Component Styling: When using Tailwind CSS with Angular, you can style components easily without conflicting with other styles.

Q48. What is Flowbite, and how is it used with Tailwind CSS in Angular?
Flowbite is a Tailwind CSS component library that offers ready-to-use UI elements. You can integrate it into Angular by installing it as a dependency and using its components as you would use Angular Material components.

13. Advanced Angular Concepts

Q49. What is Ahead-of-Time (AOT) Compilation?
AOT compilation is a process that compiles Angular HTML templates and TypeScript code during the build process, producing smaller, faster applications by detecting template errors early and reducing runtime compilation.

Q50. What is ViewEncapsulation in Angular?
View encapsulation determines how styles are applied to components. Angular provides three encapsulation strategies:

Emulated (default): Emulates shadow DOM behavior by adding scoped styles.
None: No encapsulation; styles affect the whole document.
ShadowDom: Uses native shadow DOM for encapsulation.

Read More Here: https://blog.softwaretechit.com/2024/11/top-100-angular-18-interview-questions.html

Read More : https://blog.softwaretechit.com/2024/11/top-100-angular-18-interview-questions.html

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Top 100 Angular 18 Interview Questions (With Detailed Answers)

Table of Contents:

2. Components and Directives

3. Services and Dependency Injection

4. Routing

5. Forms

6. Observables and RxJS

7. Change Detection

8. Angular CLI

9. State Management

10. Performance Optimization

11. Testing

12. Angular Material and Tailwind CSS Integration

13. Advanced Angular Concepts

Written by SoftwareTechIT