Top 85 Angular Interview Questions With Answers For 2024

Angular Developers are sought after in various industries, enjoying consistently high demand for their skills. This demand is driven by the valuable contributions these developers make in their work. As a result, they receive competitive salaries across the globe.

If you’re applying for a job as an angular developer, it’s important that you go through the most commonly asked angular interview questions along with sample answers. Recruiters in 2024 assess you based on the quality of your answers and your breadth of knowledge.

This article will cover all topics related to angular development, regardless of whether you’re a beginner or experienced. Use it as a guide or a go-through doc to brush up your skills just before the interview.

30 Basic Angular Interview Questions With Sample Answers

Here are the 30 most common angular interview questions with answers you can use.

1. What is Angular, and how does it differ from AngularJS?

Angular is a TypeScript-based open-source front-end web application framework developed by Google. It's a complete rewrite of AngularJS, introducing features like a component-based architecture, better performance with ahead-of-time (AOT) compilation, and improved dependency injection.

Feature	Angular	AngularJS
Architecture	Component-based	Controller-based
Language	TypeScript (superset of JavaScript)	JavaScript (ES5)
Rendering	Uses real DOM and Virtual DOM	Uses two-way data binding with real DOM
Dependency Injection	Hierarchical Injector	Global Injector
Mobile Support	Improved support for mobile devices	Limited mobile support
Compilation	Ahead-of-Time (AOT) compilation	Just-In-Time (JIT) compilation
Performance	Generally better performance due to AOT and other optimizations	May face performance challenges, especially in larger applications
Two-way Data Binding	Supported with [(ngModel)] syntax	Achieved using `ng-model` directive
Scope	No `$scope`, uses component-based scope	Uses `$scope` for data binding and controller communication
Directives	Component-based, attribute, structural, and custom directives	Primarily attribute-based directives
Testing	Built-in testing utilities (e.g., TestBed)	Limited built-in testing support, often requires external libraries like Jasmine
Modularity	Modules (NgModule) for organizing code	Less emphasis on modular design
Development Tool	Angular CLI for streamlined development	Limited tooling, not as extensive as Angular CLI
Release Year	First released in 2016 (Angular 2)	Initial release in 2010 (AngularJS)

2. Explain the Angular component lifecycle hooks.

Angular components have several lifecycle hooks that allow developers to tap into the lifecycle of a component. Some key hooks include ngOnInit (called after the first ngOnChanges), ngOnChanges (called when an input binding value changes), and ngOnDestroy (called before the component is destroyed).

3. What is Angular CLI, and how does it streamline development?

Angular CLI (Command Line Interface) is a command-line tool for initializing, developing, scaffolding, and maintaining Angular applications. It automates tasks like project setup, component generation, and testing, providing a consistent and efficient development workflow.

4. How does data binding work in Angular? Explain one-way and two-way data binding.

Data binding is a powerful feature in Angular. One-way data binding involves binding data from the component to the view (using interpolation or property binding), while two-way data binding combines property binding and event binding, allowing automatic synchronization between the view and the model.

5. What is Angular Dependency Injection and why is it important?

Angular Dependency Injection is a design pattern where components and services are given their dependencies rather than creating or managing them internally. It promotes code modularity, testability, and maintainability by making components and services more independent and reusable.

6. Explain the role of NgModule in Angular.

NgModule is a decorator used to define a module in Angular. It helps organize the application into cohesive blocks, providing metadata about the module, such as which components, directives, pipes, and services belong to it. NgModule simplifies the organization and loading of features in Angular applications.

7. What is Angular Routing and how is it implemented?

Angular Routing is a mechanism that allows navigation from one view to another in a single-page application. It is implemented by defining routes, associating each route with a specific component, and using the Angular router to navigate between these components. Routes can be configured with parameters and guards for more advanced navigation control.

8. What are Angular services, and how do they differ from components?

Angular services are singleton objects that perform tasks common to multiple components. They are used to share data, logic, or functionality across different parts of an application. Services are distinct from components as they don't have a UI and are designed to be reusable, promoting a modular and maintainable codebase.

9. Explain the concept of Angular directives. Provide examples of built-in directives.

Angular directives are markers on a DOM element that tell Angular to do something with that element. Built-in directives include structural directives like ngIf (conditionally displaying elements) and ngFor (repeating elements based on an iterable), and attribute directives like ngStyle (applying styles based on conditions) and ngClass (adding or removing CSS classes dynamically).

10. What are Angular pipes, and how do they transform data in templates?

Angular pipes are used to transform and format data in templates. They are applied in the HTML using the pipe operator (|). Examples include {{ dateValue | date: 'short' }} to format a date and {{ stringValue | uppercase }} to convert a string to uppercase. Custom pipes can also be created for more specific transformations.

11. What are the advantages of using Angular?

Here are 10 advantages of using Angular:

1. Modular Development: Angular promotes a modular structure for organized and reusable code.

2. Two-way Data Binding: Simplifies synchronization between the model and the view, reducing boilerplate code.

3. Component-Based Architecture: Encourages the development of reusable and maintainable UI components.

4. Dependency Injection: Facilitates the creation of loosely coupled and testable components and services.

5. TypeScript Language: Enhances code quality, catches errors early, and improves developer productivity.

6. Powerful Templating: Enables dynamic views with expressive and clean HTML templates.

7. Cross-Browser Compatibility: Ensures consistent application behavior across different browsers.

8. Built-in Directives and Pipes: Provides convenient tools for common tasks in templates.

9. CLI (Command Line Interface): Automates project setup, component generation, and testing for a streamlined workflow.

10. Rich Ecosystem and Community Support: Offers a strong ecosystem, libraries, and an active community for ongoing support and improvements.

12. What is TypeScript? Why is it used?

TypeScript is a superset of JavaScript that adds static typing and other features to enhance code quality and maintainability.

It is used in Angular for the following reasons:

• Static Typing: Helps catch errors during development.
• Enhanced IDE Support: Enables better code navigation and autocompletion.
• Improved Readability: Type annotations make code more understandable.

13. What do you mean by Single Page Applications (SPAs)?

Single Page Applications (SPAs) are web applications that load a single HTML page and dynamically update the content as the user interacts with the app. Angular supports SPAs by dynamically updating views based on user actions without requiring full-page reloads.

14. What are the types of decorators in Angular?

In Angular, there are four types of decorators:

Decorator	Purpose
@Component	Defines a component and its metadata.
@Directive	Declares a directive and its metadata.
@Pipe	Marks a class as a pipe and defines its behavior.
@Injectable	Marks a class as available to be injected as a dependency.

15. What are some recent updates in Angular?

The recent updates in Angular V17 are as follows:

• TypeScript 5.2+ required.
• Ivy as the default rendering engine.
• Stricter equality checks in NgSwitch.
• Deprecated AnimationDriver.NOOP, use NoopAnimationDriver.
• Changes to Zone.js deep imports.
• URL parsing errors handled in UrlSerializer.parse.
• Improved performance and developer experience.

16. What are the most common change detection strategies?

Angular uses the following change detection strategies:

Strategy	Description
Default (CheckAlways)	Checks all components on every change detection cycle.
OnPush	Checks components only when input properties change or events are triggered.
Detached	No automatic checks, developers manually trigger change detection.

17. Why is lazy loading required in modules?

Lazy loading in Angular is essential for improving application performance by loading modules only when they are needed. This reduces the initial loading time of the application and enhances the user experience. Lazy loading is achieved using the loadChildren property in the route configuration.

18. What do you mean by templates in Angular?

In Angular, templates define the view of a component and are written in HTML with additional Angular-specific syntax. Templates include data-binding expressions, directives, and other features that Angular uses to render dynamic content.

Here's a basic example:

<div>{{ greeting }}</div>

19. What is ngIf directive?

The ngIf directive in Angular is a structural directive that conditionally renders elements based on the truthiness of an expression. It is commonly used for showing or hiding elements in the template.

Example:
<div *ngIf="isLoggedIn">Welcome, User!</div>

20. What are some common custom elements?

Custom elements in Angular are components. Here are some common examples:

Custom Element	Description
<app-header>	Custom header component.
<app-footer>	Custom footer component.
<app-user-profile>	Component for displaying user profile details.
<app-product-list>	Component for displaying a list of products.

These custom elements are Angular components that encapsulate specific functionality or UI elements.

21. How to use HTTPClient?

• Import HttpClientModule: In your app.module.ts, import the HttpClientModule.
• Inject HttpClient: Inject the HttpClient service into your component's constructor.
• Make HTTP requests: Use the methods like get, post, put, etc., to send requests to REST APIs.
• Handle response: Subscribe to the returned observable using rxjs operators like tap, map, catchError, etc. to process the response and handle errors.

import { HttpClient } from '@angular/common/http'; 
 
@Component({ 
  selector: 'app-my-component', 
  template: ` 
    <p>Data: {{ data$ | async }}</p> 
  `, 
}) 
export class MyComponent { 
  data$: Observable<any>; 
 
  constructor(private http: HttpClient) { 
    this.data$ = this.http.get('https://api.example.com/data').pipe( 
      tap(data => console.log('Data fetched:', data)), 
      catchError(error => of('Error fetching data')) // Handle errors 
    ); 
  } 
} 

22. What is REST used for?

• RESTful API design: A set of architectural principles for designing web APIs.
• Web data transfer: Provides a standard way to access and manipulate data over HTTP.
• CRUD operations: Enables common actions like Create, Read, Update, Delete on resources.
• JSON data exchange: Uses JSON for data representation, often for complex objects.

23. How is Error Handling performed?

• catchError operator: Catch and handle errors returned by observables using catchError.
• Response status codes: Check HTTP status codes like 404 (Not Found) or 500 (Internal Server Error) to provide specific error messages.
• Custom error handling services: Create services to centralize error handling logic and provide global notifications.

this.http.get('https://api.example.com/data').pipe( 
  catchError(error => { 
    if (error.status === 404) { 
      return of('Data not found'); // Customize error message 
    } else { 
      // Handle other errors differently 
    } 
  }) 
); 

24. Why would a person use AOT compilation?

• Improved performance: Pre-compiles templates and styles into JavaScript code, reducing runtime overhead.
• Smaller bundle size: Only necessary code is included, leading to faster downloads and loading times.
• Better SEO: Search engines can directly index statically rendered HTML content.
• Catching errors early: Compile-time errors are detected in development, not when the app runs.

25. Explain Components in Angular.

• Building blocks of Angular applications: Reusable UI elements with templates, styles, and logic.
• Decoupled communication: Interact with each other via inputs, outputs, and events.
• Data binding: Synchronize component data with the template for dynamic updates.
• Lifecycle hooks: Run code at specific stages (e.g., initialization, destruction) for managing component behavior.

@Component({ 
  selector: 'app-my-component', 
  template: ` 
    <h1>{{ title }}</h1> 
    <p>{{ description }}</p> 
  `, 
}) 
export class MyComponent { 
  title = 'My Component'; 
  description = 'This is a simple Angular component.'; 
} 

26. Give an example of PipeTransform interface.

import { Pipe, PipeTransform } from '@angular/core'; 
 
@Pipe({ 
  name: 'customCurrency' 
}) 
export class CustomCurrencyPipe implements PipeTransform { 
  transform(value: number, currencySymbol: string = '$'): string { 
    return `${currencySymbol}${value.toFixed(2)}`; 
  } 
} 

27. Differentiate between pure and impure pipes.

Pure pipes: Don't have side effects and produce the same output for the same input, making them predictable and efficient for caching.

Impure pipes: Can have side effects (e.g., accessing external data) and might produce different outputs based on external factors, requiring manual change detection.

Feature	Pure Pipes	Impure Pipes
Execution Frequency	Limited: Called only when the input values change.	Frequent: Called on every change detection cycle.
Caching	Caching Enabled: Results are cached for efficient reuse.	No Caching: Results are recalculated on every change detection.
State Changes	No Side Effects: Pure pipes don't modify external state.	May Have Side Effects: Impure pipes can modify external state.
Usage	Recommended: For stateless transformations.	Use with Caution: Use when stateful transformations are necessary, but consider alternatives.

28. Name a few filters in Angular.

• async: Converts promise-based values to observables.
• date: Formats dates according to specified patterns.
• json: Converts objects to JSON strings.
• lowercase: Converts

29. Why are template statements used? Give example.

Templates are mainly used for the following reasons:

• Build UI declaratively.
• Data binding for dynamic updates.
• Event handling for user interaction.

Example:

<h2>Welcome, {{ name }}!</h2> 
<button (click)="changeName()">Change</button> 

30. What do you mean by ngModule?

An NgModule is the cornerstone of organization in Angular applications. It brings together related code and defines how it interacts with itself and the larger application. It's like a mini-app within your app, promoting modularity and maintainability.

Example:

@NgModule({ 

  declarations: [AppComponent], 

  bootstrap: [AppComponent] 

}) 

export class AppModule {} 

30 Intermediate Level Interview Questions for Angular with Sample Answers and Important Concepts

31. Explain the difference between ngDoCheck and ngOnInit lifecycle hooks.

Hook	Description
ngDoCheck	Called after every change detection cycle due to any change (even internal ones).
ngOnInit	Called only once, after the view and child views are initialized.

32. How would you implement server-side rendering (SSR) in your Angular application?

1. Use Angular Universal to pre-render components on the server for SEO and initial load performance.

2. Configure your web server to serve the pre-rendered HTML with embedded JavaScript.

33. Describe the advantages and disadvantages of using lazy loading.

Advantage	Disadvantage
Reduces initial bundle size	Requires additional code splitting logic and route configuration.
Improves perceived performance	Increases complexity and adds HTTP requests for lazy-loaded modules.

34. What are the key differences between @Input and @Output decorators?

Decorator	Purpose
@Input	Passes data from parent to child component.
@Output	Emits events from child to parent component.

35. How would you debug an HTTP request that's failing in your Angular application?

1. Use browser developer tools (Network tab) to inspect the request/response.

2. Log request/response details in your component or service.

3. Enable Angular's HttpClient debug mode for detailed logging.

36. Can you provide an example of using a custom pipe to format currency?

// currency.pipe.ts  

  

@Pipe({ name: 'currency' })  

export class CurrencyPipe implements PipeTransform {  

  transform(value: number, currencySymbol = '$'): string {  

    return `${currencySymbol}${value.toFixed(2)}`;  

  }  

}  

  

// app.component.ts  

  

@Component({  

  // ...  

})  

export class AppComponent {  

  price = 123.45;  

}  

  

// app.component.html  

  

<p>Price: {{ price | currency }}</p>  

37. How do you ensure your Angular application is accessible to users with disabilities?

1. Describe using semantic HTML tags and ARIA attributes.

2. Mention tools like Lighthouse and WAVE for accessibility audits.

3. Highlight techniques like focus management and keyboard navigation.

38. What are the common approaches to handle authentication and authorization in an Angular application?

• Explain JWT-based authentication with token storage and verification.

• Discuss using services like Auth0 or Firebase Authentication.

• Briefly mention role-based access control (RBAC) techniques.

39. How do you implement state management in your Angular applications?

1. Compare NgRx and MobX and their use cases.

2. Briefly explain the concept of actions, reducers, and selectors.

3. Discuss choosing the right state management solution based on complexity and requirements.

40. Describe different strategies for testing Angular components and services.

• Unit testing with Angular TestBed and Jasmine.

• Integration testing with Karma and end-to-end testing with tools like Cypress or Protractor.

• Unit and integration testing for code quality.

41. How can you optimize the performance of an Angular application?

• Code splitting and lazy loading for reducing bundle size.

• Techniques like change detection optimization and using NgCD.

• Browser caching and image optimization strategies.

42. Can you demonstrate using an observable with operators like map, filter, and catchError in your code?

// example.component.ts  

  

import { Component } from '@angular/core';  

import { Observable, of, throwError } from 'rxjs';  

import { map, filter, catchError } from 'rxjs/operators';  

  

@Component({  

  // ...  

})  

export class ExampleComponent {  

  fetchData(): Observable<string> {  

    return this.http.get<string>('https://api.example.com/data').pipe(  

      map(data => data.toUpperCase()), // Convert to uppercase  

      filter(data => data.length > 5), // Filter results  

      catchError(error => of('Error fetching data')) // Handle errors  

    );  

  }  

}  

43. Explain the Zone.js and its role in Angular applications.

Zone.js is a library that acts as a virtual zone, intercepting asynchronous operations like DOM manipulations and event handling. It enables Angular to keep track of changes and trigger change detection efficiently. By wrapping these operations within the Zone, Angular ensures consistent data binding and reactivity behavior, even in the presence of asynchronous operations.

44. Differentiate between Ahead-of-Time (AOT) and Just-in-Time (JIT) compilation in Angular.

Both AOT and JIT compile Angular code into JavaScript, but they do it at different stages:

AOT: Compilation happens during the build process, resulting in smaller bundle sizes, improved performance, and better SEO due to pre-rendered HTML.

JIT: Compilation occurs at runtime in the browser, leading to easier development and debugging but potentially larger bundle sizes and slight performance drawbacks.

45. How does dependency injection work in Angular, and what are its benefits?

Dependency injection promotes loose coupling between components and services in Angular. Instead of manually creating dependencies, you declare them in component constructors or service providers. Angular then injects the necessary instances at runtime. This approach enhances testability, maintainability, and flexibility as dependencies can be easily swapped or modified.

46. Describe the Angular router and its main components.

The Angular router helps manage navigation between different views in your application.

It consists of:

• Routes: Define the mapping between URLs and components.

• RouterLink directive: Used in templates to define navigation links.

• Router service: Provides programmatic navigation access.

• Navigation events: Emitted during navigation, allowing components to react to route changes.

47. Explain the concept of change detection and its strategies in Angular.

Change detection is the mechanism by which Angular keeps the view synchronized with the data model. It automatically runs when certain events occur (e.g., user interaction, data changes).

Angular offers various strategies for optimizing change detection:

• Default: Change detection runs recursively down the component tree.

• OnPush: Requires manual change detection triggering for performance benefits.

• ChangeDetectorRef: Provides fine-grained control over specific view updates.

48. Discuss the role of RxJS in Angular and its key operators.

RxJS, a reactive programming library, powers asynchronous operations in Angular. It enables you to handle streams of data over time using observables and operators.

Key operators include:

• map: Transforms data emitted by the observable

• filter: Selects specific data based on a condition

• tap: Performs side effects without altering the emitted data

• switchMap, concatMap: Handle sequences of asynchronous operations

• catchError: Gracesfully handle errors in the observable stream

49. Explain the concept of Angular Forms and their validation mechanisms.

Angular Forms provide mechanisms for creating data-driven forms with validation, ensuring user input integrity. You can create reactive forms using FormBuilder or template-driven forms using directives like ngModel. Both offer built-in validation directives like required, minLength, and custom validation approaches using validators. Understanding various validation strategies strengthens your forms' reliability and data accuracy.

51. Differentiate between Structural Directives and Attribute Directives in Angular.

Structural Directives: Dynamically manipulate the DOM structure like *ngIf, *ngFor, manipulating template content based on data or conditions.

Attribute Directives: Modify the behavior of existing HTML elements. Examples include [disabled], [class], altering element attributes or styles based on data.

52. Describe the Angular CLI (Command Line Interface) and its benefits.

The Angular CLI is a powerful toolset for creating, developing, and managing Angular projects.

It simplifies tasks like:

• Project generation

• Component, service, and other file creation

• Running the development server

• Building for production

• Testing functionalities

• Utilizing the CLI enhances development efficiency and streamlines common tasks, saving you time and effort.

53. Explain the principle of immutability in Angular and its advantages.

Immutability refers to creating and modifying data without altering the original object. Following immutability practices leads to predictable data changes, simplifies debugging, and promotes safer state management in your Angular applications.

In Angular, you can achieve this using:

• Immutability libraries like Immutable.js

• Spread syntax to create new objects with modifications

• Object.freeze to prevent further changes

54. Implement a pipe to format numbers as currency with a custom symbol.

@Pipe({ name: 'currency' })  

export class CurrencyPipe implements PipeTransform {  

  transform(value: number, symbol = '$'): string {  

    return `${symbol}${value.toFixed(2)}`;  

  }  

}  

55. Use HttpClientModule to fetch data and display it in a component.

// Component:  

  

@Component({ /* ... */ })  

export class DataComponent implements OnInit {  

  data: any;  

  

  constructor(private http: HttpClient) {}  

  

  ngOnInit() {  

    this.http.get('https://api.example.com/data')  

      .subscribe(data => (this.data = data));  

  }  

}  

// Template:  

  

<p *ngIf="data">{{ data.name }}</p>  

<p *ngIf="data">{{ data.email }}</p>  

56. Emit an event from a child component and subscribe to it in a parent component.

// Parent:  

  

@Component({ /* ... */ })  

export class ParentComponent {  

  @Output() eventEmitted = new EventEmitter<string>();  

  

  handleEvent(data: string) {  

    console.log('Received event from child:', data);  

  }  

}  

// Child:  

  

@Component({ /* ... */ })  

export class ChildComponent {  

  emitEvent() {  

    this.eventEmitted.emit('Data from child');  

  }  

}  

57. Display a list of items using *ngFor.

HTML  

  

<ul>  

  <li *ngFor="let item of items">{{ item.name }}</li>  

</ul>  

  

TypeScript  

  

items = [{ name: 'Item 1' }, { name: 'Item 2' }, { name: 'Item 3' }];  

58. Implement basic form validation with ngModel.

HTML  

  

<form>  

  <input type="text" [(ngModel)]="username" required>  

  <span *ngIf="!username && submitted">Username required.</span>  

  <button (click)="onSubmit()">Submit</button>  

</form>  

  

  

TypeScript  

  

username: string = '';  

submitted = false;  

  

onSubmit() {  

  this.submitted = true;  

  if (this.username) {  

    // handle submission  

  }  

}  

59. Use a service to share data between components.

TypeScript  

  

// Service:  

  

@Injectable({ providedIn: 'root' })  

export class DataService {  

  private data: string = 'Initial data';  

  

  setData(newData: string) {  

    this.data = newData;  

  }  

  

  getData() {  

    return this.data;  

  }  

}  

  

// Components:  

  

// Component 1 sets data  

// Component 2 retrieves and displays data  

60. Implement basic routing with the Angular Router.

TypeScript  

  

// app-routing.module.ts:  

  

const routes: Routes = [  

  { path: '', component: HomeComponent },  

  { path: 'about', component: AboutComponent },  

];  

  

@NgModule({  

  imports: [RouterModule.forRoot(routes)],  

  exports: [RouterModule],  

})  

export class AppRoutingModule { }  

HTML  

  

<a routerLink="/">Home</a>  

<a routerLink="/about">About</a>  

  

<router-outlet></router-outlet>  

25 Advanced Level Interview Questions For Angular With Sample Answers

61. What is the method for applying pagination with Angular?

Pagination in Angular is commonly achieved by using the built-in ngx-pagination library or by implementing custom pagination logic. The library provides a simple way to paginate data in Angular applications.

62. Which browsers support Angular Elements?

Angular Elements are designed to work in all modern browsers, including Google Chrome, Mozilla Firefox, Microsoft Edge, Safari, and more. Angular Elements leverage web standards and work seamlessly in browsers that support Custom Elements.

63. What are the different Angular Directives?

Angular Directives include:

• Structural Directives: Modify the structure of the DOM (e.g., ngIf, ngFor).

• Attribute Directives: Change the appearance or behavior of an element (e.g., ngStyle, ngClass).

• Custom Directives: Created by developers for specific functionality.

64. Why would you use CommonModule in Angular?

CommonModule in Angular is used in feature modules to import common directives such as NgIf and NgFor without importing the full set of browser-related services. It avoids redundancy and ensures proper module encapsulation.

65. Differentiate between JavaScript and Angular expressions.

• JavaScript Expressions: Code snippets that produce values. Often involve complex logic.

• Angular Expressions: Similar to JavaScript, but more restricted. Mainly used in templates for data binding and interpolation.

66. What is MVVM architecture? Explain in simple words.

MVVM (Model-View-ViewModel) is an architectural pattern where the Model represents the data, the View displays the data, and the ViewModel acts as an intermediary that handles communication between the Model and View, providing data for display.

67. Why are class decorators used?

Class decorators in Angular are used to annotate and modify classes at design time. They allow developers to extend or alter the behavior of classes, often used for features like dependency injection, component metadata, and more.

68. How to determine router state in Angular?

In Angular, you can determine the router state by subscribing to the ActivatedRoute service. It provides information about the route, parameters, query parameters, and other details. Example:

typescript  

  

import { ActivatedRoute } from '@angular/router';  

  

   

  

// ...  

  

   

  

constructor(private route: ActivatedRoute) {  

  

  this.route.paramMap.subscribe(params => {  

  

    console.log(params.get('id'));  

  

  });  

  

}  

  

69. How to solve errors in observables?

Errors in observables can be handled using the .catch() or .pipe(catchError()) operators. Subscribers can then handle the error in the error callback.

70. What do you know about Sass files?

Sass (Syntactically Awesome Stylesheets) is a preprocessor scripting language that is interpreted or compiled into CSS. It adds features like variables, nesting, and mixins, enhancing the maintainability and readability of stylesheets.

71. How does the change detection mechanism work?

Angular's change detection mechanism checks for changes in the component's state. It compares the current state with the previous state and updates the DOM accordingly. Zones help Angular track asynchronous operations and trigger change detection when needed.

72. What are the methods used for getting and changing cookies?

• Getting Cookies: Use document.cookie to get all cookies and then parse as needed.

• Changing Cookies: Set a new cookie using document.cookie = "name=value; expires=date; path=path".

73. Give 3 use cases of ngcc.

• Updating Dependencies: ngcc updates Angular dependencies to their Ivy-compatible versions.

• Ensuring Compatibility: It ensures that third-party libraries using View Engine are compatible with Ivy.

• Ahead-of-Time (AOT) Compilation: ngcc is crucial for AOT compilation to work with Ivy.

74. Are there any security concerns of using Angular?

Angular itself provides strong security features, but developers need to be mindful of common web security issues such as cross-site scripting (XSS), cross-site request forgery (CSRF), and insecure API calls.

75. How will you improve security while using Angular?

• Sanitization: Use Angular's built-in sanitization functions to prevent XSS attacks.

• Secure API Calls: Use HTTPS, validate and sanitize input on the server, and implement proper authentication.

• Content Security Policy (CSP): Implement and enforce CSP headers to mitigate security risks.

76. Why is the State function used?

The term "State function" is broad, but in the context of front-end development or frameworks like React, a state function typically refers to a function used to manage and update the state of a component. It allows for dynamic changes in the user interface based on application logic.

77. What do you mean by NgZone?

NgZone is an Angular service that helps manage and facilitate change detection. It provides a way to execute code outside Angular's zone, which can be useful for handling asynchronous operations that might otherwise trigger unnecessary change detection cycles.

78. What do you know about bootstrapping modules?

Bootstrapping modules in Angular refers to the process of launching an Angular application by loading the root module. The AppModule is typically bootstrapped in the main.ts file, and it serves as the entry point for Angular to start building and rendering the application.

79. How do you optimize performance in Angular?

• Lazy Loading: Implement lazy loading for modules to load them only when needed.

• Ahead-of-Time (AOT) Compilation: Pre-compile templates during build for faster rendering in the browser.

• Minification and Tree Shaking: Minify code and remove unnecessary code (tree shaking) to reduce bundle size.

• Optimizing Change Detection: Use OnPush change detection strategy, and avoid unnecessary change detection cycles.

80. Why is ngFor trackBy used?

ngFor with trackBy is used to improve the efficiency of Angular's change detection when dealing with lists or collections. It helps Angular identify which items have changed, added, or removed, resulting in better performance by avoiding unnecessary re-rendering of unchanged items.

81. What is a safe navigating operator?

The safe navigation operator (?.) is used in TypeScript and Angular templates to guard against null or undefined values. It allows for the safe access of properties or methods on potentially null or undefined objects without causing runtime errors.

82. Is it a requirement for the bootstrapped component to also serve as an entry component?

No, it is not a requirement. While the bootstrapped component is the starting point of the Angular application, it does not have to serve as an entry component. Entry components are components that are referenced in the application's templates, and they are not necessarily the same as the bootstrapped component.

83. What happens if BrowserModule is used in a feature module?

Using BrowserModule in a feature module will lead to errors during the compilation process. BrowserModule should only be imported in the root module to set up browser-specific services. Feature modules should use CommonModule for common directives and avoid importing BrowserModule to prevent conflicts.

84. Can services be shared using modules?

Yes, services can be shared across multiple modules by providing the service in a shared module and importing that module wherever the service is needed. This promotes code organization and reusability.

85. Does every service class require @Injectable?

No, not every service class requires the @Injectable decorator. It is needed when the service has dependencies that need to be injected or if the service itself is injected into other components or services. If a service is standalone and doesn't have dependencies, the decorator is optional. However, it's a good practice to include it for consistency.

Next Steps

To wrap it up, once you've got all those interview questions down, the next moves are to practice your presentation skills with mock interviews. Work on any weak spots, and get smooth with your answers to those behavior questions.

Do some detective work on the company, keep up with what's hot in the industry, and polish up your communication game. Don't forget to ask the interviewer some smart questions to show you're genuinely into it.

Stay on top of time and make sure you're all set with tech and stuff for a confident interview. Finally, a brief review of key concepts and relaxation techniques before the interview day can help boost confidence and overall performance.