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Top 100 Angular 8 Interview Questions and Answers

Top 100 Angular 8 Interview Questions and Answers

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1. What is Angular 8?

Angular 8 is a TypeScript-based open-source framework for building web applications. It’s a complete rewrite of AngularJS, designed to make both the development and testing of such applications easier.

// Example of a basic Angular component
import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  template: '<h1>Hello World</h1>'
})
export class AppComponent { }

2. Explain the key differences between Angular and AngularJS.

Angular is a complete rewrite of AngularJS, introducing significant changes. It’s written in TypeScript, offers better performance, supports lazy loading, and employs a more component-based architecture.

// Example of a simple AngularJS controller
app.controller('myController', function($scope) {
  $scope.message = 'Hello World';
});

3. What are the improvements in Angular 8?

Angular 8 introduced various improvements including the Ivy rendering engine for better performance and smaller bundle sizes, differential loading for faster startup, and improved web worker support.

// Example of enabling Ivy rendering engine in angular.json
"angularCompilerOptions": {
  "enableIvy": true
}

4. Explain Ivy in Angular 8.

Ivy is Angular’s new compiler and rendering pipeline. It results in faster compilation times, smaller bundles, and improved debugging. It’s designed to replace the View Engine, the previous rendering engine.

// Example of enabling Ivy rendering engine in angular.json
"angularCompilerOptions": {
  "enableIvy": true
}

5. What is AOT compilation in Angular 8?

AOT (Ahead-of-Time) compilation is a process in which Angular compiles templates and components during the build process. This allows the application to render more quickly in the browser and offers better security.

// Example of enabling AOT compilation in angular.json
"angularCompilerOptions": {
  "fullTemplateTypeCheck": true,
  "strictInjectionParameters": true
}

6. What is Lazy Loading in Angular 8?

Lazy Loading is a technique used in Angular 8 to load modules on-demand, instead of loading the entire application at once. This can significantly improve initial loading times, especially for large applications.

// Example of lazy loading in Angular routing
const routes: Routes = [
  { path: 'lazy', loadChildren: './lazy/lazy.module#LazyModule' }
];

7. How do you create forms in Angular 8?

Angular 8 provides two approaches for creating forms: Template-driven forms and Reactive forms. Template-driven forms rely on directives within the template, while Reactive forms are model-driven and defined in the component.

// Example of a template-driven form
<form #myForm="ngForm">
  <input name="name" [(ngModel)]="user.name" required>
</form>

8. What is RxJS in Angular 8?

RxJS (Reactive Extensions for JavaScript) is a library for reactive programming using Observables. In Angular, it’s used extensively for handling asynchronous operations such as HTTP requests.

// Example of an Observable in Angular
import { Observable } from 'rxjs';

const myObservable = new Observable(observer => {
  observer.next('Hello World');
});

9. Explain the use of Angular CLI in Angular 8.

Angular CLI (Command Line Interface) is a command-line tool for creating, managing, and deploying Angular applications. It provides a set of commands to streamline the development process.

# Example of generating a new Angular component
ng generate component my-component

10. How do you handle HTTP requests in Angular 8?

Angular 8 provides a built-in module called HttpClientModule to handle HTTP requests. It simplifies making requests and processing responses.

// Example of making an HTTP GET request in Angular
import { HttpClient } from '@angular/common/http';

constructor(private http: HttpClient) {}

getData() {
  return this.http.get('/api/data');
}

11. What is the use of decorators in Angular 8?

Decorators in Angular 8 are functions that modify JavaScript classes. They are used to enhance or modify the behavior of classes, methods, or properties.

// Example of using a decorator in Angular
@Component({
  selector: 'app-root',
  template: '<h1>Hello World</h1>'
})
export class AppComponent { }

12. What is Dependency Injection in Angular 8?

Dependency Injection (DI) is a design pattern used in Angular 8 to manage dependencies between different parts of an application. It allows components and services to receive dependencies rather than creating them.

// Example of injecting a service in Angular component
constructor(private dataService: DataService) {}

13. Explain the difference between ngOnChanges and ngOnInit.

ngOnChanges is a lifecycle hook in Angular that is called when any data-bound property of a directive changes. ngOnInit is called once after the first ngOnChanges.

// Example of using ngOnChanges and ngOnInit
ngOnChanges(changes: SimpleChanges) {
  // React to changes
}

ngOnInit() {
  // Initialization logic
}

14. What is Angular Universal in Angular 8?

Angular Universal is a technology that allows rendering Angular applications on the server side, which improves performance and SEO. It generates static HTML for dynamic pages.

// Example of setting up Angular Universal
ng add @nguniversal/express-engine

15. How do you handle error handling in Angular 8?

Error handling in Angular 8 is typically done using RxJS operators like catchError or by using Angular’s built-in error handling mechanism for HTTP requests.

// Example of using catchError for HTTP requests
import { catchError } from 'rxjs/operators';

this.http.get('/api/data').pipe(
  catchError((error) => {
    console.error('Error:', error);
    return [];
  })
);

16. What is ngFor in Angular 8?

ngFor is a structural directive in Angular that allows you to loop over a collection of data and render a template once for each item in the collection.

<!-- Example of using ngFor in Angular template -->
<ul>
  <li *ngFor="let item of items">{{ item }}</li>
</ul>

17. What are Angular services?

Angular services are singleton objects that can be injected into components, directives, or other services. They provide a way to share data and functionality across different parts of an application.

// Example of creating a service in Angular
@Injectable({
  providedIn: 'root',
})
export class DataService {
  // Service logic here
}

18. What is Angular Routing in Angular 8?

Angular Routing is a mechanism that allows users to navigate between different components in an Angular application without having to perform a full page refresh.

// Example of setting up routes in Angular
const routes: Routes = [
  { path: 'home', component: HomeComponent },
  { path: 'about', component: AboutComponent }
];

19. Explain the purpose of ViewChild in Angular 8.

ViewChild is a decorator in Angular used to get the first element that matches a given directive, component, or template variable from the view DOM.

// Example of using ViewChild in Angular component
@ViewChild('myElement', { static: true }) myElement: ElementRef;

20. What is Angular Material in Angular 8?

Angular Material is a UI component library for Angular that provides a set of high-quality UI components like buttons, cards, forms, and more, following the Material Design guidelines.

# Example of installing Angular Material
ng add @angular/material

21. How do you implement two-way data binding in Angular 8?

Two-way data binding in Angular 8 is achieved using the ngModel directive. It binds a model property to an input element, allowing changes in the input to update the model and vice versa.

<!-- Example of two-way data binding in Angular template -->
<input [(ngModel)]="name">

22. Explain the concept of change detection in Angular 8.

Change detection in Angular 8 is the process of determining if there are changes in the application’s state and updating the view to reflect those changes. Angular uses Zone.js for efficient change detection.

// Example of manually triggering change detection in Angular
import { ChangeDetectorRef } from '@angular/core';

constructor(private cdr: ChangeDetectorRef) {}

updateData() {
  // Update data
  this.cdr.detectChanges();
}

23. What is Angular Ivy Renderer in Angular 8?

Angular Ivy Renderer is a part of the Ivy rendering engine introduced in Angular 8. It is responsible for rendering components and templates efficiently.

// Example of enabling Ivy rendering engine in angular.json
"angularCompilerOptions": {
  "enableIvy": true
}

24. What is Angular Directives in Angular 8?

Angular directives are instructions in the DOM that tell Angular how to transform the DOM elements. There are three types of directives: component directives, structural directives, and attribute directives.

// Example of a custom attribute directive in Angular
@Directive({
  selector: '[appHighlight]'
})
export class HighlightDirective {
  // Directive logic here
}

25. Explain NgZone in Angular 8.

NgZone is a service in Angular that provides a zone where Angular can perform change detection. It’s used to explicitly run tasks outside or inside Angular’s zone.

// Example of using NgZone in Angular component
import { NgZone } from '@angular/core';

constructor(private zone: NgZone) {}

runOutsideAngularZone() {
  this.zone.runOutsideAngular(() => {
    // Code to run outside Angular's zone
  });
}

26. What is Angular HttpClient in Angular 8?

Angular HttpClient is a module in Angular 8 that simplifies making HTTP requests. It provides methods for all HTTP request types like GET, POST, PUT, DELETE, etc.

// Example of making an HTTP GET request in Angular
import { HttpClient } from '@angular/common/http';

constructor(private http: HttpClient) {}

getData() {
  return this.http.get('/api/data');
}

27. Explain the purpose of ActivatedRoute in Angular 8.

ActivatedRoute is a service in Angular 8 that provides information about the currently activated route. It contains parameters, data, and the URL segment of the current route.

// Example of using ActivatedRoute in Angular component
import { ActivatedRoute } from '@angular/router';

constructor(private route: ActivatedRoute) {
  this.route.params.subscribe(params => {
    console.log(params.id);
  });
}

28. What is Angular NgClass in Angular 8?

NgClass is a built-in directive in Angular that allows you to dynamically set CSS classes on an HTML element based on certain conditions.

<!-- Example of using NgClass in Angular template -->
<div [ngClass]="{ 'active': isActive, 'disabled': isDisabled }">Content</div>

29. Explain Angular NgIfElse in Angular 8.

NgIfElse is a structural directive in Angular that allows you to conditionally render different templates based on a condition.

<!-- Example of using NgIfElse in Angular template -->
<div *ngIf="condition; else elseBlock">Content</div>
<ng-template #elseBlock>Alternate Content</ng-template>

30. What is Angular TestBed in Angular 8?

Angular TestBed is a utility in Angular 8 for configuring and creating an Angular testing module. It provides methods for compiling components and creating instances for testing.

// Example of using TestBed in Angular testing
beforeEach(() => {
  TestBed.configureTestingModule({
    declarations: [MyComponent],
    providers: [MyService]
  });

  fixture = TestBed.createComponent(MyComponent);
  component = fixture.componentInstance;
});

31. What is Angular Pipes in Angular 8?

Angular Pipes are a way to transform and format data in an Angular template. There are built-in pipes for common tasks like currency formatting, date formatting, and more.

<!-- Example of using a built-in pipe in Angular template -->
{{ today | date:'shortDate' }}

32. Explain Angular Interceptors in Angular 8.

Angular Interceptors are a way to intercept HTTP requests or responses before they are sent or received. They are used for tasks like adding headers, handling errors, etc.

// Example of creating an HTTP interceptor in Angular
@Injectable()
export class MyInterceptor implements HttpInterceptor {
  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    // Interception logic here
    return next.handle(req);
  }
}

33. What is Angular Forms in Angular 8?

Angular Forms are a way to handle user input in an Angular application. There are two types of forms: template-driven forms and reactive forms.

<!-- Example of a template-driven form in Angular template -->
<form #myForm="ngForm" (ngSubmit)="onSubmit()">
  <input [(ngModel)]="name" name="name" required>
  <button type="submit">Submit</button>
</form>

34. Explain Angular RxJS in Angular 8.

Angular RxJS (Reactive Extensions for JavaScript) is a library for reactive programming using Observables. It’s used extensively in Angular for handling asynchronous operations.

// Example of using RxJS in Angular service
import { Observable } from 'rxjs';
import { HttpClient } from '@angular/common/http';

getData(): Observable<any> {
  return this.http.get('/api/data');
}

35. What is Angular NgRx in Angular 8?

NgRx is a set of reactive extensions for Angular, providing a state management solution based on Redux principles. It’s used for managing the state of an Angular application.

# Example of installing NgRx
ng add @ngrx/store

36. Explain Angular Dependency Injection in Angular 8.

Angular Dependency Injection is a design pattern used to manage dependencies between different parts of an Angular application. It allows components and services to receive dependencies rather than creating them.

// Example of injecting a service in Angular component
constructor(private dataService: DataService) {}

37. What is Angular NgZone in Angular 8?

Angular NgZone is a service that provides a zone where Angular can perform change detection. It’s used to explicitly run tasks outside or inside Angular’s zone.

// Example of using NgZone in Angular component
import { NgZone } from '@angular/core';

constructor(private zone: NgZone) {}

runOutsideAngularZone() {
  this.zone.runOutsideAngular(() => {
    // Code to run outside Angular's zone
  });
}

38. Explain Angular Services in Angular 8.

Angular services are singleton objects that can be injected into components, directives, or other services. They provide a way to share data and functionality across different parts of an application.

// Example of creating a service in Angular
@Injectable({
  providedIn: 'root',
})
export class DataService {
  // Service logic here
}

39. What is Angular NgClass in Angular 8?

Angular NgClass is a built-in directive that allows you to dynamically set CSS classes on an HTML element based on certain conditions.

<!-- Example of using NgClass in Angular template -->
<div [ngClass]="{ 'active': isActive, 'disabled': isDisabled }">Content</div>

40. Explain Angular NgFor in Angular 8.

Angular NgFor is a structural directive that allows you to loop over a collection of data and render a template once for each item in the collection.

<!-- Example of using NgFor in Angular template -->
<ul>
  <li *ngFor="let item of items">{{ item }}</li>
</ul>

41. What is Angular NgIfElse in Angular 8?

Angular NgIfElse is a structural directive that allows you to conditionally render different templates based on a condition.

<!-- Example of using NgIfElse in Angular template -->
<div *ngIf="condition; else elseBlock">Content</div>
<ng-template #elseBlock>Alternate Content</ng-template>

42. What is Angular NgSwitch in Angular 8?

Angular NgSwitch is a structural directive that allows you to conditionally switch among a set of templates based on the evaluated value of an expression.

<!-- Example of using NgSwitch in Angular template -->
<div [ngSwitch]="value">
  <div *ngSwitchCase="'A'">Value is A</div>
  <div *ngSwitchCase="'B'">Value is B</div>
  <div *ngSwitchDefault>Value is something else</div>
</div>

43. What is Angular ng-container in Angular 8?

Angular ng-container is a grouping element that doesn’t interfere with styles or layout. It’s often used with structural directives when you want to apply the directive to multiple elements.

<!-- Example of using ng-container in Angular template -->
<ng-container *ngIf="condition">
  <div>Content 1</div>
  <div>Content 2</div>
</ng-container>

44. Explain Angular ViewChild in Angular 8.

ViewChild is a decorator in Angular used to get the first element that matches a given directive, component, or template variable from the view DOM.

// Example of using ViewChild in Angular component
@ViewChild('myElement', { static: true }) myElement: ElementRef;

45. What is Angular ng-content in Angular 8?

Angular ng-content is a way to pass content into a component from outside. It allows you to create reusable components with customizable content.

<!-- Example of using ng-content in Angular component -->
<app-modal>
  <h1>Custom Header</h1>
  <p>Modal Content</p>
</app-modal>

46. Explain Angular ng-template in Angular 8.

Angular ng-template is a way to define a template that can be used within the component. It’s often used with structural directives like ngIf, ngFor, etc.

<!-- Example of using ng-template in Angular component -->
<ng-template #myTemplate>
  <div>Template Content</div>
</ng-template>

47. What is Angular ngOnChanges in Angular 8?

ngOnChanges is a lifecycle hook in Angular that is called when one or more data-bound input properties of a directive or a component change.

// Example of using ngOnChanges in Angular component
ngOnChanges(changes: SimpleChanges) {
  // Logic for handling changes
}

48. Explain Angular ngDoCheck in Angular 8.

ngDoCheck is a lifecycle hook in Angular that is called during every change detection run, allowing you to implement your own change detection logic.

// Example of using ngDoCheck in Angular component
ngDoCheck() {
  // Custom change detection logic
}

49. What is Angular ngOnDestroy in Angular 8?

ngOnDestroy is a lifecycle hook in Angular that is called just before the directive or component is destroyed.

// Example of using ngOnDestroy in Angular component
ngOnDestroy() {
  // Cleanup logic here
}

50. Explain Angular ContentChild in Angular 8.

Angular ContentChild is a decorator used to get the first element or the directive matching the selector from the content DOM.

// Example of using ContentChild in Angular component
@ContentChild('myElement', { static: true }) myElement: ElementRef;

51. What is Angular ContentChildren in Angular 8?

Angular ContentChildren is a decorator used to get a QueryList of elements or directives from the content DOM.

// Example of using ContentChildren in Angular component
@ContentChildren('myElement') myElements: QueryList<ElementRef>;

52. Explain Angular ElementRef in Angular 8.

Angular ElementRef is a service that grants direct access to the DOM element through its nativeElement property.

// Example of using ElementRef in Angular component
import { ElementRef } from '@angular/core';

constructor(private elRef: ElementRef) {
  this.elRef.nativeElement.style.backgroundColor = 'yellow';
}

53. What is Angular Renderer2 in Angular 8?

Angular Renderer2 is an abstraction for manipulating the DOM. It’s used instead of directly accessing the DOM, which can improve performance and security.

// Example of using Renderer2 in Angular component
import { Renderer2 } from '@angular/core';

constructor(private renderer: Renderer2) {
  const element = this.renderer.createElement('div');
  this.renderer.appendChild(parentElement, element);
}

54. Explain Angular ChangeDetectorRef in Angular 8.

Angular ChangeDetectorRef is a service that provides a way to manually trigger change detection in a component.

// Example of using ChangeDetectorRef in Angular component
import { ChangeDetectorRef } from '@angular/core';

constructor(private cdr: ChangeDetectorRef) {}

updateData() {
  // Update data
  this.cdr.detectChanges();
}

55. What is Angular ViewContainerRef in Angular 8?

Angular ViewContainerRef is a class that represents a container where one or more views can be attached.

// Example of using ViewContainerRef in Angular component
import { ViewContainerRef } from '@angular/core';

constructor(private viewContainerRef: ViewContainerRef) {
  const elementRef = this.viewContainerRef.element.nativeElement;
}

56. Explain Angular TemplateRef in Angular 8.

Angular TemplateRef is a class that represents an embedded template that can be used to instantiate views.

// Example of using TemplateRef in Angular component
import { TemplateRef } from '@angular/core';

constructor(private templateRef: TemplateRef<any>) {
  const viewRef = this.templateRef.createEmbeddedView(null);
}

57. What is Angular ng-container in Angular 8?

Angular ng-container is a grouping element that doesn’t interfere with styles or layout. It’s often used with structural directives when you want to apply the directive to multiple elements.

<!-- Example of using ng-container in Angular template -->
<ng-container *ngIf="condition">
  <div>Content 1</div>
  <div>Content 2</div>
</ng-container>

58. Explain Angular ng-template in Angular 8.

Angular ng-template is a way to define a template that can be used within the component. It’s often used with structural directives like ngIf, ngFor, etc.

<!-- Example of using ng-template in Angular component -->
<ng-template #myTemplate>
  <div>Template Content</div>
</ng-template>

59. What is Angular ng-template with ngIf in Angular 8?

Angular ng-template with ngIf is a way to conditionally render content without adding unnecessary elements to the DOM.

<!-- Example of using ng-template with ngIf in Angular template -->
<ng-container *ngIf="condition; then trueTemplate else falseTemplate"></ng-container>

<ng-template #trueTemplate>Content if condition is true</ng-template>
<ng-template #falseTemplate>Content if condition is false</ng-template>

60. Explain Angular ng-container with ngTemplateOutlet in Angular 8.

Angular ng-container with ngTemplateOutlet is a way to dynamically render templates based on conditions.

<!-- Example of using ng-container with ngTemplateOutlet in Angular template -->
<ng-container *ngTemplateOutlet="condition ? trueTemplate : falseTemplate"></ng-container>

<ng-template #trueTemplate>Content if condition is true</ng-template>
<ng-template #falseTemplate>Content if condition is false</ng-template>

61. What is Angular CDK in Angular 8?

Angular CDK (Component Dev Kit) is a set of tools and building blocks for building complex UI components in Angular. It provides APIs for common interaction patterns.

# Example of installing Angular CDK
ng add @angular/cdk

62. Explain Angular Material in Angular 8.

Angular Material is a UI component library for Angular applications. It provides a set of high-quality UI components like buttons, inputs, dialogs, etc.

# Example of installing Angular Material
ng add @angular/material

63. What is Angular ngRx in Angular 8?

NgRx is a set of reactive extensions for Angular, providing a state management solution based on Redux principles. It’s used for managing the state of an Angular application.

# Example of installing NgRx
ng add @ngrx/store

64. Explain Angular Animations in Angular 8.

Angular Animations is a module in Angular that allows you to animate elements in your application. It provides a way to create complex animations.

// Example of using animations in Angular component
@Component({
  animations: [
    trigger('myAnimation', [
      state('start', style({ opacity: 1 })),
      transition('void => *', animate('500ms'))
    ])
  ]
})

65. What is Angular Universal in Angular 8?

Angular Universal is a technology in Angular that allows you to run your Angular applications on the server, enabling server-side rendering for better SEO and performance.

# Example of adding Angular Universal to an Angular app
ng add @nguniversal/express-engine

66. What is Angular Lazy Loading in Angular 8?

Angular Lazy Loading is a technique that allows you to load modules only when they are needed. This improves the initial loading time of your application.

// Example of lazy loading a module in Angular routing
const routes: Routes = [
  { path: 'lazy', loadChildren: () => import('./lazy/lazy.module').then(m => m.LazyModule) }
];

67. Explain Angular Ahead-of-Time (AOT) Compilation in Angular 8.

Angular Ahead-of-Time (AOT) Compilation is a process of pre-compiling Angular code during the build phase. This improves the performance of the application at runtime.

# Example of building with AOT in Angular
ng build --aot

68. What is Angular ng-container with ngTemplateOutlet in Angular 8?

Angular ng-container with ngTemplateOutlet is a way to dynamically render templates based on conditions.

<!-- Example of using ng-container with ngTemplateOutlet in Angular template -->
<ng-container *ngTemplateOutlet="condition ? trueTemplate : falseTemplate"></ng-container>

<ng-template #trueTemplate>Content if condition is true</ng-template>
<ng-template #falseTemplate>Content if condition is false</ng-template>

69. Explain Angular CDK (Component Dev Kit) in Angular 8.

Angular CDK is a set of tools and building blocks for building complex UI components in Angular. It provides APIs for common interaction patterns.

# Example of installing Angular CDK
ng add @angular/cdk

70. What is Angular Material in Angular 8?

Angular Material is a UI component library for Angular applications. It provides a set of high-quality UI components like buttons, inputs, dialogs, etc.

# Example of installing Angular Material
ng add @angular/material

71. Explain Angular Reactive Forms in Angular 8.

Angular Reactive Forms are a way to manage form state and validation in Angular applications using RxJS.

// Example of creating a form in Angular component
import { FormBuilder, FormGroup, Validators } from '@angular/forms';

constructor(private fb: FormBuilder) {
  this.myForm = this.fb.group({
    name: ['', Validators.required],
    email: ['', [Validators.required, Validators.email]],
  });
}

72. What is Angular Dynamic Components in Angular 8?

Angular Dynamic Components allow you to create and render components dynamically at runtime.

// Example of creating and rendering a dynamic component in Angular
const componentFactory = this.componentFactoryResolver.resolveComponentFactory(DynamicComponent);
this.containerRef.createComponent(componentFactory);

73. Explain Angular ViewChildren in Angular 8.

Angular ViewChildren is a decorator used to get a QueryList of elements or directives from the view DOM.

// Example of using ViewChildren in Angular component
@ViewChildren('myElement') myElements: QueryList<ElementRef>;

74. What is Angular ElementRef in Angular 8?

Angular ElementRef is a service that grants direct access to the DOM element through its nativeElement property.

// Example of using ElementRef in Angular component
import { ElementRef } from '@angular/core';

constructor(private elRef: ElementRef) {
  this.elRef.nativeElement.style.backgroundColor = 'yellow';
}

75. Explain Angular Renderer2 in Angular 8.

Angular Renderer2 is an abstraction for manipulating the DOM. It’s used instead of directly accessing the DOM, which can improve performance and security.

// Example of using Renderer2 in Angular component
import { Renderer2 } from '@angular/core';

constructor(private renderer: Renderer2) {
  const element = this.renderer.createElement('div');
  this.renderer.appendChild(parentElement, element);
}

76. What is Angular ChangeDetectorRef in Angular 8?

Angular ChangeDetectorRef is a service that provides a way to manually trigger change detection in a component.

// Example of using ChangeDetectorRef in Angular component
import { ChangeDetectorRef } from '@angular/core';

constructor(private cdr: ChangeDetectorRef) {}

updateData() {
  // Update data
  this.cdr.detectChanges();
}

77. Explain Angular ContentChild in Angular 8.

Angular ContentChild is a decorator used to get the first element or the directive matching the selector from the content DOM.

// Example of using ContentChild in Angular component
@ContentChild('myElement', { static: true }) myElement: ElementRef;

78. What is Angular ContentChildren in Angular 8?

Angular ContentChildren is a decorator used to get a QueryList of elements or directives from the content DOM.

// Example of using ContentChildren in Angular component
@ContentChildren('myElement') myElements: QueryList<ElementRef>;

79. Explain Angular ng-template with ngIf in Angular 8.

Angular ng-template with ngIf is a way to conditionally render content without adding unnecessary elements to the DOM.

<!-- Example of using ng-template with ngIf in Angular template -->
<ng-container *ngIf="condition; then trueTemplate else falseTemplate"></ng-container>

<ng-template #trueTemplate>Content if condition is true</ng-template>
<ng-template #falseTemplate>Content if condition is false</ng-template>

80. What is Angular ng-template with ngFor in Angular 8?

Angular ng-template with ngFor is a way to loop over a collection of data and render a template once for each item in the collection.

<!-- Example of using ng-template with ngFor in Angular template -->
<ul>
  <li *ngFor="let item of items; let i = index">{{ item }}</li>
</ul>

81. Explain Angular ng-template with ngSwitch in Angular 8.

Angular ng-template with ngSwitch is a way to conditionally switch among a set of templates based on the evaluated value of an expression.

<!-- Example of using ng-template with ngSwitch in Angular template -->
<div [ngSwitch]="value">
  <div *ngSwitchCase="'A'">Value is A</div>
  <div *ngSwitchCase="'B'">Value is B</div>
  <div *ngSwitchDefault>Value is something else</div>
</div>

82. What is Angular ng-template with ngSwitchCase in Angular 8?

Angular ng-template with ngSwitchCase is a way to conditionally switch among a set of templates based on the evaluated value of an expression.

<!-- Example of using ng-template with ngSwitchCase in Angular template -->
<div [ngSwitch]="value">
  <ng-template ngSwitchCase="'A'">Value is A</ng-template>
  <ng-template ngSwitchCase="'B'">Value is B</ng-template>
  <ng-template ngSwitchDefault>Value is something else</ng-template>
</div>

83. Explain Angular ng-container with ngSwitchCase in Angular 8.

Angular ng-container with ngSwitchCase is a way to conditionally render content without adding unnecessary elements to the DOM.

<!-- Example of using ng-container with ngSwitchCase in Angular template -->
<div [ngSwitch]="value">
  <ng-container *ngSwitchCase="'A'">Value is A</ng-container>
  <ng-container *ngSwitchCase="'B'">Value is B</ng-container>
  <ng-container *ngSwitchDefault>Value is something else</ng-container>
</div>

84. What is Angular ng-container with ngSwitchDefault in Angular 8?

Angular ng-container with ngSwitchDefault is a way to conditionally render content without adding unnecessary elements to the DOM.

<!-- Example of using ng-container with ngSwitchDefault in Angular template -->
<div [ngSwitch]="value">
  <ng-container *ngSwitchCase="'A'">Value is A</ng-container>
  <ng-container *ngSwitchCase="'B'">Value is B</ng-container>
  <ng-container *ngSwitchDefault>Value is something else</ng-container>
</div>

85. Explain Angular ng-container with ngSwitchWhen in Angular 8.

Angular ng-container with ngSwitchWhen is a way to conditionally render content without adding unnecessary elements to the DOM.

<!-- Example of using ng-container with ngSwitchWhen in Angular template -->
<div [ngSwitch]="value">
  <ng-container *ngSwitchCase="'A'">Value is A</ng-container>
  <ng-container *ngSwitchCase="'B'">Value is B</ng-container>
  <ng-container *ngSwitchWhen="'C'">Value is C</ng-container>
</div>

86. What is Angular ng-container with ngSwitchWhen in Angular 8?

Angular ng-container with ngSwitchWhen is a way to conditionally render content without adding unnecessary elements to the DOM.

<!-- Example of using ng-container with ngSwitchWhen in Angular template -->
<div [ngSwitch]="value">
  <ng-container *ngSwitchCase="'A'">Value is A</ng-container>
  <ng-container *ngSwitchCase="'B'">Value is B</ng-container>
  <ng-container *ngSwitchWhen="'C'">Value is C</ng-container>
</div>

87. Explain Angular ng-container with ngSwitchDefault in Angular 8.

Angular ng-container with ngSwitchDefault is a way to conditionally render content without adding unnecessary elements to the DOM.

<!-- Example of using ng-container with ngSwitchDefault in Angular template -->
<div [ngSwitch]="value">
  <ng-container *ngSwitchCase="'A'">Value is A</ng-container>
  <ng-container *ngSwitchCase="'B'">Value is B</ng-container>
  <ng-container *ngSwitchDefault>Value is something else</ng-container>
</div>

88. What is Angular ng-container with ngSwitchWhen in Angular 8?

Angular ng-container with ngSwitchWhen is a way to conditionally render content without adding unnecessary elements to the DOM.

<!-- Example of using ng-container with ngSwitchWhen in Angular template -->
<div [ngSwitch]="value">
  <ng-container *ngSwitchCase="'A'">Value is A</ng-container>
  <ng-container *ngSwitchCase="'B'">Value is B</ng-container>
  <ng-container *ngSwitchWhen="'C'">Value is C</ng-container>
</div>

89. What is Angular ng-container with ngTemplateOutlet in Angular 8?

Angular ng-container with ngTemplateOutlet is a way to dynamically render templates based on conditions.

<!-- Example of using ng-container with ngTemplateOutlet in Angular template -->
<ng-container *ngTemplateOutlet="condition ? trueTemplate : falseTemplate"></ng-container>

<ng-template #trueTemplate>Content if condition is true</ng-template>
<ng-template #falseTemplate>Content if condition is false</ng-template>

90. Explain Angular ng-container with ngComponentOutlet in Angular 8.

Angular ng-container with ngComponentOutlet is a way to dynamically render components based on conditions.

<!-- Example of using ng-container with ngComponentOutlet in Angular template -->
<ng-container *ngComponentOutlet="condition ? TrueComponent : FalseComponent"></ng-container>

<!-- Component Definitions -->
<app-true *ngIf="condition"></app-true>
<app-false *ngIf="!condition"></app-false>

91. What is Angular ViewChild in Angular 8?

Angular ViewChild is a decorator used to get the first element or the directive matching the selector from the view DOM.

// Example of using ViewChild in Angular component
@ViewChild('myElement', { static: true }) myElement: ElementRef;

92. Explain Angular ViewChildren in Angular 8.

Angular ViewChildren is a decorator used to get a QueryList of elements or directives from the view DOM.

// Example of using ViewChildren in Angular component
@ViewChildren('myElement') myElements: QueryList<ElementRef>;

93. What is Angular ContentChild in Angular 8?

Angular ContentChild is a decorator used to get the first element or the directive matching the selector from the content DOM.

// Example of using ContentChild in Angular component
@ContentChild('myElement', { static: true }) myElement: ElementRef;

94. Explain Angular ContentChildren in Angular 8.

Angular ContentChildren is a decorator used to get a QueryList of elements or directives from the content DOM.

// Example of using ContentChildren in Angular component
@ContentChildren('myElement') myElements: QueryList<ElementRef>;

95. What is Angular ElementRef in Angular 8?

Angular ElementRef is a service that grants direct access to the DOM element through its nativeElement property.

// Example of using ElementRef in Angular component
import { ElementRef } from '@angular/core';

constructor(private elRef: ElementRef) {
  this.elRef.nativeElement.style.backgroundColor = 'yellow';
}

96. Explain Angular Renderer2 in Angular 8.

Angular Renderer2 is an abstraction for manipulating the DOM. It’s used instead of directly accessing the DOM, which can improve performance and security.

// Example of using Renderer2 in Angular component
import { Renderer2 } from '@angular/core';

constructor(private renderer: Renderer2) {
  const element = this.renderer.createElement('div');
  this.renderer.appendChild(parentElement, element);
}

97. What is Angular ChangeDetectorRef in Angular 8?

Angular ChangeDetectorRef is a service that provides a way to manually trigger change detection in a component.

// Example of using ChangeDetectorRef in Angular component
import { ChangeDetectorRef } from '@angular/core';

constructor(private cdr: ChangeDetectorRef) {}

updateData() {
  // Update data
  this.cdr.detectChanges();
}

98. What is Angular ng-template with ngIf in Angular 8?

Angular ng-template with ngIf is a way to conditionally render content without adding unnecessary elements to the DOM.

<!-- Example of using ng-template with ngIf in Angular template -->
<ng-container *ngIf="condition; then trueTemplate else falseTemplate"></ng-container>

<ng-template #trueTemplate>Content if condition is true</ng-template>
<ng-template #falseTemplate>Content if condition is false</ng-template>

99. What is Angular ng-template with ngFor in Angular 8?

Angular ng-template with ngFor is a way to loop over a collection of data and render a template once for each item in the collection.

<!-- Example of using ng-template with ngFor in Angular template -->
<ul>
  <li *ngFor="let item of items; let i = index">{{ item }}</li>
</ul>

100. Explain Angular ng-template with ngSwitch in Angular 8.

Angular ng-template with ngSwitch is a way to conditionally switch among a set of templates based on the evaluated value of an expression.

<!-- Example of using ng-template with ngSwitch in Angular template -->
<div [ngSwitch]="value">
  <div *ngSwitchCase="'A'">Value is A</div>
  <div *ngSwitchCase="'B'">Value is B</div>
  <div *ngSwitchDefault>Value is something else</div>
</div>