Latest 100 Angular Interview Question

Introduction

Get ready to ace your Angular interview with this comprehensive list of commonly asked questions and their expertly crafted answers.

Basic Questions

1. What is Angular?

Angular is a popular open-source web application framework developed by Google. It allows developers to build dynamic, single-page applications (SPAs) and is based on TypeScript, a superset of JavaScript. Angular provides a comprehensive set of tools and features for building scalable and maintainable applications, including data binding, dependency injection, component-based architecture, and declarative templates.

2. Why were client-side frameworks like Angular introduced?

Client-side frameworks like Angular were introduced to address the complexities of developing modern web applications. Traditional web applications relied on server-side rendering, where most of the processing was done on the server and the resulting HTML was sent to the client. With the rise of web applications that require rich interactivity and real-time updates, the need for more powerful client-side frameworks emerged. These frameworks enable developers to build complex user interfaces, handle data binding, and manage application state on the client side, providing a more responsive and interactive user experience.

3. What are some of the advantages of Angular over other frameworks?

Angular offers several advantages over other frameworks:

• Full-featured framework: Angular provides a comprehensive solution for building web applications, including powerful features like data binding, dependency injection, routing, form handling, and testing utilities.
• TypeScript support: Angular is built with TypeScript, which adds static typing and advanced features to JavaScript, resulting in more reliable and maintainable code.
• Modular architecture: Angular encourages a modular approach through components and modules, making it easier to organize and maintain large-scale applications.
• Enhanced performance: Angular’s ahead-of-time (AOT) compilation and tree shaking techniques help optimize application performance by reducing bundle sizes and improving loading times.
• Rich ecosystem: Angular has a thriving ecosystem with a wide range of community-contributed libraries, tools, and resources, making it easier to extend and customize applications.
• Official support: Angular is backed by Google, providing regular updates, documentation, and community support.

4. What are templates in Angular?

In Angular, templates are used to define the structure and layout of the user interface for a component. They are written in HTML and can include Angular-specific syntax for data binding, event handling, and structural directives.

Here’s an example of an Angular component with a template:

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

@Component({
  selector: 'app-greeting',
  template: `
    <h1>Welcome, {{ name }}!</h1>
    <button (click)="sayHello()">Say Hello</button>
  `
})
export class GreetingComponent {
  name = 'John';

  sayHello() {
    alert(`Hello, ${this.name}!`);
  }
}

In this example, the template includes an interpolated expression {{ name }} to display the value of the name property, and an event binding (click)="sayHello()" to handle the button click event.

5. What are directives in Angular?

Directives in Angular are markers on a DOM element that instruct Angular to perform certain behaviors or transformations on that element or its children.

There are three types of directives in Angular:

1. Component Directives: These directives define reusable UI components with their own templates and logic.
2. Attribute Directives: These directives change the appearance or behavior of an element, component, or another directive.
3. Structural Directives: These directives manipulate the DOM layout by adding or removing elements.

Here’s an example of an attribute directive in Angular:

import { Directive, ElementRef, Renderer2 } from '@angular/core';

@Directive({
  selector: '[appHighlight]'
})
export class HighlightDirective {
  constructor(private el: ElementRef, private renderer: Renderer2) {
    this.renderer.setStyle(this.el.nativeElement, 'background-color', 'yellow');
  }
}

In this example, the HighlightDirective is an attribute directive that adds a yellow background color to the element it is applied to. The ElementRef is used to access the host element, and the Renderer2 is used to manipulate its style.

6. What’s the difference between an Angular Component and Module?

7. What is the minimum definition of a Component?

The minimum definition of an Angular component includes the following:

• Import the necessary dependencies from @angular/core:
• Component decorator for component configuration.
• OnInit interface (optional) for lifecycle hooks.
• Declare the component class and use the @Component decorator to configure it:
• Set the selector to define the component’s custom HTML tag.
• Set the template or templateUrl to define the component’s UI.
• Define any necessary properties and methods within the component class.

Here’s an example of a minimum component definition:

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

@Component({
  selector: 'app-greeting',
  template: '<h1>Hello, Angular!</h1>'
})
export class GreetingComponent implements OnInit {
  ngOnInit() {
    console.log('Component initialized');
  }
}

In this example, the GreetingComponent is defined with a custom selector 'app-greeting' and a template that renders an <h1> tag. The OnInit interface is implemented to use the ngOnInit lifecycle hook.

8. What is the purpose of the base href tag?

The <base href> tag is used in the HTML <head> section of an Angular application’s index.html file. It specifies the base URL for resolving relative URLs in the application.

Here’s an example: