Angular 4 Interview Questions and Answers

Prepare for your Angular 4 interview with our essential Questions and Answers guide! Whether you’re just starting or a seasoned developer, this resource is your key to confidently handling interviews. Explore crucial concepts, sharpen your skills, and approach your Angular 4 interview with confidence. From basics to common challenges, we’ve got you covered. Boost your understanding, polish your abilities, and walk into your interview well-prepared. Mastering Angular 4 is crucial for staying ahead in web development. Ace your interview, highlighting your expertise in Angular 4, and consider our AngularJS Training in Chennai for comprehensive learning and career advancement.

What are the components of Angular?

Angular incorporates essential building blocks within its framework:

  • Modules: Efficiently organize the application.
  • Components: Construct various segments within the app.
  • Templates: Define how data is presented.
  • Directives: Enhance HTML functionality with additional features.
  • Services: Provide reusable elements for different app sections.
  • Dependency Injection (DI): Enhance efficiency and modularity.
  • Data Binding: Establish a link between templates and components.
  • Metadata: Supply extra information to elevate app features.

Collectively, these components empower developers to create dynamic and robust web applications.

What is TypeScript in Angular 4?

In Angular 4, TypeScript is the main language for creating web applications. TypeScript, a superset of JavaScript, adds features like static typing and classes to enhance development. Angular 4 utilizes TypeScript’s benefits for building scalable and organized code, improving tooling support and error detection. The TypeScript code is later converted to standard JavaScript for browser compatibility.

What are the different types of binding options in Angular 4?

Angular 4 provides various ways to establish dynamic connections between components:

  • Interpolation ({{ }}): Displays component properties dynamically in the view.
  • Property Binding ([ ]): Sets an element’s property using a corresponding component property.
  • Event Binding (( )): Responds to user-triggered events and executes related component methods.
  • Two-Way Binding ([(ngModel)]): Integrates property and event binding for synchronized data between the component and view.

These binding options enhance Angular 4 applications, ensuring adaptability and responsiveness.

How does a pure pipe differ from an impure pipe?

In Angular, pipes transform template data. Pure pipes update only when input values change, ensuring performance by maintaining immutability ({{ data | purePipe }}). In contrast, impure pipes allow more frequent updates, even with every change detection cycle ({{ data | impurePipe }}). The choice depends on the specific need: pure pipes for optimized performance based on input changes and impure pipes for more frequent updates.

What is Angular Router and use of this?

Angular Router is a module that streamlines navigation in single-page applications. It dynamically updates the URL and renders components based on routes, allowing smooth transitions between views without reloading the entire page. Supporting deep linking, route parameters, and guards, it enhances user experience, accessibility, and overall application structure.

What is the difference between Directives and Components in Angular 4?

DefinitionCore elements for self-contained UI featuresInstructions for altering DOM structure or behavior
CompositionTemplates, logic (Typescript class), and stylesTypically a Typescript class with @Directive decorator, may have associated templates
MetadataDeclared using @ComponentDeclared using @Directive
UseCreate dynamic views, encapsulate behavior, and manage application stateExtend HTML elements’ behavior, apply dynamic styles, or manipulate the DOM in response to user actions

What is Unit Testing in Angular 4?

Angular 4 unit testing is about verifying the behavior of individual code units, such as components and services. It employs testing frameworks like Jasmine, utilizes TestBed for creating a testing environment, organizes tests into suites, and uses assertions to check expected outcomes. The practice aids in early bug detection, enhances code maintainability, and supports seamless integration.

What do you understand about Modules in Angular 4?

In Angular 4, modules, defined with @NgModule, are crucial for structuring applications. They organize related components, directives, pipes, and services, promoting modularity and efficient code management. Modules can have dependencies, enable lazy loading for better performance, and are pivotal in building scalable applications. The root module, where the primary component is typically bootstrapped, serves as the starting point for an Angular application.

What is Angular 4?

Angular 4, a JavaScript framework by Google, facilitates the creation of dynamic single-page web applications. Introduced in March 2017, it advances upon Angular 2 with a focus on enhanced performance and simplified development. Utilizing TypeScript, Angular 4 introduces crucial concepts like components, modules, services, and directives, elevating the development of modern and easily maintainable web applications.

How to handle HTTP error response in Angular 4?

To handle HTTP errors in Angular 4, utilize the Http service and Observables. Import required modules, handle errors in HTTP requests using the catch operator, and subscribe to the Observable in the component. Customize the handleError method for specific error-handling needs, ensuring effective management of error responses for a more robust Angular application.

What is the use of base href tag?

The <base href> tag in HTML, placed within the <head> section, sets the base URL for all relative URLs in the document. In Angular applications, it holds significance by establishing the base URL for the application’s routes. This is essential for accurate navigation and resolution of relative URLs, ensuring proper functionality of routing in Angular single-page applications (SPAs).

How does Angular 4 use services?

In Angular 4, services play a vital role in facilitating code organization, sharing functionality across components, and managing application state. They promote modularity by encapsulating reusable logic, such as data retrieval or business operations. Services are a key component of Angular’s dependency injection system, ensuring efficient communication between components and enhancing code maintainability and scalability.

How can routing be implemented in Angular 4?

To implement routing in Angular 4, follow these steps:

  • Set Up Routes: Define routes in the app.module.ts file using the RouterModule.forRoot() method.
  • Create Components: Develop components for each route.
  • Define Route Links: In the template, use the routerLink directive to create links for navigation.
  • Set Up Router Outlet: Add a <router-outlet> element in the template to display routed components.
  • Navigate Between Routes: Utilize the Router service to navigate between routes programmatically.

// app.module.ts

import { RouterModule, Routes } from ‘@angular/router’;

const routes: Routes = [

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

  { path: ‘about’, component: AboutComponent },

  // Add more routes as needed



  imports: [RouterModule.forRoot(routes)],

  exports: [RouterModule],


export class AppRoutingModule {}

// app.component.html


  <a routerLink=”/home”>Home</a>

  <a routerLink=”/about”>About</a>



What are the characteristics of Angular 4?

Angular 4 introduced significant features and enhancements to boost performance and streamline development:

  • Enhanced View Engine: Angular 4 introduced a more streamlined view engine, reducing generated code and improving runtime performance.
  • Dedicated Animation Package: Simplifies the addition of animations to components.
  • Improved ngIf and ngFor Directives: Streamlined handling of *ngIf and *ngFor for better performance and reduced code size.
  • ngIf with Else Statement: Added the ability to use the else statement with *ngIf for more precise template control.
  • ngModelChange Event: Introduced the ngModelChange event, enhancing flexibility in two-way data binding.
  • HttpClientModule Replaces HttpModule: Improved features and usability with the replacement of HttpModule by HttpClientModule.
  • ParamMap in Router: Router introduced the ParamMap interface for convenient access to route parameters.
  • TypeScript 2.1 and 2.2 Support: Angular 4 supported TypeScript 2.1 and 2.2, allowing developers to leverage the latest TypeScript features.

How should events be effectively managed in Angular 4?

The recommended method for event handling in Angular 4 involves event binding. This technique enables responses to user actions, such as button clicks or input changes, by binding component methods to specific events in the template. Event binding promotes code organization and maintainability, aligning with Angular’s declarative approach to constructing interactive web applications.

What does deep linking mean in Angular 4?

In Angular 4, deep linking allows direct access to specific pages or components within a single-page application (SPA) through URLs. By configuring routes, users can share or bookmark deep-linked URLs, and Angular’s router interprets these URLs to navigate to the corresponding component. This enables direct access to specific views in the application without requiring a complete page reload.

How is eager loading defined in Angular 4?

In Angular 4, eager loading entails loading modules immediately upon the application startup. When a module is eagerly loaded, its components, services, and resources are initialized right away. This differs from lazy loading, where modules are fetched on-demand. Eager loading is advantageous for modules critical to the core functionality of the application, ensuring essential components are readily available from the beginning.

What role does a guard play in Angular 4?

In Angular 4, guards regulate route navigation by imposing conditions before allowing access. They act as protective measures for routes, with types like CanActivate, CanActivateChild, CanDeactivate, and CanLoad. These guards enable developers to introduce logic based on conditions such as user authentication, ensuring a secure and controlled navigation flow in an Angular application.

What is the role of providers in Angular 4?

Angular 4 providers instruct the Dependency Injection system on service instantiation. They dictate how services are created and injected across the application, with various types:

  • Class Providers: Use a class as a provider.
  • Value Providers: Supply a simple value, like a constant.
  • Factory Providers: Utilize a factory function to create the service.
  • Existing Providers: Reuse an existing service instance.

These providers, specified in the providers array of Angular modules or components, articulate the essential dependencies for the application.

How can an external js file be included in Angular 4?

To include external JavaScript files in Angular 4, follow these steps:

  • Open the “angular.json” configuration file.
  • Find the “scripts” array in the relevant section, either “build” or “test.”
  • Insert the path to your external JavaScript file within the “scripts” array.

“scripts”: [



  • Save the modifications.

Angular CLI will automatically include the specified external JavaScript file during the build or when running your Angular application. Replace “path/to/external-file.js” with the accurate file path and restart your Angular development server for the changes to take effect.


In conclusion, mastering Angular 4 is essential for web development innovation. Our guide readies you for interviews, whether you’re a beginner or seasoned. Boost your skills confidently and explore our AngularJS Training in Chennai for career growth. It’s more than preparation; it’s an investment in your professional journey. Enter interviews with assurance, showcase your Angular 4 expertise, and unlock opportunities in the dynamic realm of web development.