What is HttpHeaders class in Angular?

The HttpHeaders class in Angular is a class that represents the header configuration options for an HTTP request. It is used to set and manage the headers that will be sent as part of an HTTP request made using the HttpClient module in Angular.

When making HTTP requests in Angular, it is often necessary to specify custom headers to be included in the request. This could include headers such as authentication tokens, content type, or other custom headers required by the server being accessed. The HttpHeaders class provides a convenient and type-safe way to manage these headers.

Here is a simple example of how the HttpHeaders class can be used in an Angular application:

    
      import { HttpHeaders, HttpClient } from '@angular/common/http';

      // Create an instance of the HttpHeaders class
      const headers = new HttpHeaders({
        'Content-Type': 'application/json',
        'Authorization': 'Bearer your-auth-token'
      });

      // Make an HTTP request using the HttpClient module
      this.http.post('https://api.example.com/data', { name: 'John Doe' }, { headers })
        .subscribe(response => {
          console.log(response);
        });
    
  

In this example, we create an instance of the HttpHeaders class and specify two custom headers – ‘Content-Type’ and ‘Authorization’. We then pass this HttpHeaders instance as part of the options object when making an HTTP request using the HttpClient module.

The HttpHeaders class also provides methods for adding, setting, and removing headers, as well as for creating new instances with modified headers. This allows for easy manipulation of headers when making HTTP requests in an Angular application.

Overall, the HttpHeaders class in Angular is a powerful and essential tool for managing HTTP headers and configuring HTTP requests in an Angular application.

When preparing for an Angular interview, it is important to have a solid understanding of how to use the HttpHeaders class and be able to demonstrate its usage in code examples.