In this article, we are going to discuss the basics of HTTP Interceptors in Angular .

Agenda

· What is Angular?

· What is an HTTP Interceptor?

· HTTP Interceptors in Angular

· Benefits of HTTP Interceptors

· Practical Implementation

Prerequisites

· Basic understanding of TypeScript and Angular

· Angular CLI

· NodeJS

· VS Code

What is Angular?

Angular is a popular open-source JavaScript framework for building web applications. It was developed by Google and is currently maintained by the Angular Team at Google. Angular allows developers to create dynamic, single-page applications (SPAs) and provides a structured approach to building complex web applications.

What is an HTTP Interceptor?

• HTTP Interceptors are a concept in web development and server-side programming, typically associated with web frameworks and libraries.

• These interceptors allow developers to intercept and handle HTTP requests and responses globally within an application.

HTTP Interceptors in Angular

• HTTP Interceptors in Angular are classes that implement the HttpInterceptor interface.

• They can be used to perform various tasks related to HTTP requests and responses, such as adding headers, handling errors, modifying the request or response data, logging, authentication, etc.

• HttpInterceptor defines a single method called intercept, which takes two parameters: the HttpRequest and the HttpHandler.

Benefits of HTTP Interceptors

Following are some of the key benefits of using HTTP Interceptors in Angular:

• Testability and reusability: Interceptors are easy to test in isolation, allowing you to ensure that each interceptor behaves correctly.

• Centralized code for cross-cutting concerns: HTTP Interceptors allow you to define logic for common tasks, such as authentication, logging, error handling, or adding headers, in a centralized location.

• Global application-level modifications: Interceptors operate globally, intercepting all HTTP requests and responses made by the Angular application. This means you can apply changes or perform actions consistently across multiple API calls without having to modify each individual request or response manually.

• Error handling and logging: Interceptors can be utilized to handle errors globally, providing a consistent approach to error reporting and handling throughout the application.

• Caching and request/response manipulation: HTTP Interceptors can be leveraged to implement caching mechanisms, reducing redundant requests and optimizing the application’s performance.

• Separation of concerns: By using HTTP Interceptors, you can keep concerns related to data fetching and communication (HTTP) separate from the business logic of your components and services.

• Security and authentication: Interceptors are commonly used for adding authorization headers or authentication tokens to outgoing requests. This ensures that the user’s authentication status is automatically included in API calls without the need to explicitly set headers in every request.

• Easy integration with third-party libraries: Interceptors can be used to integrate with third-party libraries or APIs seamlessly. For example, you can apply a specific format to API responses that are expected by a charting library or a data visualization tool.