Angular Interceptors Unleashed: Solving Complex Scenarios with Ease. Practical Use Cases and Examples (2023)

Angular Interceptors Unleashed: Solving Complex Scenarios with Ease. Practical Use Cases and Examples (2023) Photo Credits: Astrit Shuli

Angular is a powerful and popular JavaScript framework used for building dynamic web applications. One of its key features is the HttpClient module, which provides an easy way to make HTTP requests to external APIs or your server. Angular interceptors are a crucial part of this module, allowing you to intercept and manipulate HTTP requests and responses. In this article, we’ll explore the most common use cases for Angular interceptors and provide code examples to help you get started.

What Are Angular Interceptors?

Angular interceptors are middleware-like services that can be used to intercept and modify HTTP requests and responses globally within your application. They are useful for implementing cross-cutting concerns such as authentication, error handling, logging, and caching.

Interceptors work by defining a series of functions that can be executed before or after an HTTP request is sent or a response is received. These functions are organized into two main categories:

1. Request Interceptors: These functions are executed before the HTTP request is sent. You can use them to modify the request headers, add authentication tokens, or perform any other necessary pre-processing.
2. Response Interceptors: These functions are executed after the HTTP response is received but before it is passed to the calling code. They allow you to inspect and modify the response, handle errors, or perform post-processing.

Now, let’s dive into some common use cases for Angular interceptors and provide code examples for each.

Common Use Cases for Angular Interceptors

1. Authentication Interceptor

An authentication interceptor is used to add authentication tokens to outgoing requests and handle authentication-related errors. This is essential for securing your application’s API requests.

import { Injectable } from '@angular/core';
import {
  HttpInterceptor,
  HttpRequest,
  HttpHandler,
} from '@angular/common/http';

@Injectable()
export class AuthInterceptor implements…