Introduction

HTTP client is a feature of Angular that allows you to make HTTP requests and handle responses. It provides a simple way to communicate with web servers and retrieve data from external APIs. In Angular, the HTTP client is included in the @angular/common/http package.

Tabular Comparison

Here’s a comparison table that shows the differences between traditional AJAX requests and Angular’s HTTP client:

	Traditional AJAX Requests	Angular HTTP Client
Import Statement	XMLHttpRequest	HttpClient
Request Method	open(), send()	get(), post(), put(), delete()
Response Handling	Callbacks	Observables
Error Handling	Callbacks	Observables
URL Encoding	Manual	Automatic
Progress Events	Manual	Automatic

As you can see from the table, traditional AJAX requests require you to manually handle many aspects of the request and response, while Angular’s HTTP client provides a higher-level API that simplifies the process.

Text Diagram

Here’s a text diagram that shows how the Angular HTTP client can be used to make a request and handle the response:

+-------------+   +---------------+   +-------------+
| HTTP Request|-->| HTTP Client   |-->| HTTP Response|
+-------------+   +---------------+   +-------------+
                                  |
                                  v
                          +----------------+
                          | Error Handling |
                          +----------------+

In this diagram, we start with an HTTP request that is sent to the HTTP client. The client sends the request to the server and receives a response. The response is then passed back to the client, which can handle it appropriately. If there is an error, the error handling mechanism is triggered.

Complete Code Program

Here’s a complete code program that shows how to use the Angular HTTP client to make a GET request and handle the response:

import { Component } from '@angular/core';
import { HttpClient } from '@angular/common/http';

@Component({
  selector: 'app-root',
  template: `
    <button (click)="getData()">Get Data</button>
    <div *ngIf="data">
      <h2>{{ data.title }}</h2>
      <p>{{ data.body }}</p>
    </div>
  `
})
export class AppComponent {
  data: any;

  constructor(private http: HttpClient) {}

  getData() {
    this.http.get('https://jsonplaceholder.typicode.com/posts/1').subscribe(response => {
      this.data = response;
    });
  }
}

In this code program, we import the HttpClient class from the @angular/common/http package. We then define a component that has a button that, when clicked, calls the getData method. This method sends a GET request to the https://jsonplaceholder.typicode.com/posts/1 URL using the get method of the HTTP client. We subscribe to the observable that is returned by the get method, and when we receive a response, we assign it to the data property of the component. The HTML template uses the *ngIf directive to only display the data if it exists.

Conclusion

In conclusion, the Angular HTTP client is a powerful feature that allows you to easily make HTTP requests and handle responses. By using the HTTP client effectively, you can create dynamic and interactive web applications that retrieve data from external APIs and provide a seamless and intuitive user experience.