1. Introduction

In this tutorial, we will learn how to handle HTTP requests and responses. HTTP requests are the way that we send data and requests to servers, and responses are what servers send back to us.

You'll learn how to parse request data, perform backend operations, and send responses. By the end of this tutorial, you'll be comfortable with HTTP requests and responses, and you'll have a better understanding of how data is moved around on the web.

Prerequisites: Basic understanding of web development and JavaScript.

2. Step-by-Step Guide

HTTP stands for HyperText Transfer Protocol, and it's essentially a protocol for transferring data over the web. It works via a request-response cycle: a client (like a browser) sends an HTTP request to a server, and the server sends an HTTP response back to the client. The request includes details like what method to use (GET, POST, etc.), the URL, and any data the client wants to send. The response includes a status code, any data the server wants to send back, and other information.

2.1 HTTP Requests

A HTTP request is made up of several parts:

• Method: The type of request. Common methods include GET (retrieve data), POST (send data), PUT (update data), and DELETE (remove data).
• URL: The location of the data.
• Headers: Additional information, like what kind of response the client can understand.
• Body: The data to send (for POST and PUT requests).

2.2 HTTP Responses

A HTTP response also has several parts:

• Status code: A three-digit code indicating the result of the request. Common status codes include 200 (OK), 404 (Not Found), and 500 (Internal Server Error).
• Headers: Additional information, like the type of the returned data.
• Body: The returned data.

3. Code Examples

Here's an example of a GET request using JavaScript's fetch function:

// Make a GET request to the specified URL
fetch('https://api.example.com/data')
  .then(response => {
    // The fetch promise resolves with the response stream as soon as headers are received
    // To read the content of the body, we need to call .json() (for JSON data) which itself returns a promise
    return response.json();
  })
  .then(data => {
    // Here we have the data that was returned by the server
    console.log(data);
  })
  .catch(error => {
    // If something goes wrong, the error can be caught here
    console.log('Error:', error);
  });

4. Summary

In this tutorial, you learned about the HTTP protocol, and how to make requests and handle responses using JavaScript. You learned about the different parts of HTTP requests and responses, and how to parse JSON data from a response.

5. Practice Exercises

1. Make a POST request to a test server like https://jsonplaceholder.typicode.com/posts. Send some data in the body of the request and log the response to the console.

2. Make a GET request to the same server and log the response. Try to handle any errors that might occur.

3. Try to make a DELETE request. What status code do you get back? What does that mean?

Remember, practice is key when learning new concepts in programming. Keep practicing and you'll get the hang of handling HTTP requests and responses.