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Path, OS & HTTP Modules

  • Node.js core modules Path, OS, and HTTP are used to handle file and directory paths, read system and environment information, and build a basic HTTP server. This content explains how requests are received, processed, and responded to within a Node.js application using the HTTP module.

  • 🔹 Node.js Path, OS & HTTP Modules

    Beginner-Friendly Book Style Explanation

    Node.js provides core modules that allow developers to work directly with the system, files, and network.
     In this chapter, we will learn three very important core modules:

    • Path Module → Work with file and directory paths

    • OS Module → Get system and environment information

    • HTTP Module → Create a basic web server

    🔹 Path Module

    Understanding File & Directory Paths

    Every file on a computer has an address, just like a home address in real life.
     This address is called a file path.

    Example:

Node.js File System Operations – index.js

This file serves as the main entry point of the Node.js application, demonstrating basic file system operations using core modules like fs to read, write, or append data efficiently. 

C:\project\node-app\index.js

  • Handling file paths manually can be unsafe and confusing, especially across different operating systems.
     Node.js solves this problem using the Path module.

    Why Use the Path Module?

    • Different OS use different path formats (Windows vs Linux)

    • Avoids errors with / and \

    • Creates safe and reliable file paths

    Learning with a Simple Story

    Imagine you are building a Node.js application and you want to:

    • Get a file name

    • Check the file extension

    • Join multiple folder paths

    • Find the full file location

    All of this becomes easy using the Path module.

    What You Can Do with Path Module

    • Extract file name from a path

    • Get file extension

    • Join multiple directory paths

    • Create absolute paths

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  • 🔹 OS Module

    System & Environment Information

    A Node.js application often needs to know details about the system it is running on.
     This information is provided by the OS module.

    What is the OS Module?

    The OS module gives access to operating system details, such as:

    • Operating system name

    • CPU information

    • Memory details

    • User information

    This is useful for monitoring, logging, and performance optimization.

    Real-Life Example

    Suppose you are running a Node.js server and you want to check:

    • How much RAM is available

    • Which operating system the server uses

    • Whether the system is under heavy load

    The OS module helps you get all this data.

    What You Can Learn Using OS Module

    • Total and free system memory

    • System architecture (32-bit / 64-bit)

    • Hostname of the system

    • Platform (Windows, Linux, macOS)

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  • 🔹 HTTP Module

    Creating a Basic Server

    One of the most powerful features of Node.js is the ability to create a server without extra software.
     This is done using the HTTP module.

    What is HTTP?

    HTTP is a communication rule that allows:

    • Browsers to send requests

    • Servers to send responses

    Node.js follows this rule to build web servers.

    Simple Explanation

    Think of:

    • Browser as a customer

    • Server as a shop

    • Request as an order

    • Response as the product

    The HTTP module manages this entire process.

    What Does an HTTP Server Do?

    1. Receives a request from the browser

    2. Understands the request (URL, method)

    3. Processes logic

    4. Sends a response back

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  • 🔹 Request & Response Flow

    How Communication Happens

    When a user types a URL like:

Request & Response Flow in Node.js

This chapter explains how communication works between the browser and a Node.js server. When a user enters a URL like http://localhost:3000, the browser sends a request to the server, and the server processes it and returns a response. 

http://localhost:3000

  • The following steps happen behind the scenes.

    Step-by-Step Request–Response Flow

    1. Browser sends a request

    2. Node.js server receives the request

    3. Server processes the request

    4. Server prepares a response

    5. Browser receives and displays the response

    Request Object (From Client)

    Contains:

    • URL

    • HTTP method (GET, POST)

    • Headers

    Response Object (From Server)

    Contains:

    • Status code (200, 404, 500)

    • Data/content

    • Headers

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  • Labels:

    • Request: Method + URL

    • Response: Status Code + Data

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