Difference between global modules and core modules (built-in modules) in nodejs

In Node.js, the terms "global modules" and "core modules" (or "built-in modules") refer to two different concepts that are both integral to the runtime environment.

Core Modules (Built-in Modules)

Core modules are modules that are included with the Node.js runtime itself. These modules provide a variety of essential functionalities that are common in many applications. They are designed to be efficient and are maintained as part of the Node.js project.

Characteristics of Core Modules:

1. Precompiled: Core modules are compiled into the Node.js binary, which means they are loaded very quickly.
2. No Installation Required: Core modules come bundled with Node.js, so you don’t need to install them separately.
3. Explicitly Required: Core modules must be explicitly required in your code using the require function.

Examples of Core Modules:

• http: For creating HTTP servers and clients.
• fs: For interacting with the file system.
• path: For working with file and directory paths.
• os: For operating system-related utilities.
• crypto: For cryptographic functionalities.
• net: For creating servers and clients for lower-level networking.
• url: For URL resolution and parsing.

Example Usage:

const http = require('http');
const fs = require('fs');
const path = require('path');

Global Modules

Global modules refer to objects and functions that are automatically available in the global scope, meaning they can be used directly without the need to require them. These global objects are part of the Node.js runtime environment and provide a range of utility functions and information about the runtime process.

Characteristics of Global Modules:

1. Globally Available: Global modules and objects can be accessed anywhere in your code without requiring them.
2. Built-in: They are part of the Node.js runtime and do not need to be imported or installed.
3. Always Available: These globals are always present and cannot be overridden by user code.

Examples of Global Modules:

• global: The global namespace object.
• process: Provides information and control over the current Node.js process.
• console: Provides a simple debugging console (e.g., console.log).
• Buffer: For handling binary data.
• setTimeout, clearTimeout: For scheduling and canceling functions.
• setInterval, clearInterval: For scheduling and canceling repeated execution of functions.
• setImmediate, clearImmediate: For scheduling and canceling immediate execution of functions.
• __dirname: The directory name of the current module.
• __filename: The file name of the current module.

Example Usage:

console.log('This is a global object');

setTimeout(() => {
  console.log('This message is delayed by 2 seconds');
}, 2000);

console.log(__dirname);
console.log(__filename);