Node.js Module System

Node.js has two module systems:

CommonJS Modules:

This is the traditional module system in Node.js.
Files with .cjs extension are treated as CommonJS modules.
Files with .js extension are treated as CommonJS modules unless the nearest package.json file has "type": "module".
You use require() to import modules and module.exports to export functionality.

example -
```
  // math.js
  function add(a, b) {
    return a + b;
  }

  module.exports = { add }; 

  // app.js
  const math = require('./math');
  console.log(math.add(2, 3)); // 5
```
ECMAScript Modules (ESM):
- This is the modern module system, aligned with the browser's module system.
- Files with .mjs extension are treated as ES modules.
- Files with .js extension are treated as ES modules if the nearest package.json file has "type": "module".
- You use import to import modules and export to export functionality.

  // math.mjs
  export function add(a, b) {
    return a + b;
  }

  // app.mjs
  import { add } from './math.mjs';
  console.log(add(2, 3)); // 5

Key Differences:

Syntax: ESM uses import and export, while CommonJS uses require and module.exports.
Asynchronous: ESM is asynchronous by nature, allowing for better performance.
Compatibility: ESM is the future standard, while CommonJS is still widely used.

Choosing the Right Module System:
For new projects, ESM is recommended.
For existing projects using CommonJS, you can gradually migrate to ESM.
If you need to support older Node.js versions, CommonJS is your only option.

Thank you !

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