What do you think of AMD vs CommonJS?

TL;DR

AMD (Asynchronous Module Definition) and CommonJS are two JavaScript module systems. AMD is designed for asynchronous loading of modules, making it suitable for browsers. CommonJS is designed for synchronous loading, making it more suitable for server-side environments like Node.js. AMD uses define and require for defining and loading modules, while CommonJS uses module.exports and require.

AMD vs CommonJS

Overview

Both AMD and CommonJS are module systems used in JavaScript to manage dependencies and organize code. They serve different purposes and are suited to different environments.

AMD (Asynchronous Module Definition)

Characteristics

• Designed for asynchronous loading of modules
• Primarily used in browser environments
• Uses define and require for defining and loading modules

Example

// Defining a module in AMD
define(['dependency1', 'dependency2'], function (dep1, dep2) {
  return {
    // Module code here
  };
});

// Loading a module in AMD
require(['module1', 'module2'], function (mod1, mod2) {
  // Code that uses mod1 and mod2
});

CommonJS

Characteristics

• Designed for synchronous loading of modules
• Primarily used in server-side environments like Node.js
• Uses module.exports and require for defining and loading modules

Example

// Defining a module in CommonJS
const dep1 = require('dependency1');
const dep2 = require('dependency2');

module.exports = {
  // Module code here
};

// Loading a module in CommonJS
const mod1 = require('module1');
const mod2 = require('module2');

// Code that uses mod1 and mod2

Key differences

Loading mechanism

• AMD: Asynchronous, suitable for browsers where non-blocking operations are crucial.
• CommonJS: Synchronous, suitable for server-side environments where modules are loaded before execution.

Environment suitability

• AMD: Better for client-side applications.
• CommonJS: Better for server-side applications.

Syntax

• AMD: Uses define and require.
• CommonJS: Uses module.exports and require.

Use cases

AMD

• Suitable for web applications where you need to load modules asynchronously to avoid blocking the UI.
• Often used with module loaders like RequireJS.

CommonJS

• Suitable for server-side applications where modules are loaded once at the start.
• The standard module system for Node.js.

Further reading

• RequireJS documentation
• Node.js modules documentation
• MDN Web Docs on JavaScript modules