All 10 ES Modules questions
More in ES Modules
What's the difference between a named export and a default export? How do you import everything from a module under one namespace object? What is tree-shaking and why does it require ES Module syntax? How do dynamic imports (import()) differ from static import statements? Why are ES Module imports 'hoisted' and evaluated before the rest of the module's code runs? What does 'live binding' mean for ES Module exports, and how does it differ from CommonJS? How does top-level await work, and what constraint does it place on modules that import that module? What are import maps and what problem do they solve for browser-native ES Modules? Why can circular module imports (Module A imports B, which imports A) cause subtle bugs?
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JavaScript › ES Modules

What's the difference between ES Modules and CommonJS (require/module.exports)?

Intermediate

Answer

ES Modules use static import/export syntax analyzed at parse time (enabling tree-shaking), run in strict mode by default, and support top-level await. CommonJS's require() is dynamic and synchronous, resolved at runtime, and is Node.js's traditional module system.
// ES Module
import { readFile } from 'fs/promises';

// CommonJS
const { readFileSync } = require('fs');
Real-world example Migrating an older Node.js codebase from require() to import to enable modern bundler optimizations like tree-shaking.

Common follow-ups: How do you use CommonJS modules from within an ES Module file, or vice versa?

Package Management Bundlers & Transpilation (npm Webpack/Vite Babel)
All 10 ES Modules questions