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What is the difference between ES modules and CommonJS?

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01

Understand the problem

Compare module systems.

modules
02

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04

Read the code

Same module, two systems
// ── ES Modules (the standard) ──
export const add = (a, b) => a + b;
export default function multiply(a, b) { return a * b; }
import multiply, { add } from "./math.js";

// ── CommonJS (Node legacy) ──
const add2 = (a, b) => a + b;
module.exports = { add: add2 };
module.exports.multiply = (a, b) => a * b;
const { add: addCjs } = require("./math.js");

// ESM resolves imports statically (tree-shakeable, supports top-level await);
// CJS require() is a synchronous function call resolved at runtime.
05

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