10-modules.md

🐢 Node.js

Modules (CJS & ESM)

In Node.js there are two ways to manage modules:

• CJS for Common JavaScript
• ESM for ECMAScript modules

ESM is the new standard integrated since ECMAScript 6 for module management. However, historically Node.js has been using CJS since the beginning and at the time there were a lot of concerns about the ESM specification (which made the implementation in the Node js ecosystem complex).

const { foo } = require("mymodule");

exports.foo = function boo() {
    return foo();
}

With CJS it is necessary to use the require() function and keywords like module.exports while in ESM you can use the import and export keywords.

import { foo } from "mymodule";

export function boo() {
    return foo();
}

ESM support on Node.js is becoming more and more stable and it is therefore not surprising that it will become the default module system in the near future.

I recommend you to listen to the following talks to better understand the subject:

• Extra Special Modules - Myles Borins, Google
• Keynote: The Future of JavaScript is Universal - Myles Borins, Developer Advocate, Google
• ES Modules in Node.js - Gil Tayar

Articles related to ESM

• Get Ready For ESM - Sindresorhus
• Pure ESM package - Sindresorhus
• Using ES Modules (ESM) in Node.js: A Practical Guide (Part 1

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