2020-05-28-esm-for-nodejs.md

ECMAScript modules for Node.js

I decided to completely drop CommonJS from January 2022.

What will change?

All my modules will only support Node.js v14 and v16 beginning from January 2022.

New Packages will only support Node.js v14 and v16 from the start.

How do I do it?

Like so:

// package.json
{
  "type": "module",
  "engines": {
    "node": "^14.15 || >=16"
  }
}

// .npmrc
engine-strict=true

// tsconfig.json
{
  "compilerOptions": {
    "target": "ES2020",
    "module": "es2020",
    "moduleResolution": "node",

    "rootDir": "src",
    "outDir": "dist",

    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true,
    "newLine": "lf"
  },
  "include": ["src/**/*"],
  "exclude": ["node_modules", "**/*.spec.ts"]
}

Replace dirname and filename

import { dirname } from 'path'
import { fileURLToPath } from 'url'
const __filename = fileURLToPath(import.meta.url)
const __dirname = dirname(__filename)

Include ES Modules into a CommonJS codebase?

Yes, it is possible using Dynamic Imports.

Example:

// index.cjs

const main = async () => {
  const esmPackage = await import('esm-package')
  // or maybe
  const { module } = await import('esm-package')

  // now use the esm-package like you are used to
}

main()

Badge

I will probably add the badge below to ESModule-Only packages:

/