Dual Publish

Services & Skills

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  • Tested on projects with 16M downloads per month.
  • CI tests show it working with Node.js, browsers, React Native,
    bundlers (webpack, Parcel, Rollup, or esbuild) and CDNs (like jspm).
  • Does not change line numbers in stacktrace and keeps sources readable.
  • No build step. No need for separated src/ and dist/ directories in the repository. You will be able to test a branch by installing a version from GitHub: npm i example@you/example#fix.
  • Multiple files support. Your users will be able to import separated files via import { nanoid } from 'nanoid/async'.
  • Cleans npm package from development configs before publishing.
  • Supports process.env.NODE_ENV for development checks, which you would want to remove in a production JS bundle.

You write CommonJS in your npm library sources:

// index.js
module.exports = { lib }

npx dual-publish compiles your library when publishing to npm:

// index.js
export { lib }

// index.cjs
module.exports = { lib }

// package.json
{"type": "module",
  "module": "index.js",
  "main": "index.cjs",
  "exports": {
    "require": "./index.cjs",
    "import": "./index.js"
  }
}

Now your library can be imported natively as ESM or CommonJS:

// CommonJS
let { lib } = require('lib')

// ESM in Node.js, webpack, Parcel, and Rollup
import { lib } from 'lib'

// ESM in browser
import { lib } from 'https://cdn.jsdelivr.net/npm/lib/index.js'
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Martians at a glance
16
years in business

A product development consultancy that works with startups and established businesses, while also creating open source-based products and services