https://github.com/wooorm/npm-esm-vs-cjs
Data on the share of ESM vs CJS on the public npm registry
https://github.com/wooorm/npm-esm-vs-cjs
cjs esm npm
Last synced: 29 days ago
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Data on the share of ESM vs CJS on the public npm registry
- Host: GitHub
- URL: https://github.com/wooorm/npm-esm-vs-cjs
- Owner: wooorm
- License: mit
- Created: 2022-11-05T13:03:55.000Z (over 2 years ago)
- Default Branch: main
- Last Pushed: 2025-02-28T14:03:42.000Z (2 months ago)
- Last Synced: 2025-03-28T18:14:59.614Z (about 1 month ago)
- Topics: cjs, esm, npm
- Language: JavaScript
- Homepage:
- Size: 718 KB
- Stars: 196
- Watchers: 5
- Forks: 3
- Open Issues: 0
-
Metadata Files:
- Readme: readme.md
- Funding: funding.yml
- License: license
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README
# npm-esm-vs-cjs
[![Build][badge-build-image]][badge-build-url]
Data on the share of ESM vs CJS on the public npm registry.
## Contents
* [What is this?](#what-is-this)
* [When should I use this?](#when-should-i-use-this)
* [Data](#data)
* [Scripts](#scripts)
* [Contribute](#contribute)
* [Security](#security)
* [License](#license)
## What is this?
This repository contains (historical) data on
[high-impact][github-npm-high-impact] (popular)
packages and what kind of code they expose:
* ESM — such as `type: 'module'` in `package.json`
* dual — such as both `import` and `require` conditions in export map
* faux ESM — `module` field in `package.json`,
supported by some old bundlers
* CJS — anything else (except for `@types/*`)
## When should I use this?
Use this data for rough insights on how the shift to ESM is progressing.
The data isn’t perfect though.
## Data
[`index.svg`][file-svg]:
![][file-svg]
[`index.csv`][file-csv]:
```text
date,total,esm,dual,faux,cjs
2021-08-24,5617,341,95,832,4349
2021-11-09,5647,411,119,809,4308
2022-01-27,5686,439,149,809,4289
2022-08-01,5734,496,207,791,4240
2022-11-04,5747,518,216,785,4228
2023-02-06,6085,568,255,856,4406
2023-05-29,6240,630,417,783,4410
2023-08-24,6636,676,473,876,4611
2023-11-22,6818,734,510,881,4693
2024-02-20,7042,826,594,893,4729
2024-05-27,7042,819,736,826,4661
2024-08-28,7638,923,876,876,4963
2024-11-27,8087,942,1152,843,5150
2025-02-28,8472,916,1520,852,5184
```
> 👉 **Note**:
> the crawl of `2024-05-27` adjusts several packages that were
> previously classified incorrectly as dual.
> 👉 **Note**:
> crawls from before `2022-11-04` use the list of popular packages
> on the date of `2022-11-04`,
> as I had the results of all packages,
> but not which of them were popular back then.
> Later dates will use a list of what’s popular on that date.
> 👉 **Note**:
> not all of these packages are popular.
> There are some false-positives,
> such that download counts can be gamed,
> and that `libraries.io` sometimes thinks that a fork of webpack or so is
> actually webpack.
> 👉 **Note**:
> while `@types/*` packages are filtered out in the above counts,
> it is likely that there are other packages included that aren’t really code,
> particularly in the CJS category (as that’s the default).
## Scripts
This repo includes scripts to crawl npm and analyze the results.
You need a `NPM_TOKEN` environment variable with a token to crawl npm.
[`script/crawl.js`][file-script-crawl] analyzes the `package.json` files of
`latest` releases of [high-impact][github-npm-high-impact] npm packages.
This script finishes in about 5 minutes.
You should likely first contribute to `npm-high-impact`,
which can take like 24 hours to complete.
[`script/analyze.js`][file-script-analyze] analyzes the data files and
generates SVG and CSV files from them.
After running that,
please copy/paste the new `.csv` into this readme above.
## Contribute
Yes please!
See [*How to Contribute to Open Source*][opensource-guide-contribute].
## Security
This package is safe.
## License
[MIT][file-license] © [Titus Wormer][wooorm]
[badge-build-image]: https://github.com/wooorm/npm-esm-vs-cjs/workflows/main/badge.svg
[badge-build-url]: https://github.com/wooorm/npm-esm-vs-cjs/actions
[file-csv]: index.csv
[file-license]: license
[file-script-analyze]: script/analyze.js
[file-script-crawl]: script/crawl.js
[file-svg]: index.svg
[github-npm-high-impact]: https://github.com/wooorm/npm-high-impact
[opensource-guide-contribute]: https://opensource.guide/how-to-contribute/
[wooorm]: https://wooorm.com