eslint-ts-patch

Support loading eslint.config.mjs or eslint.config.ts as flat config file for ESLint.

Configure files will be searched in the following order, the first one found will be used:

eslint.config.js
eslint.config.mjs
eslint.config.cjs
eslint.config.ts
eslint.config.mts
eslint.config.cts

For .js, .cjs, and .mjs files, they will be loaded by Node's native import().

For .ts, .cts, and .mts files, they will be loaded using jiti.

Context:

~~Unfortunately ESLint team decided to not support the detection of .cjs and .mjs as flat config~~.
Update: ESLint revised the decision to support eslint.config.mjs and eslint.config.cjs but haven't landed yet

Install

npm i -D eslint-ts-patch eslint@npm:eslint-ts-patch

It should make your eslint CLI work for those config files automatically. If it's still not, you can try switching the CLI to eslint-ts.

Compatibility

Tested with the following tools:

Package Managers

npm ✅
pnpm ✅
yarn ✅

Integrations

eslint CLI ✅
VSCode ESLint extension ✅ (as it's executing your local node_modules/.bin/eslint)

Haven't gotten chance to test with other integrations, contributions are welcome.

Versioning

This package proxies all ESLint exports, it should be compatible by aliasing the eslint package. The version of this package is the same as the latest supported ESLint version in addition to a patch number suffix indicating the patches of this package (e.g. 8.55.0-1). It's using ^ relaxed dependency of eslint, so it should work with any newer versions of ESLint.

How it works

As the support of eslint.config.js seems to be quite hard-coded in ESLint, this package proxies all exports of ESLint and installs this register beforehand. The register will swap some internal code of ESLint at runtime to make it work.

Disclaimer

It's only recommended to install this as top-level development dependency (user-aware). For plugin and library authors, it's ok to document the usage of this package for better DX. But we suggest avoiding having this as the dependency of your library or plugin, otherwise, take your own risk.

Troubleshooting

Is the Patch Working

This patch is designed to be as transparent as possible. If you want to verify if it's working, you can add DEBUG="eslint-ts-patch" environment variable to your command to see the debug logs.

➜ DEBUG="eslint-ts-patch" npx eslint -v

  eslint-ts-patch initialized +0ms
  eslint-ts-patch patched lib/eslint/flat-eslint.js +59ms

v8.55.0

antfu/eslint-ts-patch

antfu

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