Add support for Flat Config (eslint v9) #54297

pipopotamasu · 2025-10-28T03:19:43Z

Summary:

Implements: #42996

Add support for Flat config (eslint v9) to eslint-config-react-native. To achieve this, I created packages/eslint-config-react-native/flat.js to export flat config as well as maintain legacy config for backward compatibility. I recognize we have had the PR for supporting Flat config already, but it looks stale and doesn't seem likely to move forward. That's why I created this PR.

I also updated eslint-plugin-react-native and eslint-plugin-specs so that they comply with the current eslint plugin format.

Changelog:

[GENERAL] [ADDED] - Add support for Flat Config (eslint v9)

Test Plan:

Pull this branch into your local machine
cd packages/eslint-config-react-native
yarn link
Clone https://github.com/pipopotamasu/rn-eslint-config-test in your local machine
cd path/to/rn-eslint-config-test
yarn install
yarn link "@react-native/eslint-config"
yarn lint
Confirm that eslint rules from @react-native/eslint-config are applied

meta-cla · 2025-10-28T03:19:49Z

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pipopotamasu · 2025-10-28T03:22:42Z

packages/eslint-config-react-native/package.json

    "eslint-plugin-jest": "^29.0.1",
    "eslint-plugin-react": "^7.30.1",
    "eslint-plugin-react-hooks": "^5.2.0",
-    "eslint-plugin-react-native": "^4.0.0"


Upgraded eslint-plugin-react-native because v4 doesn't support eslint v9

meta-cla · 2025-10-28T05:17:46Z

Thank you for signing our Contributor License Agreement. We can now accept your code for this (and any) Meta Open Source project. Thanks!

tysoncung

This is an excellent PR that addresses a critical need for ESLint 9 compatibility. The implementation is well-structured with backward compatibility maintained.

tysoncung

LGTM

huntie

LGTM and have confirmed that the eslint-plugin-react-native 4→5 diff is structural only.

(Sidenote: Wow, we should both aim to upstream this pkg and simplify our config. But let's not change this now.)

meta-codesync · 2025-10-30T10:53:58Z

@huntie has imported this pull request. If you are a Meta employee, you can view this in D85851077.

pipopotamasu · 2025-11-01T19:25:17Z

@huntie Thank you for your quick review and approval. Looks like some Facebook internal CI checks failed. Feel free to tell me if you want me to fix something to pass these checks

huntie · 2025-11-03T12:24:22Z

@pipopotamasu Working on it (any dep bumps need re-syncing/alignment within our main repo). I'll reach out if there are any functional errors from this change.

react-native-bot · 2025-11-08T20:56:24Z

	Warnings
⚠️	❗ JavaScript API change detected - This PR commits an update to ReactNativeApi.d.ts, indicating a change to React Native's public JavaScript API. Please include a clear changelog message. This change will be subject to extra review. This change was flagged as: `BREAKING`

Generated by 🚫 dangerJS against 1b6f1e3

pipopotamasu · 2025-11-08T21:38:01Z

Warnings
⚠️ ❗ JavaScript API change detected - This PR commits an update to ReactNativeApi.d.ts, indicating a change to React Native's public JavaScript API. Please include a clear changelog message. This change will be subject to extra review.
This change was flagged as: BREAKING

Generated by 🚫 dangerJS against 1b6f1e3

Hmm, danger is flagging the merge commit of main branch as BREAKING change. I think this is a false-positive warning

meta-codesync · 2025-11-13T18:51:11Z

@huntie merged this pull request in 1859245.

react-native-bot · 2025-11-13T18:51:11Z

This pull request was successfully merged by @pipopotamasu in 1859245

^{When will my fix make it into a release? | How to file a pick request?}

Summary: Implements: facebook/react-native#42996 Add support for Flat config (eslint v9) to `eslint-config-react-native`. To achieve this, I created `packages/eslint-config-react-native/flat.js` to export flat config as well as maintain legacy config for backward compatibility. I recognize we have had [the PR for supporting Flat config](facebook/react-native#42996) already, but it looks stale and doesn't seem likely to move forward. That's why I created this PR. I also updated `eslint-plugin-react-native` and `eslint-plugin-specs` so that they comply with the current eslint plugin format. ## Changelog: [GENERAL] [ADDED] - Add support for Flat Config (eslint v9) Pull Request resolved: facebook/react-native#54297 Test Plan: 1. Pull this branch into your local machine 2. `cd packages/eslint-config-react-native` 3. `yarn link` 4. Clone https://github.com/pipopotamasu/rn-eslint-config-test in your local machine 5. `cd path/to/rn-eslint-config-test` 6. `yarn install` 7. `yarn link "react-native/eslint-config"` 8. `yarn lint` 9. Confirm that eslint rules from `react-native/eslint-config` are applied <img width="1470" height="628" alt="image" src="https://github.com/user-attachments/assets/955fd655-8a79-4dd4-9031-e505d218d63a" /> Reviewed By: vzaidman Differential Revision: D85851077 Pulled By: huntie fbshipit-source-id: 9c78ecc4f5c3b10175a89417628b599735f95215

pipopotamasu added 6 commits October 25, 2025 17:47

make eslint-plugin-specs flat config style

c62c3f8

make eslint-plugin-react-native flat config style

2f74024

make eslint-config-react-native flat config style

f15e001

prettier

8b6a326

upgrade eslint-plugin-react-native for eslint v9 compatibility

7fc41fc

fix files glob

07b6fa0

pipopotamasu commented Oct 28, 2025

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meta-cla bot added the CLA Signed This label is managed by the Facebook bot. Authors need to sign the CLA before a PR can be reviewed. label Oct 28, 2025

facebook-github-bot added the Shared with Meta Applied via automation to indicate that an Issue or Pull Request has been shared with the team. label Oct 28, 2025

This was referenced Oct 28, 2025

eslint-config/eslint-plugin: Support "Flat Config" (ESLint 9) #42996

Open

Updating eslint packages to flat config file #43959

Closed

Merge branch 'main' into eslint-flat-config

1b6f1e3

tysoncung reviewed Oct 29, 2025

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tysoncung reviewed Oct 30, 2025

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huntie approved these changes Oct 30, 2025

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meta-codesync bot closed this in 1859245 Nov 13, 2025

facebook-github-bot added the Merged This PR has been merged. label Nov 13, 2025

Add support for Flat Config (eslint v9) #54297

Add support for Flat Config (eslint v9) #54297

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