feat(eslint-plugin): add minimal built-in flat presets #73873

SukkaW · 2024-12-13T01:40:48Z

Add minimal flat config presets for those who are building their own eslint flat presets and want to use their own parsers and settings.

The usage would be like:

// eslint.config.js
import eslintPluginNext from 'eslint-plugin-next';

export default [
  {
    files: [],
    plugins: {},
    settings: {},
    languageOptions: {},
    rules: {}
  },

  eslintPluginNext.flatConfigs.recommended,
  // or
  eslintPluginNext.flatConfigs.coreWebVitals,
]

ijjk · 2024-12-13T01:42:53Z

Tests Passed

ijjk · 2024-12-13T01:49:00Z

Stats from current PR

Default Build

General

	vercel/next.js canary	SukkaW/next.js eslint-plugin-presets	Change
buildDuration	19s	16s	N/A
buildDurationCached	15s	12.9s	N/A
nodeModulesSize	416 MB	416 MB	N/A
nextStartRea..uration (ms)	480ms	472ms	N/A

Client Bundles (main, webpack)

	vercel/next.js canary	SukkaW/next.js eslint-plugin-presets	Change
1187-HASH.js gzip	52.4 kB	52.4 kB	N/A
8276.HASH.js gzip	169 B	168 B	N/A
8377-HASH.js gzip	5.36 kB	5.36 kB	N/A
bccd1874-HASH.js gzip	52.8 kB	52.8 kB	N/A
framework-HASH.js gzip	57.5 kB	57.5 kB	N/A
main-app-HASH.js gzip	232 B	235 B	N/A
main-HASH.js gzip	34.1 kB	34.1 kB	N/A
webpack-HASH.js gzip	1.71 kB	1.71 kB	N/A
Overall change	0 B	0 B	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	SukkaW/next.js eslint-plugin-presets	Change
polyfills-HASH.js gzip	39.4 kB	39.4 kB	✓
Overall change	39.4 kB	39.4 kB	✓

Client Pages

	vercel/next.js canary	SukkaW/next.js eslint-plugin-presets	Change
_app-HASH.js gzip	193 B	193 B	✓
_error-HASH.js gzip	193 B	193 B	✓
amp-HASH.js gzip	512 B	510 B	N/A
css-HASH.js gzip	343 B	342 B	N/A
dynamic-HASH.js gzip	1.84 kB	1.84 kB	✓
edge-ssr-HASH.js gzip	265 B	265 B	✓
head-HASH.js gzip	363 B	362 B	N/A
hooks-HASH.js gzip	393 B	392 B	N/A
image-HASH.js gzip	4.49 kB	4.49 kB	N/A
index-HASH.js gzip	268 B	268 B	✓
link-HASH.js gzip	2.35 kB	2.34 kB	N/A
routerDirect..HASH.js gzip	328 B	328 B	✓
script-HASH.js gzip	397 B	397 B	✓
withRouter-HASH.js gzip	323 B	326 B	N/A
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Overall change	3.59 kB	3.59 kB	✓

Client Build Manifests

	vercel/next.js canary	SukkaW/next.js eslint-plugin-presets	Change
_buildManifest.js gzip	749 B	746 B	N/A
Overall change	0 B	0 B	✓

Rendered Page Sizes

	vercel/next.js canary	SukkaW/next.js eslint-plugin-presets	Change
index.html gzip	523 B	524 B	N/A
link.html gzip	538 B	538 B	✓
withRouter.html gzip	519 B	521 B	N/A
Overall change	538 B	538 B	✓

Edge SSR bundle Size

	vercel/next.js canary	SukkaW/next.js eslint-plugin-presets	Change
edge-ssr.js gzip	128 kB	128 kB	N/A
page.js gzip	206 kB	206 kB	N/A
Overall change	0 B	0 B	✓

Middleware size

	vercel/next.js canary	SukkaW/next.js eslint-plugin-presets	Change
middleware-b..fest.js gzip	669 B	666 B	N/A
middleware-r..fest.js gzip	155 B	156 B	N/A
middleware.js gzip	31.2 kB	31.2 kB	N/A
edge-runtime..pack.js gzip	844 B	844 B	✓
Overall change	844 B	844 B	✓

Next Runtimes

	vercel/next.js canary	SukkaW/next.js eslint-plugin-presets	Change
274-experime...dev.js gzip	322 B	322 B	✓
274.runtime.dev.js gzip	314 B	314 B	✓
app-page-exp...dev.js gzip	359 kB	359 kB	✓
app-page-exp..prod.js gzip	129 kB	129 kB	✓
app-page-tur..prod.js gzip	142 kB	142 kB	✓
app-page-tur..prod.js gzip	137 kB	137 kB	✓
app-page.run...dev.js gzip	347 kB	347 kB	✓
app-page.run..prod.js gzip	125 kB	125 kB	✓
app-route-ex...dev.js gzip	37.5 kB	37.5 kB	✓
app-route-ex..prod.js gzip	25.5 kB	25.5 kB	✓
app-route-tu..prod.js gzip	25.5 kB	25.5 kB	✓
app-route-tu..prod.js gzip	25.4 kB	25.4 kB	✓
app-route.ru...dev.js gzip	39.2 kB	39.2 kB	✓
app-route.ru..prod.js gzip	25.4 kB	25.4 kB	✓
pages-api-tu..prod.js gzip	9.69 kB	9.69 kB	✓
pages-api.ru...dev.js gzip	11.6 kB	11.6 kB	✓
pages-api.ru..prod.js gzip	9.68 kB	9.68 kB	✓
pages-turbo...prod.js gzip	21.7 kB	21.7 kB	✓
pages.runtim...dev.js gzip	27.5 kB	27.5 kB	✓
pages.runtim..prod.js gzip	21.7 kB	21.7 kB	✓
server.runti..prod.js gzip	916 kB	916 kB	✓
Overall change	2.44 MB	2.44 MB	✓

build cache

	vercel/next.js canary	SukkaW/next.js eslint-plugin-presets	Change
0.pack gzip	2.09 MB	2.08 MB	N/A
index.pack gzip	74.7 kB	74.2 kB	N/A
Overall change	0 B	0 B	✓

Diff details

Diff for main-HASH.js

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Commit: 2c5cd72

darthmaim · 2024-12-13T09:30:09Z

Take a look at these two comments and the surrounding discussion and also at the ESLint docs:

TLDR: ESLint prefers not to use a flatConfigs export, but instead export all configs from .configs, and suffix old eslintrc-style configs with -legacy.

SukkaW · 2024-12-13T14:56:44Z

TLDR: ESLint prefers not to use a flatConfigs export, but instead export all configs from .configs, and suffix old eslintrc-style configs with -legacy.

Adding a -legacy suffix means there will be a breaking change, which means we need to wait for another major version release. Are you willing to wait for another year?

In the meantime, attaching an extra type-safe flat preset under the configs is impossible without triggering a TypeScript error. Self-reference also doesn't work, you will get a "used-before-declare" error.

While plugin.flatConfigs is not recommended, you can import anything into the eslint.config.js, so why bother?

darthmaim · 2024-12-13T15:35:38Z

Yeah I agree, just wanted to make sure that this is considered and that there is already a plan in place to match the recommendation in the next major next.js release.

Ideally the flat config would have been part of 15.0 along with eslint 9 support, sadly eslint 9 support landed with such short notice before 15.0 that no one catched this in canary :(

rakleed · 2024-12-14T13:30:28Z

packages/eslint-plugin-next/src/index.ts

+module.exports = plugin
+module.exports.flatConfig = {
+  recommended: {
+    name: 'eslint-plugin-next recommended',


It's probably better to call it next/recommended, like other plugins do?

https://github.com/un-ts/eslint-plugin-import-x/blob/ac6d2e1b39e2a0d01b981b98b58aad0eb7939c70/src/index.ts#L161

https://github.com/Rel1cx/eslint-react/blob/c7c18c6af30d6a26108a7d47aaa0da6bd56bd404/packages/plugins/eslint-plugin/src/configs/recommended.ts#L10

https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/7566e13531f09a040daee4c16d0cba0c28d321c4/src/index.js#L303

https://github.com/sindresorhus/eslint-plugin-unicorn/blob/1774135a5ddbded2c89f82952e37a3e3bb01cdfa/index.js#L73

Same for core-web-vitals config.

Done in 8a7d85c (#73873).

@rakleed kindly ask to review and merge the changes, thanks

theoludwig · 2025-02-22T19:28:17Z

Related issue: #73655

CHC383 · 2025-02-25T23:33:53Z

packages/eslint-plugin-next/src/index.ts

+      '@next/next': plugin,
+    },
+    rules: {
+      ...recommendedRules,


Personally I think coreWebVitals should just include the coreWebVitalsRules instead of including the recommededRules, which is the same as the legacy configs, and users who want both presets could add them separately. However, I don't against the new rules set either, maybe it is up to the Next js members to decide.

CHC383 · 2025-02-25T23:41:56Z

Hi @devjiwonchoi, I saw you were involved in #73655, could you review this PR? This doesn't fix #73655 but it is at least one step towards flat configs

juliolmuller · 2025-03-08T04:33:34Z

I think this resolves #73655, #74133 and #75298.

devjiwonchoi · 2025-03-18T22:49:34Z

Sorry for the delay, and thank you for the PR!

Austin1serb · 2025-03-23T02:51:23Z

I think this resolves #73655, #74133 and #75298.

👋 Just confirming that #75298 is still reproducible with [email protected] and flat config using [email protected]. Here’s the output from running pnpm next lint:

Invalid Options:
- Unknown options: useEslintrc, extensions, resolvePluginsRelativeTo, rulePaths, ignorePath, reportUnusedDisableDirectives
- 'extensions' has been removed.
- 'resolvePluginsRelativeTo' has been removed.
- 'ignorePath' has been removed.
- 'rulePaths' has been removed. Please define your rules using plugins.
- 'reportUnusedDisableDirectives' has been removed. Please use the 'overrideConfig.linterOptions.reportUnusedDisableDirectives' option instead.

dependencies:
next 15.3.0-canary.18
eslint 8.57.0

SukkaW added 2 commits December 13, 2024 09:31

feat(eslint-plugin): built-in flat presets

5fa58fd

feat: add name to flat presets

2f42397

ijjk added CI approved Approve running CI for fork type: next labels Dec 13, 2024

SukkaW marked this pull request as draft December 13, 2024 02:09

fix: exports

0ce6aea

SukkaW marked this pull request as ready for review December 13, 2024 02:26

rakleed reviewed Dec 14, 2024

View reviewed changes

SukkaW and others added 2 commits December 14, 2024 21:38

refactor: rename presets

8a7d85c

Merge branch 'canary' into eslint-plugin-presets

2c5cd72

SukkaW requested review from CHC383 and rakleed February 23, 2025 14:28

rakleed approved these changes Feb 23, 2025

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CHC383 reviewed Feb 25, 2025

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CHC383 approved these changes Feb 25, 2025

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juliolmuller approved these changes Mar 8, 2025

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darthmaim mentioned this pull request Mar 10, 2025

feat(eslint-plugin-next): Support flat config, ship with types, and export in both ESM & CJS formats #76935

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devjiwonchoi approved these changes Mar 18, 2025

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devjiwonchoi merged commit 61e7fdb into vercel:canary Mar 18, 2025
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feat(eslint-plugin): add minimal built-in flat presets #73873

feat(eslint-plugin): add minimal built-in flat presets #73873

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Austin1serb commented Mar 23, 2025

feat(eslint-plugin): add minimal built-in flat presets #73873

feat(eslint-plugin): add minimal built-in flat presets #73873

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