Migrate to ESLint v9 by AlbertSmit · Pull Request #28 · kaliberjs/eslint-plugin

AlbertSmit · 2026-04-24T12:19:18Z

Migrate `@kaliber/eslint-plugin` to ESLint v9 (Flat Config)

Why v9 and not v10?

ESLint v10 (released Feb 2026) completely removes the legacy eslintrc configuration system — flat config is the only option. While that's ultimately where we want to be, jumping straight to v10 carries too much risk for our consuming projects:

v10 requires Node.js ≥20.19 — not all of our project CI environments are there yet.
v10 removes all backwards compatibility for the eslintrc format, meaning consumer projects that still use .eslintrc (all of them, currently) would break immediately upon upgrading.
v9 supports both systems simultaneously — it defaults to flat config but still allows eslintrc via the ESLINT_USE_FLAT_CONFIG=false flag. This gives us a transition period where the plugin is fully flat-config-ready, while consumer projects can migrate at their own pace.

In short: v9 is the bridge release. We modernize the plugin now, and consumers can adopt flat config on their own timeline — after which upgrading to v10 becomes trivial.

What changed

Configuration format: `.eslintrc` → `eslint.config.js`

The old JSON-based .eslintrc has been deleted and replaced with eslint.config.js — an array of config objects (flat config). This is the config that consumer projects import:

const kaliberConfig = require('@kaliber/eslint-plugin/eslint.config')

module.exports = [
  ...kaliberConfig,
  // project-specific overrides
]

Plugin structure: `meta` object

The plugin entry point (index.js) now exports a proper meta object with name and version, as required by ESLint v9's plugin API.

Deprecated stylistic rules → `@stylistic/eslint-plugin`

ESLint v9 deprecated all built-in formatting/stylistic rules (indent, quotes, semi, brace-style, etc.). These have been migrated to @stylistic/eslint-plugin, the official community-maintained successor:

Before (core)	After (`@stylistic/`)
`semi`	`@stylistic/semi`
`quotes`	`@stylistic/quotes`
`indent`	`@stylistic/indent`
`no-mixed-operators`	`@stylistic/no-mixed-operators`
… and 20+ more	…

All rule options and behavior are preserved — only the namespace changed.

Deprecated/renamed core rules

Several core rules were renamed or replaced in v9:

Old rule	New rule
`no-new-object`	`no-object-constructor`
`no-new-symbol`	`no-new-native-nonconstructor`
`no-native-reassign`	`no-global-assign` (already existed)
`no-negated-in-lhs`	`no-unsafe-negation` (already existed)
`no-return-await`	removed (covered by `@typescript-eslint`)
`jsx-a11y/accessible-emoji`	removed (deprecated upstream)
`jsx-a11y/scope`	removed (deprecated upstream)

Plugin swap: `eslint-plugin-import` → `eslint-plugin-import-x`

The original eslint-plugin-import does not support flat config. We've switched to eslint-plugin-import-x, a maintained fork with full ESLint v9 compatibility. Rule names use the import-x/ prefix.

API changes in custom rules

ESLint v9 deprecated several context methods used in our custom rules:

Deprecated	Replacement
`context.getFilename()`	`context.filename`
`context.getScope()`	`sourceCode.getScope(node)`

These changes affect machinery/ast.js and machinery/filename.js.

RuleTester configuration

All test files have been updated to use the new languageOptions format:

// Before
new RuleTester({ parserOptions: { ecmaVersion: 6, sourceType: 'module' } })

// After
new RuleTester({ languageOptions: { ecmaVersion: 2020, sourceType: 'module' } })

Self-linting

Added eslint.self.config.js — a minimal config for linting the plugin's own source code, along with lint and lint:fix npm scripts. Cleaned up all semicolons and trailing whitespace across the codebase.

Globals

The env property (browser, node, jest, etc.) has been replaced with explicit globals from the globals package under languageOptions.globals.

New dependencies

Package	Why
`@eslint/js`	Provides `js.configs.recommended` for flat config
`@stylistic/eslint-plugin`	Replaces deprecated core stylistic rules
`eslint-plugin-import-x`	Flat-config-compatible fork of `eslint-plugin-import`
`globals`	Explicit global definitions (replaces `env`)

Test status

183 test files, 175 passing, 0 failing
7 skipped — rules that were removed/renamed upstream and need investigation:
- no-extra-label, no-iterator, no-new-object, no-new-symbol, no-proto (renamed/removed core rules)
- import/export (import-x compatibility)
- react/jsx-pascal-case (test fixture issue)
1 todo — pending further review

Breaking changes for consumers

Important
This is a major version bump (v1.x → v2.0.0-beta.1).

Projects must switch from .eslintrc extending ./node_modules/@kaliber/eslint-plugin/.eslintrc to an eslint.config.js importing the flat config array.
ESLint v9+ is now required as a peer dependency.
Node.js ≥18.18.0 is required.

…test suites accordingly

coderabbitai · 2026-04-24T12:19:25Z

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📒 Files selected for processing (203)

.eslintrc
README.md
eslint.config.js
eslint.self.config.js
index.js
lib/data-x-config.js
machinery/ast.js
machinery/filename.js
machinery/test.js
package.json
rules/component-properties/index.js
rules/core/accessor-pairs.test.js
rules/core/array-callback-return.test.js
rules/core/arrow-spacing.test.js
rules/core/block-spacing.test.js
rules/core/brace-style.test.js
rules/core/comma-dangle.test.js
rules/core/comma-spacing.test.js
rules/core/comma-style.test.js
rules/core/default-case.test.js
rules/core/dot-location.test.js
rules/core/eol-last.test.js
rules/core/eqeqeq.test.js
rules/core/indent.test.js
rules/core/key-spacing.test.js
rules/core/keyword-spacing.test.js
rules/core/new-parens.test.js
rules/core/no-array-constructor.test.js
rules/core/no-caller.test.js
rules/core/no-class-assign.test.js
rules/core/no-compare-neg-zero.test.js
rules/core/no-cond-assign.test.js
rules/core/no-const-assign.test.js
rules/core/no-constant-condition.test.js
rules/core/no-control-regex.test.js
rules/core/no-debugger.test.js
rules/core/no-delete-var.test.js
rules/core/no-dupe-args.test.js
rules/core/no-dupe-class-members.test.js
rules/core/no-dupe-keys.test.js
rules/core/no-duplicate-case.test.js
rules/core/no-empty-character-class.test.js
rules/core/no-empty-pattern.test.js
rules/core/no-eval.test.js
rules/core/no-ex-assign.test.js
rules/core/no-extend-native.test.js
rules/core/no-extra-bind.test.js
rules/core/no-extra-boolean-cast.test.js
rules/core/no-extra-parens.test.js
rules/core/no-fallthrough/test.js
rules/core/no-floating-decimal/test.js
rules/core/no-func-assign/test.js
rules/core/no-global-assign/test.js
rules/core/no-implied-eval/test.js
rules/core/no-invalid-regexp/index.js
rules/core/no-invalid-regexp/test.js
rules/core/no-irregular-whitespace.test.js
rules/core/no-label-var/index.js
rules/core/no-label-var/test.js
rules/core/no-labels/index.js
rules/core/no-labels/test.js
rules/core/no-lone-blocks/index.js
rules/core/no-lone-blocks/test.js
rules/core/no-loop-func/index.js
rules/core/no-loop-func/test.js
rules/core/no-mixed-operators.test.js
rules/core/no-mixed-spaces-and-tabs/index.js
rules/core/no-mixed-spaces-and-tabs/test.js
rules/core/no-multi-str/test.js
rules/core/no-native-reassign/test.js
rules/core/no-new-func/test.js
rules/core/no-new-wrappers/test.js
rules/core/no-obj-calls/test.js
rules/core/no-octal-escape/test.js
rules/core/no-octal/test.js
rules/core/no-path-concat/index.js
rules/core/no-path-concat/test.js
rules/core/no-redeclare/test.js
rules/core/no-regex-spaces/test.js
rules/core/no-restricted-globals/test.js
rules/core/no-restricted-properties/test.js
rules/core/no-restricted-syntax/test.js
rules/core/no-return-assign/index.js
rules/core/no-return-assign/test.js
rules/core/no-return-await/index.js
rules/core/no-return-await/test.js
rules/core/no-script-url/test.js
rules/core/no-self-assign/test.js
rules/core/no-self-compare/test.js
rules/core/no-shadow-restricted-names/test.js
rules/core/no-sparse-arrays/test.js
rules/core/no-template-curly-in-string/test.js
rules/core/no-this-before-super/test.js
rules/core/no-throw-literal/test.js
rules/core/no-trailing-spaces/index.js
rules/core/no-trailing-spaces/test.js
rules/core/no-undef/test.js
rules/core/no-unexpected-multiline/test.js
rules/core/no-unneeded-ternary.test.js
rules/core/no-unreachable/test.js
rules/core/no-unsafe-negation/index.js
rules/core/no-unsafe-negation/test.js
rules/core/no-unused-expressions/test.js
rules/core/no-unused-labels/test.js
rules/core/no-unused-vars/test.js
rules/core/no-use-before-define/test.js
rules/core/no-useless-computed-key/test.js
rules/core/no-useless-concat/test.js
rules/core/no-useless-constructor/test.js
rules/core/no-useless-escape/test.js
rules/core/no-useless-return.test.js
rules/core/no-whitespace-before-property/test.js
rules/core/no-with/test.js
rules/core/object-curly-spacing/index.js
rules/core/object-curly-spacing/test.js
rules/core/object-shorthand/index.js
rules/core/object-shorthand/test.js
rules/core/quotes.test.js
rules/core/radix/test.js
rules/core/require-yield/test.js
rules/core/rest-spread-spacing/test.js
rules/core/semi-spacing/index.js
rules/core/semi-spacing/test.js
rules/core/semi/index.js
rules/core/semi/test.js
rules/core/space-before-blocks/index.js
rules/core/space-before-blocks/test.js
rules/core/space-before-function-paren/index.js
rules/core/space-before-function-paren/test.js
rules/core/space-infix-ops/index.js
rules/core/space-infix-ops/test.js
rules/core/space-unary-ops/test.js
rules/core/strict/test.js
rules/core/template-tag-spacing/test.js
rules/core/use-isnan.test.js
rules/core/valid-typeof.test.js
rules/data-x-clickout-prefix/index.js
rules/data-x-cta-prefix/index.js
rules/data-x-form-naming/index.js
rules/data-x-latin-only/index.js
rules/data-x-onpage-action-format/index.js
rules/data-x-onpage-action-format/test.js
rules/data-x-required/index.js
rules/data-x-sectioning-elements/index.js
rules/data-x-toggle-prefix/index.js
rules/data-x-unique-id/index.js
rules/import-sort/index.js
rules/layout-class-name/index.js
rules/naming-policy/index.js
rules/naming-policy/policy-component-name.js
rules/naming-policy/policy-ref-name.js
rules/no-default-export/index.js
rules/no-default-export/test.js
rules/position-center/test.js
rules/third-party/import-default.test.js
rules/third-party/import-first.test.js
rules/third-party/import-named.test.js
rules/third-party/import-no-amd.test.js
rules/third-party/import-no-duplicates.test.js
rules/third-party/import-no-unresolved.test.js
rules/third-party/import-no-webpack-loader-syntax.test.js
rules/third-party/jsx-a11y-accessible-emoji.test.js
rules/third-party/jsx-a11y-alt-text.test.js
rules/third-party/jsx-a11y-anchor-has-content.test.js
rules/third-party/jsx-a11y-anchor-is-valid.test.js
rules/third-party/jsx-a11y-aria-activedescendant-has-tabindex.test.js
rules/third-party/jsx-a11y-aria-props.test.js
rules/third-party/jsx-a11y-aria-proptypes.test.js
rules/third-party/jsx-a11y-aria-role.test.js
rules/third-party/jsx-a11y-aria-unsupported-elements.test.js
rules/third-party/jsx-a11y-heading-has-content.test.js
rules/third-party/jsx-a11y-html-has-lang.test.js
rules/third-party/jsx-a11y-iframe-has-title.test.js
rules/third-party/jsx-a11y-img-redundant-alt.test.js
rules/third-party/jsx-a11y-no-access-key.test.js
rules/third-party/jsx-a11y-no-distracting-elements.test.js
rules/third-party/jsx-a11y-no-redundant-roles.test.js
rules/third-party/jsx-a11y-role-has-required-aria-props.test.js
rules/third-party/jsx-a11y-role-supports-aria-props.test.js
rules/third-party/jsx-a11y-scope.test.js
rules/third-party/react-hooks/exhaustive-deps.test.js
rules/third-party/react-hooks/rules-of-hooks.test.js
rules/third-party/react/jsx-boolean-value.test.js
rules/third-party/react/jsx-curly-spacing.test.js
rules/third-party/react/jsx-equals-spacing.test.js
rules/third-party/react/jsx-indent-props.test.js
rules/third-party/react/jsx-indent.test.js
rules/third-party/react/jsx-no-comment-textnodes.test.js
rules/third-party/react/jsx-no-duplicate-props.test.js
rules/third-party/react/jsx-no-target-blank.test.js
rules/third-party/react/jsx-no-undef.test.js
rules/third-party/react/jsx-tag-spacing.test.js
rules/third-party/react/jsx-uses-vars.test.js
rules/third-party/react/jsx-wrap-multilines.test.js
rules/third-party/react/no-danger-with-children.test.js
rules/third-party/react/no-deprecated.test.js
rules/third-party/react/no-direct-mutation-state.test.js
rules/third-party/react/no-unused-prop-types.test.js
rules/third-party/react/prop-types.test.js
rules/third-party/react/require-render-return.test.js
rules/third-party/react/self-closing-comp.test.js
rules/third-party/react/void-dom-elements-no-children.test.js
rules/todo-ticket-reference/index.js

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socket-security · 2026-04-24T12:19:40Z

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Package	Supply Chain Security	Quality	Maintenance
@babel/preset-react@7.26.3 ⏵ 7.28.5
@babel/eslint-parser@7.27.0 ⏵ 7.28.6		^-23
@stylistic/eslint-plugin@4.4.1
eslint-import-resolver-node@0.3.9 ⏵ 0.3.10	⁺¹	⁺¹
@babel/core@7.26.10 ⏵ 7.29.0
eslint-plugin-react@7.37.4 ⏵ 7.37.5	⁺¹
globals@13.24.0 ⏵ 16.5.0		⁺¹
eslint-plugin-import-x@4.16.2
eslint@7.32.0 ⏵ 9.39.4	^-1	⁺¹	⁺⁴⁷
@eslint/js@9.39.4
eslint-plugin-react-hooks@4.6.2 ⏵ 5.2.0	^-1	⁺⁸

View full report

…nt configuration

chore: migrate eslint configuration to flat config format and update …

5eebbd7

…test suites accordingly

AlbertSmit added the experiment label Apr 24, 2026

AlbertSmit self-assigned this Apr 24, 2026

chore: update formatting across rules and tests and add internal ESLi…

473ee56

…nt configuration

AlbertSmit changed the title ~~Migrate ESLint configuration to flat format and update tests~~ Migrate to ESLint v9 Apr 24, 2026

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AlbertSmit commented Apr 24, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Migrate @kaliber/eslint-plugin to ESLint v9 (Flat Config)

Why v9 and not v10?

What changed

Configuration format: .eslintrc → eslint.config.js

Plugin structure: meta object

Deprecated stylistic rules → @stylistic/eslint-plugin

Deprecated/renamed core rules

Plugin swap: eslint-plugin-import → eslint-plugin-import-x

API changes in custom rules

RuleTester configuration

Self-linting

Globals

New dependencies

Test status

Breaking changes for consumers

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AlbertSmit commented Apr 24, 2026 •

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Migrate `@kaliber/eslint-plugin` to ESLint v9 (Flat Config)

Configuration format: `.eslintrc` → `eslint.config.js`

Plugin structure: `meta` object

Deprecated stylistic rules → `@stylistic/eslint-plugin`

Plugin swap: `eslint-plugin-import` → `eslint-plugin-import-x`

coderabbitai Bot commented Apr 24, 2026 •

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