Announcing v5.6.0

Core API Refactoring

The @eslint-react/core package underwent a large-scale flattening refactor. Modules previously scattered across subdirectories like component/, function/, hook/, semantic/, and api/ have been merged into the root directory. Several core APIs have been renamed:

Type utilities (type-is, type-name, type-variant) have been migrated from eslint-plugin-react-x to @eslint-react/core, and the Toolkit interface in @eslint-react/kit has been updated to reflect these naming changes.

Kit API Simplification

The @eslint-react/kit package has been streamlined:

• Simplified RuleToolkit.is API: Pre-built identifier predicates (memo, lazy, forwardRef, etc.) have been removed. Only *Call variants and API/APICall factories remain.
• Renamed initialization checkers:

Code using is.memo(node), is.lazy(node), etc. must migrate to is.memoCall(node) or use is.API("memo")(node).

Removed Rules

The following rules have been removed from their respective packages:

Class Component Support Deprecation

All Class Component-related detection functions in the core package (such as isClassComponent, isPureComponent, and various lifecycle checkers) have been marked as @deprecated, retaining only minimal compatibility support for existing rules.

Rules in eslint-plugin-react-web-api, including no-leaked-event-listener, no-leaked-interval, and no-leaked-timeout, have removed detection for Class Component lifecycles (componentDidMount / componentWillUnmount) and now only report on Hook Effects (useEffect, etc.).

New Rules

• react-x/globals: Restricts usage of global variables in React components.
• react-x/static-components: Enforces static component definitions. Enhanced with variable reference tracking and a createdHere diagnostic to reduce false positives.
• react-web-api/no-leaked-fetch: Detects leaked fetch calls in effects, closing #1714.

Kit Enhancements

• Added ast.findParent utility for traversing AST ancestors.
• Added support for Universally Unique Lexicographically Sortable Identifiers (ULID) for anonymous rules (later migrated to node:crypto randomBytes).

Bug Fixes

• react-x/error-boundaries: Fixed false positives on non-React code and resolved catch block over-reporting.
• react-x/set-state-in-effect: Improved validation accuracy.
• react-x/use-memo: Added reassignment check, aligned message IDs, and added support for for-of/for-in loops.
• Configs: Added missing rules to presets, cleaned up experimental disables, and updated documentation.
• Type expressions: Added missing Extract.unwrap for type expressions and chain expressions; unwrapped type expressions before inspecting AST node types.

Improvements

• ast: Normalized API naming conventions; renamed isJSXLike → isJSXElementOrFragment and isMethodOrProperty → isPropertyOrMethod; rewrote Check helpers.
• Extracted ESLint types and utilities into the @eslint-react/eslint package.
• Extracted @eslint-react/jsx from @eslint-react/core into a standalone utility package for static analysis of JSX patterns.
• Migrated to @ and # path aliases and replaced tsx with vite-node.
• Moved pattern utilities to rule directories and extracted rule helpers into co-located lib.ts modules across multiple plugins.
• Replaced RuleConfig with Linter.RulesRecord from ESLint.
• Restructured monorepo packages directory layout.
• react-rsc/function-definition: Added directive position and quote checks.
• Website: Added inline TOCs, improved navigation, enabled twoslash type-checking for code examples, improved accessibility, and unified layout configuration.
• Testing: Expanded compiler fixture coverage across 9 rules; added comprehensive unit tests for component/hook detection utilities.

Migration Guide

Core API migration (for custom rule authors)

• Replace isReactAPI with isAPI.
• Replace isReactAPICall with isAPICall.
• Replace isInitializedFromReact with isAPIFromReact.
• Replace isInitializedFromReactNative with isAPIFromReactNative.
• Replace ComponentDetectionHint with FunctionComponentDetectionHint.
• Replace ComponentFlag with FunctionComponentFlag.
• Replace getComponentCollector with getFunctionComponentCollector.
• Replace getComponentCollectorLegacy with getClassComponentCollector.

Kit API migration

• Replace is.memo(node), is.lazy(node), etc. with is.memoCall(node) or is.API("memo")(node).
• Replace initializedFromReact with APIFromReact.
• Replace initializedFromReactNative with APIFromReactNative.
• Replace RuleDefinition type with RuleFunction.

Removed rules

• Remove react-x/component-hook-factories.
• Remove react-x/no-redundant-should-component-update.
• Remove react-x/no-unnecessary-use-callback.
• Remove react-x/no-unnecessary-use-memo.
• Remove react-x/no-unused-state (re-added as a no-op rule in v5.6.6).
• Remove react-x/prefer-destructuring-assignment.
• Remove react-x/prefer-namespace-import and react-dom/prefer-namespace-import.
• Remove react-debug/class-component.

Class Component deprecation

• Review any reliance on Class Component lifecycle detection in react-web-api/no-leaked-event-listener, react-web-api/no-leaked-interval, and react-web-api/no-leaked-timeout. These rules now only report on Hook Effects.

References

• Changelog: v5.6.0
• Full Changelog: v4.2.1...v5.6.0