typescript-eslint · kirkwaiblinger · May 16, 2025 · May 7, 2025 · May 7, 2025 · May 7, 2025
diff --git a/eslint.config.mjs b/eslint.config.mjs
@@ -1,9 +1,9 @@
 // @ts-check
 
+import eslintCommentsPlugin from '@eslint-community/eslint-plugin-eslint-comments/configs';
 import { fixupConfigRules, fixupPluginRules } from '@eslint/compat';
 import { FlatCompat } from '@eslint/eslintrc';
 import eslint from '@eslint/js';
-import eslintCommentsPlugin from '@eslint-community/eslint-plugin-eslint-comments/configs';
 import tseslintInternalPlugin from '@typescript-eslint/eslint-plugin-internal';
 import vitestPlugin from '@vitest/eslint-plugin';
 import eslintPluginPlugin from 'eslint-plugin-eslint-plugin';
@@ -594,10 +594,10 @@ export default tseslint.config(
     rules: {
       '@typescript-eslint/internal/prefer-ast-types-enum': 'off',
       'import/no-default-export': 'off',
+      'react-hooks/exhaustive-deps': 'warn', // TODO: enable it later
       'react/jsx-no-target-blank': 'off',
       'react/no-unescaped-entities': 'off',
       'react/prop-types': 'off',
-      'react-hooks/exhaustive-deps': 'warn', // TODO: enable it later
     },
     settings: {
       react: {
@@ -632,7 +632,26 @@ export default tseslint.config(
     name: 'all-files',
     rules: {
       '@typescript-eslint/sort-type-constituents': 'off',
-      'perfectionist/sort-classes': 'error',
+      'perfectionist/sort-classes': [
+        'error',
+        {
+          groups: [
+            'index-signature',
+            'static-property',
+            'static-block',
+            ['protected-property', 'protected-accessor-property'],
+            ['private-property', 'private-accessor-property'],
+            ['property', 'accessor-property'],
+            'constructor',
+            'static-method',
+            'protected-method',
+            'private-method',
+            'method',
+            ['get-method', 'set-method'],
+            'unknown',
+          ],
+        },
+      ],
       'perfectionist/sort-enums': 'off',
       'perfectionist/sort-objects': 'error',
       'perfectionist/sort-union-types': [
@@ -644,6 +663,20 @@ export default tseslint.config(
       ],
     },
   },
+  {
+    files: ['packages/ast-spec/src/**/*.ts'],
+    rules: {
+      'perfectionist/sort-interfaces': [
+        'error',
+        {
+          customGroups: {
+            first: ['^type$'],
+          },
+          groups: ['first', 'unknown'],
+        },
+      ],
+    },
+  },
   {
     files: [
       'packages/eslint-plugin/src/rules/*.ts',
@@ -655,10 +688,10 @@ export default tseslint.config(
         'error',
         {
           customGroups: {
-            first: ['loc', 'name', 'node', 'type'],
-            fourth: ['fix'],
-            second: ['meta', 'messageId', 'start'],
-            third: ['defaultOptions', 'data', 'end'],
+            first: ['^loc$', '^name$', '^node$', '^type$'],
+            fourth: ['^fix$'],
+            second: ['^meta$', '^messageId$', '^start$'],
+            third: ['^defaultOptions$', '^data$', '^end$'],
           },
           groups: ['first', 'second', 'third', 'fourth', 'unknown'],
         },
@@ -672,7 +705,7 @@ export default tseslint.config(
       'perfectionist/sort-objects': [
         'error',
         {
-          customGroups: { top: ['valid'] },
+          customGroups: { top: ['^valid$'] },
           groups: ['top', 'unknown'],
         },
       ],
@@ -686,8 +719,8 @@ export default tseslint.config(
         'error',
         {
           customGroups: {
-            first: ['type'],
-            second: ['loc', 'range'],
+            first: ['^type$'],
+            second: ['^loc$', '^range$'],
           },
           groups: ['first', 'second'],
         },

diff --git a/package.json b/package.json
@@ -84,7 +84,7 @@
     "eslint-plugin-import": "^2.31.0",
     "eslint-plugin-jsdoc": "^50.5.0",
     "eslint-plugin-jsx-a11y": "^6.10.2",
-    "eslint-plugin-perfectionist": "^3.9.1",
+    "eslint-plugin-perfectionist": "^4.12.3",
     "eslint-plugin-react": "^7.37.3",
     "eslint-plugin-react-hooks": "^5.0.0",
     "eslint-plugin-regexp": "^2.7.0",

diff --git a/packages/ast-spec/src/expression/UnaryExpression/spec.ts b/packages/ast-spec/src/expression/UnaryExpression/spec.ts
@@ -3,5 +3,5 @@ import type { UnaryExpressionBase } from '../../base/UnaryExpressionBase';
 
 export interface UnaryExpression extends UnaryExpressionBase {
   type: AST_NODE_TYPES.UnaryExpression;
-  operator: '!' | '+' | '~' | '-' | 'delete' | 'typeof' | 'void';
+  operator: '!' | '+' | '-' | 'delete' | 'typeof' | 'void' | '~';
 }
diff --git a/packages/eslint-plugin/src/rules/no-restricted-types.ts b/packages/eslint-plugin/src/rules/no-restricted-types.ts
@@ -36,7 +36,7 @@ function stringifyNode(
 }
 
 function getCustomMessage(
-  bannedType: string | { fixWith?: string; message?: string } | true | null,
+  bannedType: string | true | { fixWith?: string; message?: string } | null,
 ): string {
   if (!bannedType || bannedType === true) {
     return '';

diff --git a/packages/eslint-plugin/src/rules/prefer-nullish-coalescing.ts b/packages/eslint-plugin/src/rules/prefer-nullish-coalescing.ts
@@ -47,13 +47,13 @@ export type Options = [
     ignoreIfStatements?: boolean;
     ignoreMixedLogicalExpressions?: boolean;
     ignorePrimitives?:
+      | true
       | {
           bigint?: boolean;
           boolean?: boolean;
           number?: boolean;
           string?: boolean;
-        }
-      | true;
+        };
     ignoreTernaryTests?: boolean;
   },
 ];

diff --git a/packages/eslint-plugin/src/util/collectUnusedVariables.ts b/packages/eslint-plugin/src/util/collectUnusedVariables.ts
@@ -230,9 +230,7 @@ class UnusedVarsVisitor extends Visitor {
   private markVariableAsUsed(
     variableOrIdentifier: ScopeVariable | TSESTree.Identifier,
   ): void;
-
   private markVariableAsUsed(name: string, parent: TSESTree.Node): void;
-
   private markVariableAsUsed(
     variableOrIdentifierOrName: string | ScopeVariable | TSESTree.Identifier,
     parent?: TSESTree.Node,

diff --git a/packages/eslint-plugin/tests/RuleTester.ts b/packages/eslint-plugin/tests/RuleTester.ts
@@ -46,10 +46,10 @@ export function batchedSingleLineTests<
   Options extends readonly unknown[],
 >(
   options:
+    | ValidTestCase<Options>
     | ({
         output?: string | null;
-      } & Omit<InvalidTestCase<MessageIds, Options>, 'output'>)
-    | ValidTestCase<Options>,
+      } & Omit<InvalidTestCase<MessageIds, Options>, 'output'>),
 ): (InvalidTestCase<MessageIds, Options> | ValidTestCase<Options>)[] {
   // -- eslint counts lines from 1
   const lineOffset = options.code.startsWith('\n') ? 2 : 1;

diff --git a/packages/eslint-plugin/typings/eslint-rules.d.ts b/packages/eslint-plugin/typings/eslint-rules.d.ts
@@ -520,11 +520,11 @@ declare module 'eslint/lib/rules/prefer-destructuring' {
     object?: boolean;
   }
   type Option0 =
+    | DestructuringTypeConfig
     | {
         AssignmentExpression?: DestructuringTypeConfig;
         VariableDeclarator?: DestructuringTypeConfig;
-      }
-    | DestructuringTypeConfig;
+      };
   export interface Option1 {
     enforceForRenamedProperties?: boolean;
   }
@@ -554,22 +554,22 @@ declare module 'eslint/lib/rules/no-restricted-imports' {
         }
     )[];
     export type ArrayOfStringOrObjectPatterns =
+      | string[]
       | {
           // extended
           allowTypeImports?: boolean;
           caseSensitive?: boolean;
           group?: string[];
           regex?: string;
           message?: string;
-        }[]
-      | string[];
+        }[];
     export type RuleListener =
+      | Record<string, never>
       | {
           ExportAllDeclaration(node: TSESTree.ExportAllDeclaration): void;
           ExportNamedDeclaration(node: TSESTree.ExportNamedDeclaration): void;
           ImportDeclaration(node: TSESTree.ImportDeclaration): void;
-        }
-      | Record<string, never>;
+        };
   }
 
   export interface ObjectOfPathsAndPatterns {

diff --git a/packages/rule-tester/src/types/DependencyConstraint.ts b/packages/rule-tester/src/types/DependencyConstraint.ts
@@ -10,8 +10,8 @@ export interface SemverVersionConstraint {
   readonly range: string;
 }
 export type AtLeastVersionConstraint =
-  | `${number}.${number}.${number}`
   | `${number}.${number}.${number}-${string}`
+  | `${number}.${number}.${number}`
   | `${number}.${number}`
   | `${number}`;
 export type VersionConstraint =

diff --git a/packages/scope-manager/src/referencer/Referencer.ts b/packages/scope-manager/src/referencer/Referencer.ts
@@ -90,9 +90,7 @@ export class Referencer extends Visitor {
     }
   }
   public currentScope(): Scope;
-
   public currentScope(throwOnNull: true): Scope | null;
-
   public currentScope(dontThrowOnNull?: true): Scope | null {
     if (!dontThrowOnNull) {
       assert(this.scopeManager.currentScope, 'aaa');

diff --git a/packages/type-utils/src/isUnsafeAssignment.ts b/packages/type-utils/src/isUnsafeAssignment.ts
@@ -21,7 +21,7 @@ export function isUnsafeAssignment(
   receiver: ts.Type,
   checker: ts.TypeChecker,
   senderNode: TSESTree.Node | null,
-): { receiver: ts.Type; sender: ts.Type } | false {
+): false | { receiver: ts.Type; sender: ts.Type } {
   return isUnsafeAssignmentWorker(
     type,
     receiver,
@@ -37,7 +37,7 @@ function isUnsafeAssignmentWorker(
   checker: ts.TypeChecker,
   senderNode: TSESTree.Node | null,
   visited: Map<ts.Type, Set<ts.Type>>,
-): { receiver: ts.Type; sender: ts.Type } | false {
+): false | { receiver: ts.Type; sender: ts.Type } {
   if (isTypeAnyType(type)) {
     // Allow assignment of any ==> unknown.
     if (isTypeUnknownType(receiver)) {

diff --git a/packages/types/src/parser-options.ts b/packages/types/src/parser-options.ts
@@ -8,7 +8,6 @@ export type DebugLevel =
 export type CacheDurationSeconds = number | 'Infinity';
 
 export type EcmaVersion =
-  | 'latest'
   | 3
   | 5
   | 6
@@ -33,6 +32,7 @@ export type EcmaVersion =
   | 2023
   | 2024
   | 2025
+  | 'latest'
   | undefined;
 
 export type SourceTypeClassic = 'module' | 'script';

diff --git a/packages/utils/src/ts-eslint/Rule.ts b/packages/utils/src/ts-eslint/Rule.ts
@@ -766,11 +766,11 @@ export type AnyRuleModuleWithMetaDocs = RuleModuleWithMetaDocs<
  */
 export type LooseRuleDefinition =
   // TODO - remove RuleCreateFunction once we no longer support ESLint 8
+  | LooseRuleCreateFunction
   | {
       create: LooseRuleCreateFunction;
       meta?: object | undefined;
-    }
-  | LooseRuleCreateFunction;
+    };
 /*
 eslint-disable-next-line @typescript-eslint/no-explicit-any --
 intentionally using `any` to allow bi-directional assignment (unknown and

diff --git a/packages/utils/src/ts-eslint/SourceCode.ts b/packages/utils/src/ts-eslint/SourceCode.ts
@@ -416,6 +416,7 @@ namespace SourceCode {
 
   export type CursorWithSkipOptions =
     | number
+    | FilterPredicate
     | {
         /**
          * The predicate function to choose tokens.
@@ -429,11 +430,11 @@ namespace SourceCode {
          * The count of tokens the cursor skips.
          */
         skip?: number;
-      }
-    | FilterPredicate;
+      };
 
   export type CursorWithCountOptions =
     | number
+    | FilterPredicate
     | {
         /**
          * The maximum count of tokens the cursor iterates.
@@ -447,8 +448,7 @@ namespace SourceCode {
          * The flag to iterate comments as well.
          */
         includeComments?: boolean;
-      }
-    | FilterPredicate;
+      };
 }
 
 class SourceCode extends (ESLintSourceCode as typeof SourceCodeBase) {}

diff --git a/packages/website/src/components/layout/EditorTabs.tsx b/packages/website/src/components/layout/EditorTabs.tsx
@@ -10,7 +10,7 @@ export interface EditorTabsProps<T extends boolean | string> {
   readonly change: (name: T) => void;
   readonly showModal?: (name: T) => void;
   readonly showVisualEditor?: boolean;
-  readonly tabs: ({ label: string; value: T } | T)[];
+  readonly tabs: (T | { label: string; value: T })[];
 }
 
 function EditorTabs<T extends boolean | string>({

diff --git a/packages/website/src/theme/MDXComponents/index.tsx b/packages/website/src/theme/MDXComponents/index.tsx
@@ -1,5 +1,5 @@
-import Admonition from '@theme/Admonition';
 import MDXComponents from '@theme-original/MDXComponents';
+import Admonition from '@theme/Admonition';
 
 import { BaseRuleReference } from './BaseRuleReference';
 import { HiddenHeading } from './HiddenHeading';

diff --git a/packages/website/webpack.plugin.js b/packages/website/webpack.plugin.js
@@ -1,9 +1,9 @@
 // eslint-disable-next-line @typescript-eslint/no-require-imports
-const webpack = require('webpack');
+const CopyPlugin = require('copy-webpack-plugin');
 // eslint-disable-next-line @typescript-eslint/no-require-imports
 const path = require('node:path');
 // eslint-disable-next-line @typescript-eslint/no-require-imports
-const CopyPlugin = require('copy-webpack-plugin');
+const webpack = require('webpack');
 
 module.exports = function (/*context, options*/) {
   return {

diff --git a/tools/scripts/generate-contributors.mts b/tools/scripts/generate-contributors.mts
@@ -70,7 +70,7 @@ async function getData<T>(
 async function* fetchUsers(page = 1): AsyncIterableIterator<Contributor[]> {
   while (page <= MATCH_PAGE_NUMBER) {
     console.log(`Fetching page ${page} of contributors...`);
-    const contributors = await getData<{ message: string } | Contributor[]>(
+    const contributors = await getData<Contributor[] | { message: string }>(
       `${contributorsApiUrl}&page=${page}`,
     );