Update ESLint to v10.0.2

Author: artnc

.dockerignore

@@ -2,7 +2,7 @@
 !.clang-format
 !.editorconfig
 !entry.ts
-!eslint.config.js
+!eslint.config.mjs
 !ruff.toml
 !stylesheet.xml
 !svgo.config.js

.editorconfig

@@ -10,7 +10,7 @@ indent_style=tab
 indent_size=2
 max_line_length=100
 
-[*.{js,jsx,ts,tsx}]
+[*.{js,jsx,mjs,ts,tsx}]
 indent_size=2
 max_line_length=80
 

Dockerfile

@@ -58,24 +58,12 @@ echo 'source /black21-venv/bin/activate && black "$@"' > /usr/bin/black21
 chmod +x /usr/bin/black21
 
 # Install Node dependencies
-#
-# We stay on eslint-plugin-unicorn 56.0.1 because 57+ removed support for
-# importing this plugin into the ESLint config as CommonJS. (We use CommonJS
-# instead of ESM in the ESLint config mainly because the latter requires a new
-# local package.json file that declares `"type": "module"`, which interferes
-# with other tools like SVGO). I couldn't get the `deasync` hack to work - it
-# just hung forever. TODO: Try updating this plugin after updating Node.js to
-# v22+, which has experimental support for synchronously require()-ing ESM?
-# https://github.com/sindresorhus/eslint-plugin-unicorn/releases/tag/v57.0.0
-# https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c
-# https://nodejs.org/en/blog/announcements/v22-release-announce#support-requireing-synchronous-esm-graphs
-# https://github.com/eslint/eslint/issues/13684#issuecomment-722949152
 npm install -g \
   @prettier/plugin-xml@3.4.2 \
-  eslint@9.39.2 \
+  eslint@10.0.2 \
   eslint-plugin-jsdoc@62.7.1 \
-  eslint-plugin-sort-keys@2.3.5 \
-  eslint-plugin-unicorn@56.0.1 \
+  eslint-plugin-perfectionist@5.6.0 \
+  eslint-plugin-unicorn@63.0.0 \
   prettier@3.8.1 \
   svgo@4.0.1 \
   typescript-eslint@8.56.1
@@ -132,3 +120,5 @@ COPY --from=entry /entry.js /entry
 ENV COURSIER_CACHE=/tmp/coursier-cache
 ENV COURSIER_JVM_CACHE=/tmp/coursier-jvm-cache
 ENV NODE_PATH=/usr/local/lib/node_modules
+# .mjs import resolution doesn't respect NODE_PATH
+RUN ln -s /usr/local/lib/node_modules /node_modules

README.md

@@ -7,7 +7,7 @@ This repo contains [pre-commit](https://pre-commit.com/) hooks for Duolingo deve
 The main hook that runs several code formatters in parallel:
 
 - [Prettier](https://github.com/prettier/prettier) v3.8.1 for CSS, HTML, JS, JSX, Markdown, Sass, TypeScript, XML, YAML
-- [ESLint](https://eslint.org/) v9.39.2 for JS, TypeScript
+- [ESLint](https://eslint.org/) v10.0.2 for JS, TypeScript
 - [Ruff](https://docs.astral.sh/ruff/) v0.15.5 for Python 3
 - [Black](https://github.com/psf/black) v21.12b0 for Python 2
 - [autoflake](https://github.com/myint/autoflake) v1.7.8 for Python <!-- TODO: Upgrade to v2+, restrict to Python 2, and reenable Ruff rule F401 once our Python 3 repos that were converted from Python 2 no longer use type hint comments: https://github.com/PyCQA/autoflake/issues/222#issuecomment-1419089254 -->

entry.ts

@@ -183,7 +183,7 @@ const HOOKS: Record<HookName, Hook> = {
           "eslint",
           "--fix",
           "--config",
-          "/eslint.config.js",
+          "/eslint.config.mjs",
           ...sources,
         );
       } catch {
@@ -192,7 +192,7 @@ const HOOKS: Record<HookName, Hook> = {
       }
     },
     exclude: MINIFIED_JS_REGEX,
-    include: /\.[jt]sx?$/,
+    include: /\.(mjs|[jt]sx?)$/,
     runAfter: [HookName.Sed],
   },
   [HookName.Gofmt]: {
@@ -255,7 +255,7 @@ const HOOKS: Record<HookName, Hook> = {
   },
   [HookName.Prettier]: {
     action: sources => run("prettier", ...PRETTIER_OPTIONS, ...sources),
-    include: /\.(css|html?|markdown|md|scss|tsx?|ya?ml)$/,
+    include: /\.(css|html?|markdown|md|mjs|scss|tsx?|ya?ml)$/,
     runAfter: [HookName.Sed, HookName.EsLint],
   },
   [HookName.PrettierJs]: {
@@ -490,7 +490,11 @@ const HOOKS: Record<HookName, Hook> = {
 
 /** Files that match this pattern should never be processed */
 const GLOBAL_EXCLUDES = (() => {
-  const FOLDER_EXCLUDES = [".claude/skills/.generated", "build", "node_modules"];
+  const FOLDER_EXCLUDES = [
+    ".claude/skills/.generated",
+    "build",
+    "node_modules",
+  ];
   const FILE_EXCLUDES = [
     "AGENTS.md", // Generated by sync-ai-rules pre-commit hook
     "copilot-instructions.md", // Generated by sync-ai-rules pre-commit hook

eslint.config.js eslint.config.mjseslint.config.js renamed to eslint.config.mjs

@@ -1,11 +1,12 @@
-const { defineConfig } = require("eslint/config");
-const jsdoc = require("eslint-plugin-jsdoc");
-const sortKeys = require("eslint-plugin-sort-keys");
-const unicorn = require("eslint-plugin-unicorn");
-const tseslint = require("typescript-eslint");
+import { defineConfig } from "eslint/config";
+import perfectionist from "eslint-plugin-perfectionist";
+import { Alphabet } from "eslint-plugin-perfectionist/alphabet";
+import jsdoc from "eslint-plugin-jsdoc";
+import unicorn from "eslint-plugin-unicorn";
+import tseslint from "typescript-eslint";
 
 const config = {
-  files: ["**/*.{js,jsx,ts,tsx}"],
+  files: ["**/*.{js,jsx,mjs,ts,tsx}"],
   languageOptions: { parser: tseslint.parser },
   linterOptions: {
     // Individual repos may have their own additional ESLint setups that enable
@@ -19,7 +20,7 @@ const config = {
   plugins: {
     "@typescript-eslint": tseslint.plugin,
     jsdoc,
-    "sort-keys": sortKeys,
+    perfectionist,
     unicorn,
   },
   //
@@ -80,17 +81,7 @@ const config = {
     // "prefer-object-has-own": "error",
     // "prefer-object-spread": "error",
     "prefer-template": "error",
-    // This only sorts members within an individual import statement, not import
-    // statements ("declarations") themselves. We disable that because this
-    // rule sorts in a weird way: by first member rather than by module name.
-    // The `import/order` rule provided by eslint-plugin-import does sort
-    // declarations by module name, but we forgo that too because it groups
-    // declarations based on environmental factors (e.g. node_modules, Node
-    // version) that we can't easily determine or reproduce here in a
-    // repo-agnostic way. One compromise might be to use `import/order` and
-    // simply disable its regrouping feature in favor of whatever groups are
-    // found in the source code to be formatted, but no such option exists :/
-    "sort-imports": ["error", { ignoreDeclarationSort: true }],
+    // "sort-imports": "error", // Replaced by perfectionist/sort-imports and perfectionist/sort-named-imports
     "sort-vars": "error",
     // "strict": "error",
     // "unicode-bom": "error",
@@ -132,8 +123,28 @@ const config = {
     // "jsdoc/tag-lines": "error",
     // "jsdoc/text-escaping": "error",
 
-    // sort-keys rules. https://github.com/namnm/eslint-plugin-sort-keys
-    "sort-keys/sort-keys-fix": ["error", "asc", { natural: true }],
+    // perfectionist rules. https://perfectionist.dev/rules
+    // "perfectionist/sort-enums": "error", // Reordering can change numeric enum values
+    "perfectionist/sort-heritage-clauses": "error",
+    "perfectionist/sort-imports": [
+      "error",
+      {
+        groups: [], // Don't priorize type imports above value imports
+        newlinesBetween: "ignore",
+        newlinesInside: "ignore",
+      },
+    ],
+    "perfectionist/sort-interfaces": "error",
+    "perfectionist/sort-intersection-types": "error",
+    "perfectionist/sort-named-exports": "error",
+    "perfectionist/sort-named-imports": [
+      "error",
+      { partitionByNewLine: false },
+    ],
+    "perfectionist/sort-object-types": "error",
+    "perfectionist/sort-objects": "error",
+    // "perfectionist/sort-switch-case" // TODO: Enable once it supports partitionByNewLine
+    "perfectionist/sort-union-types": "error",
 
     // typescript-eslint rules. We exclude rules that require type info because
     // they're prohibitively slow. Get the list of autofixable rules by running
@@ -189,10 +200,9 @@ const config = {
     // "unicorn/new-for-builtins": "error",
     // "unicorn/no-array-for-each": "error", // Bug: fixer deletes comments
     // "unicorn/no-array-method-this-argument": "error",
-    // "unicorn/no-array-push-push": "error", // Bug: fixer deletes comments
     // "unicorn/no-await-expression-member": "error",
     "unicorn/no-console-spaces": "error",
-    // "unicorn/no-for-loop": "error", // Bug: https://github.com/sindresorhus/eslint-plugin-unicorn/issues/1802
+    "unicorn/no-for-loop": "error",
     // "unicorn/no-hex-escape": "error",
     // "unicorn/no-lonely-if": "error", // Bug: Moves comments around
     "unicorn/no-negated-condition": "error",
@@ -249,6 +259,7 @@ const config = {
     "unicorn/prefer-regexp-test": "error",
     // "unicorn/prefer-set-has": "error",
     "unicorn/prefer-set-size": "error",
+    // "unicorn/prefer-single-call": "error", // Bug: fixer deletes comments
     // "unicorn/prefer-spread": "error", // Bug: https://github.com/sindresorhus/eslint-plugin-unicorn/issues/2041
     // "unicorn/prefer-string-raw": "error",
     // "unicorn/prefer-string-replace-all": "error",
@@ -270,6 +281,22 @@ const config = {
 
     /* eslint-enable */
   },
+  settings: {
+    perfectionist: {
+      // By default, perfectionist sorts lowercase before uppercase. We reverse
+      // that behavior here to match our existing pre-2026 convention, which is
+      // also arguably more sensible from a coding perspective because it
+      // prioritizes SCREAMING_SNAKE_CASE constants, similar to how such
+      // constants are typically defined first in a source file
+      alphabet: Alphabet.generateRecommendedAlphabet()
+        .placeAllWithCaseBeforeAllWithOtherCase("uppercase")
+        .getCharacters(),
+      ignoreCase: false,
+      order: "asc",
+      partitionByNewLine: true,
+      type: "custom",
+    },
+  },
 };
 
-module.exports = defineConfig([config]);
+export default defineConfig([config]);

test/after/hello.ts

@@ -21,3 +21,31 @@ try {
     console.log("hi", `world${ex}`);
   }
 }
+
+interface Serializable {
+  serialize(): string;
+}
+interface Printable {
+  print(): void;
+}
+class Report implements Printable, Serializable {
+  print(): void {}
+  serialize(): string {
+    return "";
+  }
+}
+
+interface Options {
+  Cache: boolean;
+  Format: string;
+  debug: boolean;
+  verbose: boolean;
+}
+
+type Combined = Options & Printable & Serializable;
+
+type Level = "error" | "info" | "warn";
+
+type Point = { x: number; y: number };
+
+export type { Combined, Level, Options, Point };

test/before/hello.ts

@@ -1,6 +1,6 @@
 
-import   {  execSync , execFile }  from  "child_process"  ;
  import  {  writeFile,  FSWatcher, readFile  }  from  "fs" ;
+import   {  execSync , execFile }  from  "child_process"  ;
 
  import  {  foo  }  from "./bar";
 
@@ -25,3 +25,25 @@ try  {
   }catch( err)  {
 if  (8.00  > foo!!) console.log("hi ", "world" + err);
 }
+
+interface Serializable { serialize(): string }
+interface Printable { print(): void }
+class Report implements Serializable, Printable {
+  print(): void {}
+  serialize(): string { return "" }
+}
+
+interface Options {
+  verbose: boolean;
+  Format: string;
+  debug: boolean;
+  Cache: boolean;
+}
+
+type Combined = Printable & Options & Serializable;
+
+type Level = "warn" | "error" | "info";
+
+type Point = { y: number; x: number };
+
+export type { Options, Combined, Level, Point };