feat: eslint 9 support

eslint.config.mjs

@@ -0,0 +1,50 @@
+import { includeIgnoreFile } from '@eslint/compat';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+import eslint from '@eslint/js';
+import eslintPlugin from 'eslint-plugin-eslint-plugin';
+import eslintConfigPrettier from 'eslint-config-prettier';
+import tseslint from 'typescript-eslint';
+import globals from 'globals';
+import compat from './lib/esm/src/index.js';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+const gitignorePath = path.resolve(__dirname, '.gitignore');
+
+export default [
+  includeIgnoreFile(gitignorePath),
+  eslint.configs.recommended,
+  ...tseslint.configs.recommended,
+  eslintPlugin.configs['flat/recommended'],
+  compat.configs['flat/recommended'],
+  eslintConfigPrettier,
+  {
+    files: ["**/*.ts", "**/*.js", "**/*.mjs"],
+    rules: {
+      'no-template-curly-in-string': ['error'],
+      'no-console': ['warn']
+    },
+    languageOptions: {
+      globals: {
+        ...globals.jest,
+        ...globals.node
+      }
+    }
+  }
+];
+
+/*
+    parserOptions: {
+      project: './tsconfig.json'
+    },
+    "extends": [
+      "airbnb-typescript/base",
+      "plugin:import/typescript",
+    ],
+    "rules": {
+      "import/extensions": "off",
+      "import/no-extraneous-dependencies": "off"
+    },
+*/

package.json

@@ -45,9 +45,9 @@
   "scripts": {
     "benchmarks": "ts-node-transpile-only test/benchmarks.ts",
     "build": "rm -rf lib && tsc --project tsconfig.build.json && tsc --project tsconfig.esm.json",
-    "lint": "eslint --ignore-path .gitignore --ext .js,.ts .",
+    "lint": "eslint .",
     "spec": "jest --testPathIgnorePatterns test/e2e-repo.spec.ts /benchmarks-tmp",
-    "spec:e2e": "jest test/e2e-repo.spec.ts",
+    "spec:e2e": "jest --detectOpenHandles test/e2e-repo.spec.ts",
     "test": "npm run lint && npm run build && npm run spec",
     "tsc": "tsc",
     "version": "npm run build"
@@ -57,27 +57,6 @@
     "tabWidth": 2,
     "trailingComma": "es5"
   },
-  "eslintConfig": {
-    "env": {
-      "jest": true,
-      "node": true
-    },
-    "parser": "@typescript-eslint/parser",
-    "parserOptions": {
-      "project": "./tsconfig.json"
-    },
-    "extends": [
-      "airbnb-typescript/base",
-      "plugin:eslint-plugin/recommended",
-      "plugin:import/typescript",
-      "plugin:prettier/recommended"
-    ],
-    "rules": {
-      "import/extensions": "off",
-      "import/no-extraneous-dependencies": "off"
-    },
-    "root": true
-  },
   "jest": {
     "preset": "ts-jest",
     "testEnvironment": "node",
@@ -91,33 +70,30 @@
     "browserslist": "^4.23.0",
     "caniuse-lite": "^1.0.30001605",
     "find-up": "^5.0.0",
-    "globals": "^13.24.0",
+    "globals": "^15.7.0",
     "lodash.memoize": "^4.1.2",
     "semver": "^7.6.0"
   },
   "devDependencies": {
     "@babel/core": "^7.24.3",
     "@babel/eslint-parser": "^7.24.1",
+    "@eslint/compat": "^1.1.0",
+    "@eslint/js": "^9.6.0",
     "@semantic-release/changelog": "^6.0.3",
     "@semantic-release/git": "^10.0.1",
     "@tsconfig/node16": "^16.1.3",
     "@types/benchmark": "^2.1.5",
     "@types/caniuse-lite": "^1.0.5",
-    "@types/eslint": "^8.56.7",
+    "@types/eslint": "^8.56.10",
     "@types/jest": "^29.5.12",
     "@types/lodash.memoize": "^4.1.9",
     "@types/semver": "7.5.8",
-    "@typescript-eslint/eslint-plugin": "^7.5.0",
-    "@typescript-eslint/parser": "^7.5.0",
     "benchmark": "^2.1.4",
     "browserslist-config-erb": "^0.0.3",
     "electron": "^29.x.x",
-    "eslint": "^8.57.0",
-    "eslint-config-airbnb-typescript": "^18.0.0",
-    "eslint-config-bliss-typescript": "^6.0.2",
+    "eslint": "^9.6.0",
     "eslint-config-prettier": "^9.1.0",
-    "eslint-plugin-eslint-plugin": "^5.5.0",
-    "eslint-plugin-import": "^2.29.1",
+    "eslint-plugin-eslint-plugin": "^6.2.0",
     "eslint-plugin-prettier": "^5.1.3",
     "expect-type": "^0.19.0",
     "jest": "^29.7.0",
@@ -127,10 +103,10 @@
     "ts-jest": "^29.1.2",
     "ts-node": "^10.9.2",
     "typescript": "^5.4.3",
-    "typescript-eslint": "^7.5.0"
+    "typescript-eslint": "^8.0.0-alpha.36"
   },
   "peerDependencies": {
-    "eslint": "^4.0.0 || ^5.0.0 || ^6.0.0 || ^7.0.0 || ^8.0.0"
+    "eslint": "^4.0.0 || ^5.0.0 || ^6.0.0 || ^7.0.0 || ^8.0.0 || ^9.0.0"
   },
   "engines": {
     "node": ">=14.x"

src/helpers.ts

@@ -3,6 +3,7 @@ import browserslist from "browserslist";
 import {
   AstMetadataApiWithTargetsResolver,
   ESLintNode,
+  SourceCode,
   BrowserListConfig,
   Target,
   HandleFailingRule,
@@ -20,8 +21,12 @@ import { TargetNameMappings } from "./constants";
   - All of the rules have compatibility info attached to them
 - Each API is given to versioning.ts with compatibility info
 */
-function isInsideIfStatement(context: Context) {
-  return context.getAncestors().some((ancestor) => {
+function isInsideIfStatement(node: ESLintNode, sourceCode: SourceCode, context: Context) {
+  const ancestors = 'getAncestors' in sourceCode
+    // @ts-expect-error Fits
+    ? sourceCode?.getAncestors?.(node)
+    : context.getAncestors();
+  return ancestors?.some((ancestor) => {
     return ancestor.type === "IfStatement";
   });
 }
@@ -30,9 +35,10 @@ function checkNotInsideIfStatementAndReport(
   context: Context,
   handleFailingRule: HandleFailingRule,
   failingRule: AstMetadataApiWithTargetsResolver,
+  sourceCode: SourceCode,
   node: ESLintNode
 ) {
-  if (!isInsideIfStatement(context)) {
+  if (!isInsideIfStatement(node, sourceCode, context)) {
     handleFailingRule(failingRule, node);
   }
 }
@@ -41,6 +47,7 @@ export function lintCallExpression(
   context: Context,
   handleFailingRule: HandleFailingRule,
   rules: AstMetadataApiWithTargetsResolver[],
+  sourceCode: SourceCode,
   node: ESLintNode
 ) {
   if (!node.callee) return;
@@ -51,6 +58,7 @@ export function lintCallExpression(
       context,
       handleFailingRule,
       failingRule,
+      sourceCode,
       node
     );
 }
@@ -59,6 +67,7 @@ export function lintNewExpression(
   context: Context,
   handleFailingRule: HandleFailingRule,
   rules: Array<AstMetadataApiWithTargetsResolver>,
+  sourceCode: SourceCode,
   node: ESLintNode
 ) {
   if (!node.callee) return;
@@ -69,6 +78,7 @@ export function lintNewExpression(
       context,
       handleFailingRule,
       failingRule,
+      sourceCode,
       node
     );
 }
@@ -77,6 +87,7 @@ export function lintExpressionStatement(
   context: Context,
   handleFailingRule: HandleFailingRule,
   rules: AstMetadataApiWithTargetsResolver[],
+  sourceCode: SourceCode,
   node: ESLintNode
 ) {
   if (!node?.expression?.name) return;
@@ -88,6 +99,7 @@ export function lintExpressionStatement(
       context,
       handleFailingRule,
       failingRule,
+      sourceCode,
       node
     );
 }
@@ -119,6 +131,7 @@ export function lintMemberExpression(
   context: Context,
   handleFailingRule: HandleFailingRule,
   rules: Array<AstMetadataApiWithTargetsResolver>,
+  sourceCode: SourceCode,
   node: ESLintNode
 ) {
   if (!node.object || !node.property) return;
@@ -142,6 +155,7 @@ export function lintMemberExpression(
         context,
         handleFailingRule,
         failingRule,
+        sourceCode,
         node
       );
     }
@@ -158,6 +172,7 @@ export function lintMemberExpression(
         context,
         handleFailingRule,
         failingRule,
+        sourceCode,
         node
       );
   }

src/providers/mdn-provider.ts

@@ -73,7 +73,7 @@ export function isSupportedByMDN(
   node: AstMetadataApiWithTargetsResolver,
   { version, target: mdnTarget }: Target
 ): boolean {
-  // @ts-ignore
+  // @ts-expect-error Expected
   const target = reversedTargetMappings[mdnTarget];
   // If no record could be found, return true. Rules might not
   // be found because they could belong to another provider

src/rules/compat.ts

@@ -57,7 +57,7 @@ function generateErrorName(rule: AstMetadataApiWithTargetsResolver): string {
 }
 
 const getPolyfillSet = memoize(
-  (polyfillArrayJSON: string): Set<String> =>
+  (polyfillArrayJSON: string): Set<string> =>
     new Set(JSON.parse(polyfillArrayJSON))
 );
 
@@ -89,7 +89,7 @@ const babelConfigs = [
  * Determine if a user has a babel config, which we use to infer if the linted code is polyfilled.
  */
 function isUsingTranspiler(context: Context): boolean {
-  const dir = context.getFilename();
+  const dir = context.filename ?? context.getFilename();
   const configPath = findUp.sync(babelConfigs, {
     cwd: dir,
   });
@@ -150,6 +150,8 @@ export default {
     schema: [{ type: "string" }],
   },
   create(context: Context): ESLint {
+    const sourceCode = context.sourceCode ?? context.getSourceCode();
+
     // Determine lowest targets from browserslist config, which reads user's
     // package.json config section. Use config from eslintrc for testing purposes
     const browserslistConfig: BrowserListConfig =
@@ -162,6 +164,7 @@ export default {
       // @ts-expect-error Checking for accidental misspellings
       context.settings.browsersListOpts
     ) {
+      // eslint-disable-next-line -- CLI
       console.error(
         'Please ensure you spell `browserslistOpts` with a lowercase "l"!'
       );
@@ -217,19 +220,22 @@ export default {
         null,
         context,
         handleFailingRule,
-        targetedRules.CallExpression
+        targetedRules.CallExpression,
+        sourceCode
       ),
       NewExpression: lintNewExpression.bind(
         null,
         context,
         handleFailingRule,
-        targetedRules.NewExpression
+        targetedRules.NewExpression,
+        sourceCode
       ),
       ExpressionStatement: lintExpressionStatement.bind(
         null,
         context,
         handleFailingRule,
-        [...targetedRules.MemberExpression, ...targetedRules.CallExpression]
+        [...targetedRules.MemberExpression, ...targetedRules.CallExpression],
+        sourceCode
       ),
       MemberExpression: lintMemberExpression.bind(
         null,
@@ -239,7 +245,8 @@ export default {
           ...targetedRules.MemberExpression,
           ...targetedRules.CallExpression,
           ...targetedRules.NewExpression,
-        ]
+        ],
+        sourceCode
       ),
       // Keep track of all the defined variables. Do not report errors for nodes that are not defined
       Identifier(node: ESLintNode) {

src/types.ts

@@ -51,6 +51,8 @@ export type ESLintNode = {
   };
 };
 
+export type SourceCode = import('eslint').SourceCode;
+
 export interface AstMetadataApiWithTargetsResolver extends AstMetadataApi {
   id: string;
   caniuseId?: string;
@@ -70,6 +72,6 @@ export interface Context extends Rule.RuleContext {
     browserslistOpts?: BrowsersListOpts;
   };
 }
-
+// eslint-disable-next-line @typescript-eslint/no-empty-object-type
 export interface BrowsersListOpts
   extends Exclude<DefaultBrowsersListOpts, "path"> {}

test/benchmarks.ts

@@ -33,7 +33,7 @@ async function getBenchmark(repoInfo: RepoInfo) {
 
   const benchmark = new Benchmark(
     name,
-    (deferred: { resolve: Function }) => {
+    (deferred: { resolve: () => void }) => {
       eslint
         .lintFiles(repoInfo.filePatterns)
         .then(() => {
@@ -67,7 +67,7 @@ async function getBenchmark(repoInfo: RepoInfo) {
     name: "run",
     async: true,
     onStart: () => console.log("Starting benchmark suite"),
-    onComplete: (e) => {
+    onComplete: (e: Event & {currentTarget: Benchmark[]}) => {
       console.log("Finished benchmark suite");
       const reports = e.currentTarget.map((benchmark) => ({
         name: benchmark.name,

test/e2e.spec.ts

@@ -1,15 +1,17 @@
 import { RuleTester } from "eslint";
 import rule from "../src/rules/compat";
+import { parser } from 'typescript-eslint';
 
 const ruleTester = new RuleTester({
-  parserOptions: { ecmaVersion: 2020, sourceType: "module" },
-  parser: require.resolve("@typescript-eslint/parser"),
+  languageOptions: {
+    parser,
+    parserOptions: { ecmaVersion: 2020, sourceType: "module" },
+  },
   settings: {
     lintAllEsApis: true,
   },
 });
 
-// @ts-ignore
 ruleTester.run("compat", rule, {
   valid: [
     // Ignore ES APIs if config detected