Merge pull request #533 from abraham/copilot/update-eslint-to-v9

Migrate linting setup to ESLint v9 (flat config)

Author: abraham

eslint.config.js

@@ -0,0 +1,32 @@
+import { FlatCompat } from '@eslint/eslintrc';
+import js from '@eslint/js';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
+const compat = new FlatCompat({
+  baseDirectory: __dirname,
+  recommendedConfig: js.configs.recommended,
+});
+
+export default [
+  ...compat.config({
+    parser: '@typescript-eslint/parser',
+    parserOptions: {
+      ecmaVersion: 'latest',
+      sourceType: 'module',
+      project: './tsconfig.lint.json',
+    },
+    plugins: ['@typescript-eslint', 'jest'],
+    extends: [
+      'eslint:recommended',
+      'plugin:@typescript-eslint/eslint-recommended',
+      'plugin:@typescript-eslint/recommended',
+      'plugin:jest/recommended',
+      'plugin:import/errors',
+      'plugin:import/typescript',
+    ],
+  }),
+];

package.json

@@ -10,7 +10,7 @@
   "scripts": {
     "build": "tsc",
     "format": "prettier . --write",
-    "lint:eslint": "eslint src --ext .ts",
+    "lint:eslint": "eslint src",
     "lint:prettier": "prettier . --check",
     "lint": "npm run lint:eslint && npm run lint:prettier",
     "pkg-ok": "pkg-ok",
@@ -37,11 +37,12 @@
   },
   "homepage": "https://github.com/abraham/remotedata#readme",
   "devDependencies": {
+    "@eslint/eslintrc": "^3.0.0",
+    "@eslint/js": "^9.0.0",
     "@types/jest": "^30.0.0",
     "@typescript-eslint/eslint-plugin": "^8.0.0",
     "@typescript-eslint/parser": "^8.0.0",
-    "eslint": "^8.0.0",
-    "eslint-plugin-deprecation": "^3.0.0",
+    "eslint": "^9.0.0",
     "eslint-plugin-import": "^2.0.0",
     "eslint-plugin-jest": "^29.0.1",
     "jest": "^30.0.3",
@@ -78,28 +79,6 @@
       "node"
     ]
   },
-  "eslintConfig": {
-    "root": true,
-    "parser": "@typescript-eslint/parser",
-    "parserOptions": {
-      "ecmaVersion": "latest",
-      "sourceType": "module",
-      "project": "./tsconfig.lint.json"
-    },
-    "plugins": [
-      "@typescript-eslint",
-      "jest"
-    ],
-    "extends": [
-      "eslint:recommended",
-      "plugin:@typescript-eslint/eslint-recommended",
-      "plugin:@typescript-eslint/recommended",
-      "plugin:jest/recommended",
-      "plugin:import/errors",
-      "plugin:import/typescript",
-      "plugin:deprecation/recommended"
-    ]
-  },
   "prettier": {
     "singleQuote": true,
     "trailingComma": "all"