chore(eslint): migrate configuration to new flat config

Author: murdos

.eslintrc.js

@@ -9,11 +9,11 @@ jobs:
             - uses: actions/checkout@v4
             - uses: actions/setup-node@v4.4.0
               with:
-                node-version: 20
+                  node-version: 20
             - name: 'Install dependencies'
               run: npm install
             - name: 'Run linter'
-              run: ESLINT_USE_FLAT_CONFIG=false npm run lint
+              run: npm run lint
     auto-merge:
         name: 'dependabot-auto-merge'
         needs: linter

.github/workflows/checks.yml

@@ -0,0 +1,38 @@
+import { defineConfig } from 'eslint/config';
+import globals from 'globals';
+import js from '@eslint/js';
+import prettier from 'eslint-plugin-prettier/recommended';
+
+export default defineConfig([
+    js.configs.recommended,
+    prettier,
+    {
+        languageOptions: {
+            globals: {
+                ...globals.browser,
+                ...globals.greasemonkey,
+                ...globals.jquery,
+                LOGGER: true,
+                MBImportStyle: true,
+                MBImport: true,
+                MBLinks: true,
+                MBSearchItStyle: true,
+            },
+        },
+
+        rules: {
+            'prettier/prettier': 'error',
+            'prefer-template': 'error',
+            'no-console': 'off',
+            'no-inner-declarations': 'warn',
+            'no-global-assign': 'warn',
+            'no-redeclare': 'warn',
+            'no-self-assign': 'warn',
+            'no-undef': 'warn',
+            'no-useless-concat': 'warn',
+            'no-useless-escape': 'warn',
+            'no-unused-vars': 'warn',
+            'no-var': 'warn',
+        },
+    },
+]);

eslint.config.js

@@ -2,7 +2,7 @@
     "name": "musicbrainz-userscripts",
     "version": "1.0.0",
     "description": "Collection of userscripts for MusicBrainz",
-    "main": "index.js",
+    "type": "module",
     "directories": {
         "lib": "lib"
     },
@@ -31,10 +31,11 @@
     "homepage": "https://github.com/murdos/musicbrainz-userscripts#readme",
     "devDependencies": {
         "@eslint-community/eslint-utils": "^4.6.1",
+        "@eslint/js": "^9.25.1",
         "eslint": "^9.25.1",
-        "eslint-config-prettier": "^10.1.2",
         "eslint-plugin-import": "^2.31.0",
         "eslint-plugin-prettier": "^5.2.6",
+        "globals": "^16.0.0",
         "prettier": "^3.5.3"
     }
 }