refactor: migrate ESLint to version 9 with a flat configuration

Author: mrholek

.eslintrc.js

@@ -0,0 +1,39 @@
+import eslintPluginPrettierRecommended from 'eslint-plugin-prettier/recommended'
+import eslintPluginReact from 'eslint-plugin-react'
+import eslintPluginReactHooks from 'eslint-plugin-react-hooks'
+import globals from 'globals'
+
+export default [
+  { ignores: ['eslint.config.mjs'] },
+  {
+    ...eslintPluginReact.configs.flat.recommended,
+    ...eslintPluginReact.configs.flat['jsx-runtime'],
+    files: ['src/**/*.{js,jsx}'],
+    plugins: {
+      eslintPluginReact,
+      'react-hooks': eslintPluginReactHooks,
+    },
+    languageOptions: {
+      globals: {
+        ...globals.browser,
+        ...globals.node,
+      },
+      ecmaVersion: 'latest',
+      sourceType: 'module',
+      parserOptions: {
+        ecmaFeatures: {
+          jsx: true,
+        },
+      },
+    },
+    settings: {
+      react: {
+        version: 'detect',
+      },
+    },
+    rules: {
+      ...eslintPluginReactHooks.configs.recommended.rules,
+    },
+  },
+  eslintPluginPrettierRecommended,
+]

eslint.config.mjs

@@ -14,7 +14,7 @@
   "author": "The CoreUI Team (https://github.com/orgs/coreui/people)",
   "scripts": {
     "build": "vite build",
-    "lint": "eslint \"src/**/*.js\"",
+    "lint": "eslint",
     "serve": "vite preview",
     "start": "vite"
   },
@@ -41,11 +41,12 @@
   "devDependencies": {
     "@vitejs/plugin-react": "^4.3.3",
     "autoprefixer": "^10.4.20",
-    "eslint": "^8.57.0",
-    "eslint-config-prettier": "^9.1.0",
-    "eslint-plugin-prettier": "^5.2.1",
-    "eslint-plugin-react": "^7.37.2",
-    "eslint-plugin-react-hooks": "^4.6.2",
+    "eslint": "^9.19.0",
+    "eslint-config-prettier": "^10.0.1",
+    "eslint-plugin-prettier": "^5.2.3",
+    "eslint-plugin-react": "^7.37.4",
+    "eslint-plugin-react-hooks": "^5.1.0",
+    "globals": "^15.14.0",
     "postcss": "^8.4.49",
     "prettier": "3.3.3",
     "sass": "^1.81.0",