Update ESLint to v9.x (#269)

Author: XhmikosR

.eslintrc.json

@@ -0,0 +1,64 @@
+import js from '@eslint/js'
+import globals from 'globals'
+
+/** @type {import('eslint').Linter.RulesRecord} */
+const RULES = {
+  'comma-dangle': [
+    'error',
+    'never'
+  ],
+  'quotes': [
+    'error',
+    'single'
+  ],
+  'quote-props': [
+    'error',
+    'always'
+  ]
+};
+
+/** @type {import('eslint').Linter.FlatConfig[]} */
+export default [
+  // global ignores
+  {
+    'ignores': [
+      'bootstrap',
+      'node_modules/**'
+    ]
+  },
+  {
+    'languageOptions': {
+      'ecmaVersion': 2022,
+      'sourceType': 'script',
+      'globals': {
+        ...globals.node
+      }
+    },
+    'linterOptions': {
+      'reportUnusedDisableDirectives': 'error'
+    }
+  },
+  js.configs.recommended,
+  {
+    'files': [
+      '**/*.js'
+    ],
+    'rules': {
+      ...RULES
+    }
+  },
+  {
+    'files': [
+      '**/*.mjs'
+    ],
+    'languageOptions': {
+      'sourceType': 'module',
+      'globals': {
+        ...globals.nodeBuiltin
+      }
+    },
+    'rules': {
+      ...RULES
+    }
+  }
+]