use new config format

eslint.config.mjs

@@ -0,0 +1,59 @@
+import prettier from 'eslint-plugin-prettier'
+import globals from 'globals'
+import babelParser from '@babel/eslint-parser'
+import path from 'node:path'
+import { fileURLToPath } from 'node:url'
+import js from '@eslint/js'
+import { FlatCompat } from '@eslint/eslintrc'
+
+const __filename = fileURLToPath(import.meta.url)
+const __dirname = path.dirname(__filename)
+const compat = new FlatCompat({
+  baseDirectory: __dirname,
+  recommendedConfig: js.configs.recommended,
+  allConfig: js.configs.all,
+})
+
+export default [
+  {
+    ignores: ['**/node_modules', '**/package.json', '**/coverage'],
+  },
+  ...compat.extends('eslint:recommended', 'prettier'),
+  {
+    plugins: {
+      prettier,
+    },
+
+    languageOptions: {
+      globals: {
+        ...globals.node,
+      },
+
+      parser: babelParser,
+      ecmaVersion: 12,
+      sourceType: 'module',
+
+      parserOptions: {
+        requireConfigFile: false,
+      },
+    },
+
+    rules: {
+      'prettier/prettier': 'error',
+      'no-console': 2,
+    },
+  },
+  {
+    files: ['**/test/**/*.test.js'],
+
+    languageOptions: {
+      globals: {
+        ...globals.mocha,
+      },
+    },
+
+    rules: {
+      'prettier/prettier': 'error',
+    },
+  },
+]