Migrate ESLint to new config file format

.github/workflows/lint.yml

@@ -10,4 +10,7 @@ jobs:
       - uses: actions/setup-node@v3
         with:
           node-version: 18
+      - run: npm install globals
+      - run: npm install @eslint/eslintrc
+      - run: npm install @eslint/js
       - run: npx eslint .

.pre-commit-config.yaml

@@ -0,0 +1,5 @@
+repos:
+    - repo: https://github.com/pre-commit/mirrors-eslint
+      rev: v9.6.0
+      hooks:
+            -   id: eslint

eslint.config.mjs

@@ -0,0 +1,28 @@
+import globals from "globals";
+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 [...compat.extends("eslint:recommended"), {
+    languageOptions: {
+        globals: {
+            ...globals.browser,
+        },
+
+        ecmaVersion: "latest",
+        sourceType: "module",
+    },
+
+    rules: {
+        "no-unused-vars": 0,
+    },
+}];