Use ESLint

.eslintrc.js

@@ -0,0 +1,39 @@
+module.exports = {
+  env: {
+    node: true,
+    es2022: true,
+    browser: true,
+  },
+  extends: ['eslint:recommended', 'plugin:astro/recommended'],
+  parserOptions: {
+    ecmaVersion: 'latest',
+    sourceType: 'module',
+  },
+  rules: {},
+  overrides: [
+    {
+      files: ['*.astro'],
+      parser: 'astro-eslint-parser',
+      parserOptions: {
+        parser: '@typescript-eslint/parser',
+        extraFileExtensions: ['.astro'],
+      },
+      rules: {},
+    },
+    {
+      files: ['*.ts'],
+      parser: '@typescript-eslint/parser',
+      extends: ['plugin:@typescript-eslint/recommended'],
+      rules: {
+        '@typescript-eslint/no-unused-vars': ['error', { argsIgnorePattern: '^_', destructuredArrayIgnorePattern: '^_' }],
+        '@typescript-eslint/no-non-null-assertion': 'off',
+      },
+    },
+    {
+      // Define the configuration for `<script>` tag.
+      // Script in `<script>` is assigned a virtual file name with the `.js` extension.
+      files: ['**/*.astro/*.js', '*.astro/*.js'],
+      parser: '@typescript-eslint/parser',
+    },
+  ],
+};