Upgrade deps and lint

eslint.config.mjs

@@ -0,0 +1,71 @@
+import mocha from 'eslint-plugin-mocha';
+import babel from '@babel/eslint-plugin';
+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: [
+        '**/.DS_Store',
+        '**/_sass',
+        '**/_site',
+        '**/coverage',
+        'dist/*',
+        '**/node_modules',
+        '**/package-lock.json',
+        'packages/*/dist/*',
+        '**/.env',
+        '**/.env.*',
+        '!**/.env.example',
+    ],
+}, ...compat.extends('eslint:recommended', 'plugin:mocha/recommended'), {
+    plugins: {
+        mocha,
+        '@babel': babel,
+    },
+
+    languageOptions: {
+        globals: {
+            ...globals.browser,
+            ...globals.node,
+            ...globals.jquery,
+            ...globals.amd,
+            ...globals.mocha,
+            __base: false,
+            expect: false,
+        },
+
+        parser: babelParser,
+        ecmaVersion: 6,
+        sourceType: 'module',
+
+        parserOptions: {
+            requireConfigFile: false,
+        },
+    },
+
+    rules: {
+        curly: 2,
+        eqeqeq: ['error', 'smart'],
+        quotes: [2, 'single', 'avoid-escape'],
+        semi: 2,
+
+        'no-unused-vars': ['error', {
+			caughtErrors: 'none',
+            varsIgnorePattern: 'should|expect',
+        }],
+
+        'mocha/no-mocha-arrows': 0,
+    },
+}];