Upgrade eslint to 9.x

eslint.config.mjs

@@ -0,0 +1,104 @@
+import eslint from '@eslint/js';
+import globals from 'globals';
+import stylistic from '@stylistic/eslint-plugin';
+import tseslint from 'typescript-eslint';
+
+export default tseslint.config(
+
+    // Base config
+    eslint.configs.recommended,
+    stylistic.configs['recommended-flat'],
+    ...tseslint.configs.strict,
+    ...tseslint.configs.stylistic,
+
+    {
+        rules: {
+
+            // Style
+            '@stylistic/array-bracket-spacing': [ 'error', 'always' ],
+            '@stylistic/arrow-parens': [ 'error', 'as-needed' ],
+            '@stylistic/indent': [ 'error', 4, { SwitchCase: 1 } ],
+            '@stylistic/indent-binary-ops': [ 'error', 4 ],
+            '@stylistic/linebreak-style': [ 'error', 'unix' ],
+            '@stylistic/max-statements-per-line': 'off',
+            '@stylistic/member-delimiter-style': [ 'error', { singleline: { delimiter: 'comma' }, multiline: { delimiter: 'comma' } } ],
+            '@stylistic/no-multiple-empty-lines': [ 'error', { max: 2 } ],
+            '@stylistic/operator-linebreak': 'off',
+            '@stylistic/padded-blocks': 'off',
+            '@stylistic/quotes': [ 'error', 'single' ],
+            '@stylistic/semi': [ 'error', 'always' ],
+
+            // Core rules (possible problems)
+            'no-constructor-return': 'error',
+            'no-duplicate-imports': 'error',
+            'no-self-compare': 'error',
+            'no-unmodified-loop-condition': 'error',
+
+            // Core rules (suggestions)
+            'camelcase': 'error',
+            'curly': 'error',
+            'eqeqeq': 'error',
+            'no-alert': 'error',
+            'no-console': 'error',
+            'no-eval': 'error',
+            'no-extend-native': 'error',
+            'no-implicit-coercion': 'error',
+            'no-implied-eval': 'error',
+            'no-invalid-this': 'error',
+            'no-labels': 'error',
+            'no-lone-blocks': 'error',
+            'no-new': 'error',
+            'no-new-func': 'error',
+            'no-new-wrappers': 'error',
+            'no-octal-escape': 'error',
+            'no-return-assign': [ 'error', 'always' ],
+            'no-throw-literal': 'error',
+            'no-useless-computed-key': 'error',
+            'no-useless-concat': 'error',
+            'no-useless-rename': 'error',
+            'no-useless-return': 'error',
+            'no-var': 'error',
+            'no-warning-comments': [ 'warn', { location: 'anywhere', terms: [ 'TODO' ] }],
+            'prefer-arrow-callback': 'error',
+            'prefer-const': 'error',
+            'prefer-regex-literals': 'error',
+            'prefer-rest-params': 'error',
+
+            // Typescript rules
+            '@typescript-eslint/consistent-type-definitions': 'off',
+            '@typescript-eslint/no-empty-function': [ 'error', { allow: [ 'private-constructors', 'protected-constructors' ] } ],
+            '@typescript-eslint/no-extraneous-class': [ 'error', { allowEmpty: true } ],
+            '@typescript-eslint/no-loop-func': 'error',
+            '@typescript-eslint/no-namespace': 'off',
+            '@typescript-eslint/no-non-null-assertion': 'off',
+            '@typescript-eslint/no-shadow': 'error',
+            '@typescript-eslint/unified-signatures': [ 'error', { ignoreDifferentlyNamedParameters: true } ],
+        },
+    },
+
+    {
+        files: [ 'demo/**' ],
+        languageOptions: {
+            globals: {
+                ...globals.node,
+            },
+        },
+        rules: {
+            'no-console': 'off',
+            '@typescript-eslint/no-require-imports': 'off',
+        },
+    },
+
+    {
+        files: [ 'test/**' ],
+        languageOptions: {
+            globals: {
+                ...globals.node,
+                ...globals.mocha,
+            },
+        },
+        rules: {
+            '@typescript-eslint/no-require-imports': 'off',
+        },
+    },
+);