eslint.config.mjs

import importPlugin from 'eslint-plugin-import'
import prettier from 'eslint-plugin-prettier'
import globals from 'globals'
import tseslint from 'typescript-eslint'

export default tseslint.config(
  // Global ignores
  {
    ignores: [
      '**/node_modules/**',
      '**/build/**',
      '**/dist/**',
      '**/.git/**',
      '**/.idea/**',
      '**/.husky/**',
    ],
  },

  // Main configuration
  {
    files: [
      '**/*.ts',
      '**/*.tsx',
      '**/*.js',
      '**/*.jsx',
      '**/*.mjs',
      '**/*.cjs',
      '**/*.mts',
    ],

    plugins: {
      '@typescript-eslint': tseslint.plugin,
      import: importPlugin,
      prettier: prettier,
    },

    linterOptions: {
      reportUnusedDisableDirectives: true,
    },

    languageOptions: {
      parser: tseslint.parser,
      globals: {
        ...globals.browser,
        ...globals.jest,
        ...globals.node,
      },

      ecmaVersion: 'latest',
      sourceType: 'module',

      parserOptions: {
        projectService: true,
        tsconfigRootDir: import.meta.dirname, // requires Node.js 20.11.0+
        allowDefaultProject: ['*.js', '*.mjs', '*.cjs'], // allow JS files to be parsed
      },
    },

    settings: {
      'import/resolver': {
        node: {
          extensions: ['.mjs', '.js', '.cjs', '.mts', '.ts', '.jsx', '.tsx'],
        },

        typescript: {
          alwaysTryTypes: true,
        },
      },
    },

    rules: {
      '@typescript-eslint/await-thenable': 'warn',
      '@typescript-eslint/consistent-type-imports': 'warn',
      '@typescript-eslint/no-misused-new': 'error',

      '@typescript-eslint/no-misused-promises': [
        'error',
        {
          checksConditionals: false,
          checksVoidReturn: false,
        },
      ],

      '@typescript-eslint/no-non-null-asserted-nullish-coalescing': 'error',
      '@typescript-eslint/no-unused-expressions': 'error',

      '@typescript-eslint/no-unused-vars': [
        'error',
        {
          args: 'after-used',
          argsIgnorePattern: '^_',
          ignoreRestSiblings: true,
        },
      ],

      '@typescript-eslint/prefer-as-const': 'warn',
      '@typescript-eslint/promise-function-async': 'warn',
      eqeqeq: ['error', 'always'],
      'no-unneeded-ternary': 'warn',
      'import/default': 'error',
      'import/export': 'error',
      'import/named': 'error',
      'import/no-cycle': 'error',
      'import/no-duplicates': 'error',
      'import/no-unresolved': 'error',
      'import/no-useless-path-segments': 'warn',

      'import/order': [
        'warn',
        {
          alphabetize: {
            caseInsensitive: true,
            order: 'asc',
          },

          groups: [
            'builtin',
            'external',
            'internal',
            'parent',
            'sibling',
            'index',
            'object',
          ],
          'newlines-between': 'always',
        },
      ],

      'no-constant-binary-expression': 'error',
      'no-constant-condition': 'error',
      'no-dupe-args': 'error',
      'no-dupe-keys': 'error',
      'no-empty-pattern': 'error',
      'no-extra-boolean-cast': 'error',
      'no-return-await': 'error',
      'no-unsafe-negation': 'warn',
      'no-unused-private-class-members': 'error',
      'prefer-const': 'warn',

      'prefer-promise-reject-errors': [
        'error',
        {
          allowEmptyReject: true,
        },
      ],

      'prettier/prettier': [
        'warn',
        {},
        {
          properties: {
            usePrettierrc: true,
          },
        },
      ],

      radix: 'error',

      'require-atomic-updates': [
        'error',
        {
          allowProperties: true,
        },
      ],

      'valid-typeof': 'warn',
    },
  },
  // For JavaScript files
  {
    files: [
      './**.js',
      './**.cjs',
      './**.mjs',
      '**/*.js',
      '**/*.cjs',
      '**/*.mjs',
      '**/*.jsx',
    ],

    // TODO: add more pragmatic rules for JavaScript files
    rules: {
      'no-undef': [
        'error',
        {
          typeof: false,
        },
      ],

      'no-redeclare': 'error',
    },
  },
)