ESLint configuration

app.js

const path = require('path');

module.exports = {
  parserOptions: {
    tsconfigRootDir: __dirname, // required for VS Code
    EXPERIMENTAL_useSourceOfProjectReferenceRedirect: true, // required for TS project references
  },
  extends: ['./frontend-app'], // or backend
  settings: {
    'import/resolver': {
      typescript: {
        project: [
          __dirname + '/tsconfig.json',
          // add more tsconfigs here if using TS project references
        ], // required for VS Code
      },
    },
  },
  rules: {
    'import/no-unused-modules': [
      'error',
      {
        src: [path.join(__dirname, 'src')],
        unusedExports: true,
        missingExports: true,
        ignoreExports: [
          // This is for Next.js app, replace with other roots if necessary
          // Stories and tests also go here
          __dirname + '/src/pages/**/*.tsx',
          __dirname + '/src/pages/**/*.ts',
        ],
      },
    ],
  },
};

backend.js

module.exports = {
  extends: [
    'eslint:recommended',
    'plugin:@typescript-eslint/recommended',
    'plugin:@typescript-eslint/recommended-requiring-type-checking',
    'plugin:import/typescript',
    'plugin:prettier/recommended',
    './shared',
  ],
  env: {
    es6: true,
    node: true,
  }
};

frontend.js

const restrictedGlobals = require('confusing-browser-globals');

module.exports = {
  plugins: ['react-hooks', 'react'],
  extends: [
    'eslint:recommended',
    'plugin:react/recommended',
    'plugin:react-hooks/recommended',
    'plugin:react/jsx-runtime',
    'plugin:@typescript-eslint/recommended',
    'plugin:@typescript-eslint/recommended-requiring-type-checking',
    'plugin:import/typescript',
    'plugin:jsx-a11y/recommended',
    'plugin:prettier/recommended',
    './shared',
  ],
  env: {
    browser: true,
    es6: true,
    node: true,
  },
  settings: {
    react: {
      version: 'detect',
    },
  },
  rules: {
    'no-restricted-globals': ['error'].concat(restrictedGlobals),
    'react-hooks/exhaustive-deps': 'error',
    'react-hooks/rules-of-hooks': 'error',
    'react/jsx-boolean-value': 'error',
    'react/jsx-filename-extension': ['error', { extensions: ['tsx'] }],
    'react/no-array-index-key': 'error',
    'react/prefer-stateless-function': 'error',
    'react/prop-types': 'off',
    'react/self-closing-comp': 'error',
  },
};

shared.js

module.exports = {
  root: true,
  parser: '@typescript-eslint/parser',
  parserOptions: {
    ecmaVersion: 2020,
    project: './tsconfig.json',
  },
  plugins: [
    '@typescript-eslint',
    'import',
    'no-type-assertion',
    'prettier',
    'sort-destructure-keys',
  ],
  settings: {
    'import/internal-regex': '^(src|shared)/',
    'import/resolver': {
      typescript: {
        alwaysTryTypes: true,
      },
    },
  },
  rules: {
    '@typescript-eslint/no-empty-function': 'off',
    '@typescript-eslint/no-explicit-any': 'error',
    '@typescript-eslint/restrict-template-expressions': [
      'error',
      { allowNumber: true },
    ],
    '@typescript-eslint/no-unnecessary-condition': 'error',
    '@typescript-eslint/no-unused-vars': [
      'error',
      { ignoreRestSiblings: true },
    ],
    '@typescript-eslint/no-use-before-define': [
      'error',
      { classes: false, functions: false },
    ],
    '@typescript-eslint/switch-exhaustiveness-check': 'error',
    'no-type-assertion/no-type-assertion': 'error',
    'import/no-anonymous-default-export': 'error',
    'import/no-cycle': 'error',
    'import/no-extraneous-dependencies': 'error',
    'import/order': [
      'error',
      {
        groups: [
          'builtin',
          'external',
          'internal',
          'parent',
          'sibling',
          'index',
        ],
        'newlines-between': 'always',
        alphabetize: { order: 'asc', caseInsensitive: true },
      },
    ],
    'no-console': ['error', { allow: ['warn', 'error', 'info'] }],
    'sort-destructure-keys/sort-destructure-keys': 'error',
    'sort-imports': [
      'error',
      {
        ignoreCase: true,
        ignoreDeclarationSort: true,
      },
    ],
  },
};