.eslintrc.js

/**
 * Copyright 2018-present Facebook.
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 * @format
 */

const fbjs = require('eslint-config-fbjs');

// enforces copyright header and @format directive to be present in every file
const pattern = /^\*\n \* Copyright 20\d{2}-present Facebook\.\n \* This source code is licensed under the MIT license found in the\n \* LICENSE file in the root directory of this source tree\.\n \* @format\n./;

const prettierConfig = {
  requirePragma: true,
  singleQuote: true,
  trailingComma: 'all',
  bracketSpacing: false,
  jsxBracketSameLine: true,
  parser: 'flow',
};

module.exports = {
  parser: 'babel-eslint',
  extends: 'fbjs',
  plugins: [...fbjs.plugins, 'header', 'prettier', '@typescript-eslint'],
  rules: {
    // disable rules from eslint-config-fbjs
    'react/react-in-jsx-scope': 0, // not needed with our metro implementation
    'no-new': 0, // new keyword needed e.g. new Notification
    'no-catch-shadow': 0, // only relevant for IE8 and below
    'no-bitwise': 0, // bitwise operations needed in some places
    'consistent-return': 0,
    'no-var': 2,
    'prefer-const': [2, {destructuring: 'all'}],
    'prefer-spread': 1,
    'prefer-rest-params': 1,
    'max-len': 0, // lets prettier take care of this
    indent: 0, // lets prettier take care of this
    'no-console': 0, // we're setting window.console in App.js
    'no-multi-spaces': 2,
    'prefer-promise-reject-errors': 1,
    'no-throw-literal': 'error',
    'no-extra-boolean-cast': 2,
    'no-extra-semi': 2,
    'no-unsafe-negation': 2,
    'no-useless-computed-key': 2,
    'no-useless-rename': 2,

    // additional rules for this project
    'header/header': [2, 'block', {pattern}],
    'prettier/prettier': [2, prettierConfig],
    'flowtype/object-type-delimiter': [0],
  },
  overrides: [
    {
      files: ['*.tsx'],
      parser: '@typescript-eslint/parser',
      rules: {
        'prettier/prettier': [2, {...prettierConfig, parser: 'typescript'}],
        '@typescript-eslint/no-unused-vars': [1, {argsIgnorePattern: '^_'}],
      },
    },
  ],
};