index.js

/*
 * Copyright (c) 2017 American Express Travel Related Services Company, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

const forbiddenModules = [
  // want to restrict create-react-class usage within our modules
  'create-react-class',
  // want to prevent incorrect imports of moment
  { name: 'moment/moment', message: "Import only from 'moment' instead." },
];

module.exports = {
  parser: '@babel/eslint-parser',
  parserOptions: {
    ecmaVersion: 2020,
    sourceType: 'module',
    ecmaFeatures: {
      jsx: true,
    },
    requireConfigFile: false,
  },
  extends: [...[
    'eslint-config-airbnb',
    './unicorn',
  ].map(require.resolve),
  // aid maintainability of eslint directives (usually overrides)
  'plugin:eslint-comments/recommended',
  // Helpful rules for writing React
  'plugin:react/recommended',
  // Use native JS instead of lodash
  'plugin:you-dont-need-lodash-underscore/compatible',
  ],
  env: {
    browser: true,
    node: true,
    // we are using optional chaining and nullish coalescing
    es2020: true,
  },
  settings: {
    // the src folder can be used as the resource root for imports
    'import/resolver': {
      node: {
        paths: ['src'],
      },
    },
  },
  plugins: [
    'eslint-comments',
    'import',
    'inclusive-language',
    'jsx-a11y',
    'markdown',
    'react',
    'react-hooks',
    'you-dont-need-lodash-underscore',
  ],
  rules: {
    // open a PR per rule change

    // record why the directive is seen to be justified
    'eslint-comments/require-description': ['error'],
    // remove out of date directives, ensure the directive is used where it should be
    'eslint-comments/no-unused-disable': ['error'],

    // Simplifies code and reduces bugs
    // https://eslint.org/docs/rules/no-lonely-if
    'no-lonely-if': ['error'],

    // Reduces careless typo mistakes
    // https://eslint.org/docs/rules/no-return-assign
    'no-return-assign': ['error'],

    // Spreading is better than complex Object.assign
    // https://eslint.org/docs/rules/prefer-object-spread
    'prefer-object-spread': ['error'],

    // This catches typos that end up being bitwise operators
    // https://eslint.org/docs/rules/no-bitwise
    'no-bitwise': ['error'],

    // https://github.com/facebook/jsx/issues/23
    // The future is that props given with no value will work like object shorthand
    // notation instead of evaluating to true.
    // Currently our rules forbid adding a value of true, which will
    // add more refactoring for us in the future.
    // Requiring true to be set as the value will help future-proof our code.
    'react/jsx-boolean-value': ['error', 'always'],

    // Expand the acceptable boolean names to include
    // "is", "has", "can", "show" and "hide", as well as "show" and "hide" on their own
    // https://github.com/yannickcr/eslint-plugin-react/blob/v7.19.0/docs/rules/boolean-prop-naming.md
    'react/boolean-prop-naming': [
      'error',
      {
        propTypeNames: ['bool', 'mutuallyExclusiveTrueProps'],
        rule: '^((is|has|can|show|hide|should)[A-Z]([A-Za-z0-9]?)+|(show|hide))',
      },
    ],

    // don't require trailing commas for multi-line function calls
    // airbnb config assumes you're transpiling with https://npmjs.com/babel-preset-airbnb
    // which includes trailing function commas.
    // https://github.com/eslint/eslint/issues/7571#issuecomment-259538272
    // This makes life harder if you're linting bin files that aren't transpiled
    // or have the trailing function (ES2017 proposal) config set.
    // This is bad as that adds friction to linting all files, which is desired.
    'comma-dangle': ['error', {
      arrays: 'always-multiline',
      objects: 'always-multiline',
      imports: 'always-multiline',
      exports: 'always-multiline',
      functions: 'never',
    }],

    // airbnb defaults to a maximum cyclomatic complexity of 11
    complexity: ['error'],

    // This rule forces anchor tags to include an "href" attribute; however,
    // the Link component uses the "to" attribute instead. To prevent this
    // from causing linter errors, the below configuration specifies that
    // for Link components, the "to" attribute is also acceptable.
    'jsx-a11y/anchor-is-valid': ['error', {
      components: ['Link'],
      specialLink: ['to'],
    }],

    // This rule has been deprecated by jsx-a11y as of version 6.1.0
    // As we are past this version, and per the recommendations of the dev team,
    // we should turn this rule off.
    // https://github.com/evcohen/eslint-plugin-jsx-a11y/issues/455#issuecomment-403359963
    'jsx-a11y/label-has-for': 'off',

    // Nesting controls inside of label has poor support in assistive technologies,
    // instead enforce separate tags with an htmlFor on the label.
    // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/main/docs/rules/label-has-associated-control.md
    'jsx-a11y/label-has-associated-control': ['error', {
      assert: 'htmlFor',
    }],

    // this rule isn't ready yet
    // arrow functions are forced to put the return values on a new line, rather than inline
    // with the argument and fat arrow itself, which is awkward syntax
    // this rule, when "fixing" code will then cause problems with the max-length rule
    // https://github.com/airbnb/javascript/issues/1584#issuecomment-335676788
    'function-paren-newline': 'off',

    // restrict certain modules from being used
    'no-restricted-modules': ['error', { paths: forbiddenModules }],
    'no-restricted-imports': ['error', { paths: forbiddenModules }],

    // Functions that take many positional arguments can be difficult to work
    // with and produce less maintainable APIs. When more than three arguments
    // are needed, named arguments should be used.
    'max-params': ['error', 3],

    // When an anonymous function is the default export of a module, your stack traces
    // and performance profiles become littered with Anoynmous functions which aren't
    // helpful with debugging.
    'import/no-anonymous-default-export': ['error', {
      allowArray: true,
      allowLiteral: true,
      allowObject: true,
    }],

    // Don't enforce specific function type for components
    // https://github.com/yannickcr/eslint-plugin-react/blob/v7.19.0/docs/rules/function-component-definition.md
    'react/function-component-definition': 'off',

    // React hooks were introduced in 16.8.0 and have two restrictions that are addressed
    // with this rule:
    // 1. Hooks must be called from React functions
    // 2. Hooks can only be called from the top level and not within loops, conditions,
    // or nested functions
    // https://reactjs.org/docs/hooks-rules.html#eslint-plugin
    'react-hooks/rules-of-hooks': 'error',
    // https://github.com/facebook/react/issues/14920
    'react-hooks/exhaustive-deps': 'warn',

    // Forbid the use of extraneous packages
    'import/no-extraneous-dependencies': ['error', {
      devDependencies: [
        // base list from airbnb config
        'test/**', // tape, common npm pattern
        'tests/**', // also common npm pattern
        'spec/**', // mocha, rspec-like pattern
        '**/__tests__/**', // jest pattern
        '**/__mocks__/**', // jest pattern
        'test.{js,jsx}', // repos with a single test file
        'test-*.{js,jsx}', // repos with multiple top-level test files
        '**/*{.,_}{test,spec}.{js,jsx}', // tests where the extension or filename suffix denotes that it is a test
        '**/jest.config.js', // jest config
        '**/jest.setup.js', // jest setup
        '**/vue.config.js', // vue-cli config
        '**/webpack.config.js', // webpack config
        '**/webpack.config.*.js', // webpack config
        '**/rollup.config.js', // rollup config
        '**/rollup.config.*.js', // rollup config
        '**/gulpfile.js', // gulp config
        '**/gulpfile.*.js', // gulp config
        '**/Gruntfile{,.js}', // grunt config
        '**/protractor.conf.js', // protractor config
        '**/protractor.conf.*.js', // protractor config

        // additional paths used only in development
        'dev.*.js', // developer config
        'mock/**', // parrot mocks
      ],
      optionalDependencies: false,
    }],

    // File with one export should be no different than a file
    // with two  exports from the consumer side
    // https://github.com/benmosher/eslint-plugin-import/blob/v2.20.1/docs/rules/prefer-default-export.md
    'import/prefer-default-export': 'off',

    // React fragment syntax requires Babel 7.x but this preset needs to still support Babel 6.x
    'react/jsx-fragments': 'off',

    // This rule restricts the use of parentheses to only where they are necessary.
    'no-extra-parens': 'error',

    // Disabling this rule until this is resolved https://github.com/yannickcr/eslint-plugin-react/issues/1848
    // at the moment the fix makes the code look messy and at times unreadable
    'react/jsx-one-expression-per-line': 'off',

    // reduces the unnecessary boilerplate of explicitly setting props to `undefined`
    // prevent false-confidence for those less experienced with how default props work
    'react/require-default-props': 'off',

    // encourage the use of inclusive language
    /* eslint-disable inclusive-language/use-inclusive-words
    -- The following config lists noninclusive words: */
    'inclusive-language/use-inclusive-words': [
      'warn',
      {
        words: [
          {
            word: 'blacklist',
            suggestions: ['blocklist', 'denylist', 'deny', 'block', 'unapproved'],
          },
          {
            word: 'whitelist',
            suggestions: ['allowlist', 'passlist', 'allow', 'permit', 'approved'],
          },
          {
            word: 'master',
            suggestions: ['main', 'primary', 'host', 'leader'],
          },
          {
            word: 'slave',
            suggestions: ['secondary', 'replica', 'client', 'follower'],
          },
        ],
        lintStrings: true,
      },
    ],
    /* eslint-enable inclusive-language/use-inclusive-words -- Check for noninclusive words */

    // https://eslint.org/docs/rules/max-len
    'max-len': [
      // Options from airbnb https://github.com/airbnb/javascript/blob/d8cb404da74c302506f91e5928f30cc75109e74d/packages/eslint-config-airbnb-base/rules/style.js#L198-L205
      'error',
      100,
      2,
      {
        ignoreUrls: true,
        ignoreComments: false,
        ignoreRegExpLiterals: true,
        ignoreStrings: true,
        ignoreTemplateLiterals: true,
        // Options we want to override
        // Ignore comments that contain described eslint ignores, as these are often very long
        ignorePattern: '^\\s*// eslint-disable-next-line.*?--',
      },
    ],
  },
  overrides: [
    {
      // use the markdown processor for all .md files
      files: ['**/*.{md,mkdn,mdown,markdown}'],
      processor: 'markdown/markdown',
    },
    {
      // ```js -fenced code blocks inside .md files
      // Certain rules need to be disabled when we are linting markdown files,
      // since they will often be snippets in documentation that cannot be run on
      // their own.
      files: ['**/*.{md,mkdn,mdown,markdown}/*.{js,javascript,jsx,node}'],
      rules: {
        'no-unused-expressions': 0,
        'no-unused-vars': 0,
        'no-undef': 0,
        'react/jsx-no-undef': 0,
        'import/extensions': 0,
        'import/no-unresolved': 0,
        'import/prefer-default-export': 0,
        'import/no-extraneous-dependencies': 0,
        'react/react-in-jsx-scope': 0,
        'react/jsx-filename-extension': 0,
        'react/prop-types': 0,
        'react/require-default-props': 0,
      },
    },
    {
      files: ['**/*.jsx'],
      rules: {
        // It is common to comment JSX during normal development, so 'warn' is least disruptive
        // https://eslint.org/docs/rules/spaced-comment
        'spaced-comment': 'warn',
      },
    },
  ],
};