.eslintrc.js

const confusingBrowserGlobals = require('confusing-browser-globals');
const path = require('path');

module.exports = {
  root: true, // So parent files don't get applied
  globals: {
    preval: false, // Used in the documentation
  },
  env: {
    es6: true,
    browser: true,
    node: true,
  },
  extends: ['plugin:import/recommended', 'airbnb', 'prettier', 'prettier/react'],
  parser: 'babel-eslint',
  parserOptions: {
    ecmaVersion: 7,
    sourceType: 'module',
  },
  plugins: ['babel', 'material-ui', 'react-hooks'],
  settings: {
    'import/resolver': {
      webpack: {
        config: path.join(__dirname, './docs/webpackBaseConfig.js'),
      },
    },
  },
  /**
   * Sorted alphanumerically within each group. built-in and each plugin form
   * their own groups.
   */
  rules: {
    'consistent-this': ['error', 'self'],
    'linebreak-style': 'off', // Doesn't play nicely with Windows
    // just as bad as "max components per file"
    'max-classes-per-file': 'off',
    'no-alert': 'error',
    // Strict, airbnb is using warn; allow warn and error for dev environments
    'no-console': ['error', { allow: ['warn', 'error'] }],
    'no-constant-condition': 'error',
    // Airbnb use error
    'no-param-reassign': 'off',
    'no-prototype-builtins': 'off',
    'no-restricted-imports': [
      'error',
      {
        patterns: ['@material-ui/*/*/*', '!@material-ui/core/test-utils/*'],
      },
    ],
    'nonblock-statement-body-position': 'error',
    // Airbnb restricts isNaN and isFinite which are necessary for IE 11
    // we have to be disciplined about the usage and ensure the Number type for its
    // arguments
    'no-restricted-globals': ['error'].concat(confusingBrowserGlobals),
    'no-underscore-dangle': 'error',
    'prefer-arrow-callback': ['error', { allowNamedFunctions: true }],
    'prefer-destructuring': 'off', // Destructuring harm grep potential.

    'jsx-a11y/label-has-associated-control': 'off',
    'jsx-a11y/label-has-for': 'off', // deprecated
    'jsx-a11y/no-autofocus': 'off', // We are a library, people do what they want.

    'material-ui/docgen-ignore-before-comment': 'error',

    // This rule is great for raising people awareness of what a key is and how it works.
    'react/no-array-index-key': 'off',
    'react/destructuring-assignment': 'off',
    // It's buggy
    'react/forbid-prop-types': 'off',
    'react/jsx-curly-brace-presence': 'off',
    // prefer <React.Fragment> over <>. The former allows `key` while the latter doesn't
    'react/jsx-fragments': ['error', 'element'],
    'react/jsx-filename-extension': ['error', { extensions: ['.js'] }], // airbnb is using .jsx
    'react/jsx-handler-names': [
      'error',
      {
        // airbnb is disabling this rule
        eventHandlerPrefix: 'handle',
        eventHandlerPropPrefix: 'on',
      },
    ],
    // not a good rule for components close to the DOM
    'react/jsx-props-no-spreading': 'off',
    'react/no-danger': 'error',
    // Strict, airbnb is using off
    'react/no-direct-mutation-state': 'error',
    'react/no-find-dom-node': 'off',
    'react/no-multi-comp': 'off',
    'react/require-default-props': 'off',
    'react/sort-prop-types': 'error',
    // This depends entirely on what you're doing. There's no universal pattern
    'react/state-in-constructor': 'off',
    // stylistic opinion. For conditional assignment we want it outside, otherwise as static
    'react/static-property-placement': 'off',

    'import/no-extraneous-dependencies': 'off', // It would be better to enable this rule.
    'import/namespace': ['error', { allowComputed: true }],
    'import/order': [
      'error',
      {
        groups: [['index', 'sibling', 'parent', 'internal', 'external', 'builtin']],
        'newlines-between': 'never',
      },
    ],

    'react-hooks/rules-of-hooks': 'error',
    'react-hooks/exhaustive-deps': ['error', { additionalHooks: 'useEnhancedEffect' }],
  },
  overrides: [
    {
      files: [
        '**/test-utils/**/*.js',
        // matching the pattern of the test runner
        '*.test.js',
      ],
      env: {
        mocha: true,
      },
      extends: ['plugin:mocha/recommended'],
      rules: {
        // does not work with wildcard imports. Mistakes will throw at runtime anyway
        'import/named': 'off',
        //
        'no-restricted-imports': [
          'error',
          {
            paths: [
              {
                name: '@material-ui/core/test-utils',
                importNames: ['createMount'],
                message:
                  "Please use `import createMount from 'test/utils/createMount'` instead. `createMount` from /core has cleanup issues that require breaking changes.",
              },
            ],
          },
        ],

        'material-ui/disallow-active-element-as-key-event-target': 'error',

        // upgraded level from recommended
        'mocha/no-exclusive-tests': 'error',
        'mocha/no-skipped-tests': 'error',

        // no rationale provided in /recommended
        'mocha/no-mocha-arrows': 'off',
        // definitely a useful rule but too many false positives
        // due to `describeConformance`
        // "If you're using dynamically generated tests, you should disable this rule.""
        'mocha/no-setup-in-describe': 'off',
        // `beforeEach` for a single case is optimized for change
        // when we add a test we don't have to refactor the existing
        // test to `beforeEach`.
        // `beforeEach`+`afterEach` also means that the `beforeEach`
        // is cleaned up in `afterEach` if the test causes a crash
        'mocha/no-hooks-for-single-case': 'off',

        // disable eslint-plugin-jsx-a11y
        // tests are not driven by assistive technology
        // add `jsx-a11y` rules once you encounter them in tests
        'jsx-a11y/click-events-have-key-events': 'off',
        'jsx-a11y/control-has-associated-label': 'off',
        'jsx-a11y/iframe-has-title': 'off',
        'jsx-a11y/mouse-events-have-key-events': 'off',
        'jsx-a11y/no-noninteractive-tabindex': 'off',
        'jsx-a11y/no-static-element-interactions': 'off',
        'jsx-a11y/tabindex-no-positive': 'off',

        // They are accessed to test custom validator implementation with PropTypes.checkPropTypes
        'react/forbid-foreign-prop-types': 'off',
        // components that are defined in test are isolated enough
        // that they don't need type-checking
        'react/prop-types': 'off',
      },
    },
    {
      files: ['docs/src/modules/components/**/*.js'],
      rules: {
        'material-ui/no-hardcoded-labels': [
          'error',
          { allow: ['Material-UI', 'Twitter', 'GitHub', 'StackOverflow'] },
        ],
      },
    },
    {
      files: ['docs/pages/**/*.js'],
      rules: {
        'react/prop-types': 'off',
      },
    },
  ],
};