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| 1 | +/** We extend a variety of already-configured ESLint rules (see `extends` in the exported ESLint |
| 2 | + * config below). Note that plugins (see `plugins`) simply give us access to rules. We can extend |
| 3 | + * rules from those plugins, if an exported configuration is available, or we can customize |
| 4 | + * individual rules ourselves (see `customRules`). We can also extend rules and then override some |
| 5 | + * of them (see `airbnbOverrides`). To inspect a configured rule that we're extending, simply go to |
| 6 | + * the package repository and search for the rule name (e.g. https://github.com/airbnb/javascript/search?q=arrow-parens). |
| 7 | + */ |
| 8 | + |
| 9 | +// Rules that override the airbnb configuration that we extend. |
| 10 | +const airbnbOverrides = { |
| 11 | + // Files.com: Brevity. |
| 12 | + // Airbnb: Consistency. Diff churn. Inconvenience of adding/removing parens as code changes. |
| 13 | + 'arrow-parens': ['error', 'as-needed'], |
| 14 | + |
| 15 | + // Files.com: Consistency. Diff churn. Inconvenience of adding/removing braces as code changes. |
| 16 | + // Airbnb: Brevity (only require curly braces for multi-line statements, allowing for single-line |
| 17 | + // `if` statements with no braces, for example). |
| 18 | + curly: ['error', 'all'], |
| 19 | + |
| 20 | + // Airbnb: Enforces strict equality with the exception of loose equality checks on null (which is |
| 21 | + // an easy way to check for either null or undefined). See |
| 22 | + // https://github.com/airbnb/javascript/issues/1473#issuecomment-312178468. |
| 23 | + // Files.com: No exceptions to strict equality. For a check of either null or undefined, prefer |
| 24 | + // isNil() from lodash which does a loose equality check under the hood, but demonstrates explicit |
| 25 | + // intent when used in our codebase. |
| 26 | + eqeqeq: ['error', 'always'], |
| 27 | + |
| 28 | + // Function names allow for a better debugging experience (i.e. eliminates anonymous function |
| 29 | + // exceptions). Airbnb has this set to warn, and they recommend always naming functions (in order |
| 30 | + // to eliminate any assumptions made about the Error's call stack). However, in our case, the name |
| 31 | + // is inferred from the containing variable (modern browsers already handle this, as do compilers |
| 32 | + // such as Babel, which we use). Therefore, we can use the 'as-needed' option and only require a |
| 33 | + // name when it isn't assigned automatically per the ECMAScript specification. |
| 34 | + 'func-names': ['error', 'as-needed'], |
| 35 | + |
| 36 | + // Enforced by Airbnb style guide, but not yet enforced via Airbnb's lint rules. This is on |
| 37 | + // Airbnb's TODO list, but we'll go ahead and enforce it now. We can remove override after they |
| 38 | + // enforce expression with an error. |
| 39 | + 'func-style': ['error', 'expression'], |
| 40 | + |
| 41 | + // Airbnb: warn |
| 42 | + 'no-console': 'error', |
| 43 | + |
| 44 | + // Airbnb: off |
| 45 | + 'padding-line-between-statements': [ |
| 46 | + 'error', |
| 47 | + { |
| 48 | + blankLine: 'always', |
| 49 | + next: '*', |
| 50 | + prev: [ |
| 51 | + 'block', |
| 52 | + 'block-like', |
| 53 | + 'multiline-block-like', |
| 54 | + 'multiline-const', |
| 55 | + 'multiline-expression', |
| 56 | + 'multiline-let', |
| 57 | + ], |
| 58 | + }, |
| 59 | + ], |
| 60 | + |
| 61 | + // Files.com: Brevity. |
| 62 | + // Airbnb: Rare code-safety concerns that may grow with new editions of ECMAScript. |
| 63 | + semi: ['error', 'never'], |
| 64 | + |
| 65 | + // Airbnb has this configured, but disabled. We enable it with their configuration, given that |
| 66 | + // Files.com prefers alphabetization. Also see the 'react/jsx-sort-props' and |
| 67 | + // sort-destructure-keys rules. |
| 68 | + 'sort-keys': ['error', 'asc', { caseSensitive: false, natural: true }], |
| 69 | +} |
| 70 | + |
| 71 | +// Temporary overrides of our extended configurations, until we've either cleaned up all errors or |
| 72 | +// make a decision to permanently override a rule. To clean up, remove rule (allowing the extended |
| 73 | +// style guide to take over), run lint, and fix errors. |
| 74 | +const temporaryOverrides = { |
| 75 | + camelcase: ['warn', { ignoreDestructuring: false, properties: 'never' }], |
| 76 | + 'consistent-return': 'warn', |
| 77 | + 'global-require': 'off', |
| 78 | + 'guard-for-in': 'warn', |
| 79 | + 'implicit-arrow-linebreak': 'off', |
| 80 | + 'import/no-dynamic-require': 'warn', |
| 81 | + 'import/no-import-module-exports': 'off', |
| 82 | + 'import/no-named-as-default': 'warn', |
| 83 | + 'import/prefer-default-export': 'warn', |
| 84 | + 'jest/no-conditional-expect': 'warn', |
| 85 | + 'jsx-a11y/label-has-associated-control': ['warn', { |
| 86 | + assert: 'either', |
| 87 | + controlComponents: ['Input', 'Field'], |
| 88 | + depth: 25, |
| 89 | + labelAttributes: [], |
| 90 | + labelComponents: [], |
| 91 | + }], |
| 92 | + 'jsx-a11y/no-autofocus': ['warn', { ignoreNonDOM: true }], |
| 93 | + 'max-len': "off", |
| 94 | + 'no-await-in-loop': 'warn', |
| 95 | + 'no-confusing-arrow': ['warn', { allowParens: true }], |
| 96 | + 'no-continue': 'warn', |
| 97 | + 'no-empty-function': ['warn', { |
| 98 | + allow: [ |
| 99 | + 'arrowFunctions', |
| 100 | + 'functions', |
| 101 | + 'methods', |
| 102 | + ], |
| 103 | + }], |
| 104 | + 'no-nested-ternary': 'off', |
| 105 | + 'no-param-reassign': 'off', |
| 106 | + 'no-plusplus': 'off', |
| 107 | + 'no-promise-executor-return': 'warn', |
| 108 | + 'no-restricted-exports': ['warn', { restrictedNamedExports: ['default', 'then'] }], |
| 109 | + 'no-restricted-syntax': [ |
| 110 | + 'warn', |
| 111 | + { |
| 112 | + message: 'for..in loops iterate over the entire prototype chain, which is virtually never what you want. Use Object.{keys,values,entries}, and iterate over the resulting array.', |
| 113 | + selector: 'ForInStatement', |
| 114 | + }, |
| 115 | + { |
| 116 | + message: 'iterators/generators require regenerator-runtime, which is too heavyweight for this guide to allow them. Separately, loops should be avoided in favor of array iterations.', |
| 117 | + selector: 'ForOfStatement', |
| 118 | + }, |
| 119 | + { |
| 120 | + message: 'Labels are a form of GOTO; using them makes code confusing and hard to maintain and understand.', |
| 121 | + selector: 'LabeledStatement', |
| 122 | + }, |
| 123 | + { |
| 124 | + message: '`with` is disallowed in strict mode because it makes code impossible to predict and optimize.', |
| 125 | + selector: 'WithStatement', |
| 126 | + }, |
| 127 | + ], |
| 128 | + 'no-return-await': 'warn', |
| 129 | + 'no-shadow': 'warn', |
| 130 | + 'no-underscore-dangle': 'off', |
| 131 | + 'import/extensions': 'off', |
| 132 | + radix: 'warn', |
| 133 | +} |
| 134 | + |
| 135 | +module.exports = { |
| 136 | + env: { |
| 137 | + browser: true, |
| 138 | + es2021: true, |
| 139 | + node: true, |
| 140 | + }, |
| 141 | + extends: [ |
| 142 | + // Rule names without prefixes (standard ESLint rules), and those prefixed with jsx-a11y/, |
| 143 | + // react/, and import/ |
| 144 | + 'airbnb', |
| 145 | + |
| 146 | + // Rule names prefixed with react-hooks/ |
| 147 | + 'airbnb/hooks', |
| 148 | + |
| 149 | + // Rule names prefixed with jest/ |
| 150 | + 'plugin:jest/recommended', |
| 151 | + ], |
| 152 | + overrides: [ |
| 153 | + { |
| 154 | + files: ['*_spec.js'], // cypress specs |
| 155 | + rules: { |
| 156 | + 'jest/expect-expect': 'off', |
| 157 | + }, |
| 158 | + }, |
| 159 | + ], |
| 160 | + parser: '@babel/eslint-parser', |
| 161 | + parserOptions: { |
| 162 | + ecmaFeatures: { |
| 163 | + jsx: true, |
| 164 | + }, |
| 165 | + sourceType: 'module', |
| 166 | + }, |
| 167 | + plugins: ['jest'], |
| 168 | + rules: { |
| 169 | + ...airbnbOverrides, |
| 170 | + ...temporaryOverrides, |
| 171 | + }, |
| 172 | + settings: { |
| 173 | + 'import/resolver': { |
| 174 | + node: { |
| 175 | + paths: ['src'], |
| 176 | + }, |
| 177 | + }, |
| 178 | + }, |
| 179 | +} |
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