@jsenv/eslint-config
Version:
Create ESLint configuration for any project
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JavaScript
;
Object.defineProperty(exports, Symbol.toStringTag, { value: 'Module' });
const composeTwoObjects = (first, second, composerMap) => {
const composed = {};
const firstKeys = Object.keys(first);
const secondKeys = Object.keys(second);
Object.keys(first).forEach((key) => {
composed[key] = secondKeys.includes(key)
? composeTwoValues(first[key], second[key], composerMap[key])
: first[key];
});
Object.keys(second).forEach((key) => {
if (!firstKeys.includes(key)) {
composed[key] = second[key];
}
});
return composed;
};
const composeTwoValues = (firstValue, secondValue, composer) => {
if (composer) {
return composer(firstValue, secondValue);
}
return secondValue;
};
const composeEslintConfig = (...eslintConfigs) => {
return eslintConfigs.reduce((previous, current) => {
const next = composeTwoEslintConfigs(previous, current);
return next;
}, {});
};
const composeTwoEslintConfigs = (firstEslintConfig, secondEslintConfig) => {
return composeTwoObjects(firstEslintConfig, secondEslintConfig, {
parserOptions: (firstParserOptions, secondParserOptions) => {
return composeTwoObjects(firstParserOptions, secondParserOptions, {
ecmaFeatures: (firstEcmaFeatures, secondEcmaFeatures) => {
return {
...firstEcmaFeatures,
...secondEcmaFeatures,
};
},
});
},
env: (firstEnv, secondEnv) => {
return {
...firstEnv,
...secondEnv,
};
},
globals: (firstGlobals, secondGlobals) => {
return {
...firstGlobals,
...secondGlobals,
};
},
plugins: (firstPlugins, secondPlugins) => {
return [...firstPlugins, ...secondPlugins];
},
settings: (firstSettings, secondSettings) => {
return composeTwoObjects(firstSettings, secondSettings, {
extensions: (firstExtensions, secondExtensions) => {
return [...firstExtensions, ...secondExtensions];
},
});
},
rules: (firstRules, secondRules) => {
return {
...firstRules,
...secondRules,
};
},
overrides: (firstOverrides, secondOverrides) => {
return [...firstOverrides, ...secondOverrides];
},
});
};
/**
* This super basic ESLint configuration to parse latest js
*/
const eslintConfigBase = {
parserOptions: {
sourceType: "module",
},
env: {
es2022: true,
},
settings: {
extensions: [".js", ".mjs"],
},
};
/**
* This ESLint config object is setting a list of rules to "off" as they will be already handled by prettier.
* To ensure rules remains configured to "off", keep eslintConfigForPrettier low, ideally last during eslint composition
*
* See also https://github.com/prettier/eslint-config-prettier/blob/master/index.js
*/
const eslintConfigForPrettier = {
rules: {
"arrow-parens": ["off"],
"arrow-spacing": ["off"],
"brace-style": ["off"],
"comma-dangle": ["off"],
"comma-style": ["off"],
"computed-property-spacing": ["off"],
"curly": ["off"],
"dot-location": ["off"],
"eol-last": ["off"],
"generator-star-spacing": ["off"],
"indent": ["off"],
"jsx-quotes": ["off"],
"key-spacing": ["off"],
"keyword-spacing": ["off"],
"max-len": ["off"],
"no-confusing-arrow": ["off"], // prettier makes it non confusing
"no-extra-semi": ["off"],
"no-floating-decimal": ["off"],
"no-mixed-spaces-and-tabs": ["off"],
"no-multi-spaces": ["off"],
"no-multi-str": ["off"],
"no-multiple-empty-lines": ["off"],
"no-trailing-spaces": ["off"],
"no-unexpected-multiline": ["off"],
"no-whitespace-before-property": ["off"],
"object-curly-spacing": ["off"],
"one-var-declaration-per-line": ["off"],
"operator-linebreak": ["off"],
"padded-blocks": ["off"],
"quote": ["off"],
"quote-props": ["off"],
"semi": ["off"],
"semi-spacing": ["off"],
"space-before-blocks": ["off"],
"space-before-function-paren": ["off"],
"space-in-parens": ["off"],
"space-infix-ops": ["off"],
"template-curly-spacing": ["off"],
"wrap-iife": ["off"],
"yield-star-spacing": ["off"],
},
};
/*
* ESLint rightfully consider some globals as available but in practice it prevents to catch bugs.
* It's better for human devs to configure ESLint so that "close" or "event" are undefined by default.
* If one day code needs to use the global variable you can still write window.close or window.event.
*
* See also
* - https://github.com/eslint/eslint/blob/00d2c5be9a89efd90135c4368a9589f33df3f7ba/conf/environments.js#L1
* - https://github.com/sindresorhus/globals/blob/a1d32c7f76e4d1ac3c8883acf075db11bd4d44f9/globals.json#L1
*
*/
const eslintConfigToPreferExplicitGlobals = {
globals: {
alert: "off",
atob: "off",
blur: "off",
btoa: "off",
caches: "off",
close: "off",
closed: "off",
crypto: "off",
defaultstatus: "off",
defaultStatus: "off",
escape: "off",
event: "off",
external: "off",
focus: "off",
find: "off",
frames: "off",
history: "off",
length: "off",
location: "off",
menubar: "off",
name: "off",
navigator: "off",
open: "off",
origin: "off",
print: "off",
screen: "off",
scroll: "off",
status: "off",
stop: "off",
top: "off",
unescape: "off",
valueOf: "off",
},
};
/*
* Contains configuration of many ESLint rules with the following mindset:
* 1. ESLint should fail only for important things
* 2. ESLint should be silent as long as nothing critical is detected
* 3. When code is slighly modified to test/debug something, please ESLint, let me do without
* bothering me with "best practices" and stuff
*
* Notes:
* - Point 3. is the reason why rules like "prefer-const" are disabled
* - It's on purpose that point "2." is an other way of phrasing "1."
* - There is a few exception to mindset, for example "no-eval" is not really
* critical but the rule is still enabled
*
* See also:
* - https://eslint.org/docs/rules/
*/
const jsenvEslintRules = {
"accessor-pairs": ["error"],
"array-bracket-spacing": ["error", "never"],
"array-callback-return": ["error"],
"arrow-parens": ["error", "as-needed"],
"arrow-spacing": ["error", { before: true, after: true }],
"block-scoped-var": ["error"],
"brace-style": ["error", "stroustrup"],
"camelcase": [
"off",
{
properties: "always",
},
],
"comma-dangle": [
"error",
{
arrays: "only-multiline",
objects: "only-multiline",
imports: "only-multiline",
exports: "only-multiline",
functions: "only-multiline",
},
],
"comma-spacing": [
"error",
{
before: false,
after: true,
},
],
"comma-style": ["error", "last"],
"computed-property-spacing": ["error", "never"],
"consistent-return": ["error"],
"constructor-super": ["error"],
"curly": ["error"],
"default-case": ["error"],
"dot-location": ["error", "property"],
"dot-notation": ["error"],
"eol-last": ["off"],
"eqeqeq": ["error"],
"generator-star-spacing": ["error", "both"],
"getter-return": ["error"],
"grouped-accessor-pairs": ["error"],
"guard-for-in": ["error"],
"handle-callback-err": ["warn"],
/**
* "tab" is theorically a better option so that people can choose identation width.
* Because it allow them to decide how much space a tab char takes (2, 4, 100) in their environment
* But it comes with several issue:
* - By default github will render a tab with 8 spaces
* (can be fixed thank to an .editorconfig at the root of the github project (see http://stackoverflow.com/a/33831598)
* - A user cannot globally defined how much space a tab should take
* In a perfect world it would be an operating system setting that browser
* would follow.
*
* In practice spaces cause less troubles.
*/
"indent": ["error", 2, { SwitchCase: 1 }],
"jsx-quotes": ["error"],
"key-spacing": [
"error",
{
beforeColon: false,
afterColon: true,
},
],
"keyword-spacing": ["error"],
// disabled otherwise fails when eslint is runned on windows
// after a git clone
"linebreak-style": ["off", "unix"],
"max-len": [
"warn",
120,
4,
{
ignoreComments: true,
ignoreUrls: true,
ignorePattern: "^\\s*var\\s.+=\\s.+\\/.*?\\/;$",
},
],
"max-nested-callbacks": ["warn", 4],
"new-cap": [
"error",
{
newIsCap: true,
capIsNew: false,
},
],
"new-parens": ["error"],
"no-alert": ["error"],
"no-array-constructor": ["error"],
"no-caller": ["error"],
"no-case-declarations": ["error"],
"no-class-assign": ["error"],
"no-cond-assign": ["error"],
"no-confusing-arrow": ["error"],
"no-const-assign": ["error"],
"no-constant-condition": ["error"],
"no-constant-binary-expression": ["error"],
"no-constructor-return": ["error"],
"no-control-regex": ["error"],
"no-debugger": process.env.CI ? ["error"] : ["off"],
"no-delete-var": ["error"],
"no-div-regex": ["error"],
"no-dupe-args": ["error"],
"no-duplicate-case": ["error"],
"no-dupe-class-members": ["error"],
"no-dupe-else-if": ["error"],
"no-dupe-keys": ["error"],
"no-else-return": ["error"],
"no-empty-character-class": ["error"],
"no-empty-pattern": ["error"],
"no-eq-null": ["error"],
"no-extend-native": ["error"],
"no-ex-assign": ["error"],
"no-extra-bind": ["error"],
"no-extra-boolean-cast": ["error"],
"no-extra-label": ["error"],
"no-extra-semi": ["off"],
// At first I wanted to disable "no-eval" because every one knows eval is a bad idea
// so when it's used it's always for a good reason.
// But on second thought it's better to disable the rule
// locally using "//eslint-disable-next-line no-eval" in that case
"no-eval": ["error"],
"no-fallthrough": ["error"],
"no-floating-decimal": ["error"],
"no-func-assign": ["error"],
"no-inner-declarations": ["error"],
"no-invalid-regexp": ["error"],
"no-implicit-coercion": ["error"],
"no-implicit-globals": ["error"],
"no-implied-eval": ["error"],
"no-irregular-whitespace": ["error"],
"no-iterator": ["error"],
"no-label-var": ["error"],
"no-labels": ["off"], // https://gist.github.com/getify/706e5e10822a298375da40f9cc1fa295
"no-lone-blocks": ["off"], // https://gist.github.com/getify/706e5e10822a298375da40f9cc1fa295
"no-lonely-if": ["error"],
"no-loop-func": ["error"],
"no-magic-numbers": ["off"],
"no-mixed-requires": ["error", { grouping: true, allowCall: true }],
"no-mixed-spaces-and-tabs": ["error"],
"no-multi-spaces": ["error"],
"no-multi-str": ["error"],
"no-multiple-empty-lines": ["off", { max: 1 }],
"no-native-reassign": ["error"],
"no-negated-condition": ["error"],
// disabled because deprecated in favor of no-unsafe-negation
// https://eslint.org/docs/rules/no-negated-in-lhs
"no-negated-in-lhs": ["off"],
// I prefer when ESLint really has something to say
// nested ternary are not wrong, especially when prettier
// format them correctly
// In the end, they often gets transformed to helper function
// but in the meantime eslint is complaining
"no-nested-ternary": ["off"],
"no-new": ["error"],
"no-new-func": ["error"],
"no-new-require": ["error"],
"no-new-object": ["error"],
"no-new-symbol": ["error"],
"no-new-wrappers": ["error"],
"no-obj-calls": ["error"],
"no-octal": ["error"],
"no-octal-escape": ["error"],
"no-path-concat": ["error"],
"no-proto": ["error"],
"no-redeclare": ["error"],
"no-regex-spaces": ["error"],
"no-restricted-imports": [
"error",
"domain",
"freelist",
"smalloc",
"sys",
"colors",
],
"no-restricted-modules": [
"error",
"domain",
"freelist",
"smalloc",
"sys",
"colors",
],
"no-restricted-syntax": ["error", "WithStatement"],
"no-return-assign": ["error", "always"],
"no-setter-return": ["error"],
"no-script-url": ["error"],
"no-self-assign": ["error"],
"no-self-compare": ["error"],
"no-sequences": ["error"],
"no-shadow-restricted-names": ["error"],
"no-spaced-func": ["error"],
"no-sparse-arrays": ["error"],
"no-this-before-super": ["error"],
"no-throw-literal": ["error"],
"no-trailing-spaces": ["error"],
"no-undef": ["error", { typeof: true }],
"no-undef-init": ["error"],
"no-undefined": ["off"],
"no-unexpected-multiline": ["error"],
"no-unmodified-loop-condition": ["error"],
"no-unneeded-ternary": ["error"],
"no-unreachable": ["error"],
"no-unused-expressions": ["error"],
"no-unused-labels": ["off"], // https://gist.github.com/getify/706e5e10822a298375da40f9cc1fa295
"no-unused-private-class-members": ["error"],
"no-unused-vars": ["error"],
"no-use-before-define": [
"error",
/*
* "no-use-before-define" is great to prevent a common mistake
* where code tries to use a variable before it's actually available.
* In practice this rule fails even on valid code.
* Enabling the default options of this rule would
* force variables,functions and classes to be declared in specific order
* which is very annoying because:
* - code is valid in the first place
* - it's SUPER NICE to put variables and functions that are
* implementation details at the bottom of the file to make
* important code more accesible
*/
{
functions: false,
variables: false,
classes: false,
allowNamedExports: true,
},
],
"no-useless-call": ["error"],
"no-useless-concat": ["error"],
"no-useless-constructor": ["error"],
"no-void": ["error"],
"no-warning-comments": ["off"],
"no-whitespace-before-property": ["error"],
"no-with": ["error"],
"object-curly-spacing": ["error", "always"],
"object-shorthand": ["warn", "always"],
"one-var": ["error", "never"],
"one-var-declaration-per-line": ["error"],
// Sometimes I prefer to write toto = toto + 1
// instead of toto++ for whatever reason
// and having ESLint to complain is annoying
// I prefer when ESLint really has something to say
"operator-assignment": ["off", "always"],
"operator-linebreak": [
"error",
"after",
{
overrides: { "?": "ignore", ":": "ignore" },
},
],
"padded-blocks": ["error", "never"],
// I prefer to use const to indicate immediatly to the reader
// that this variable is never re-assigned. let becomes
// the exception and it helps to understand the code.
// However during development a variable gets used once
// and should be const, then you reuse it, and should be let.
// I prefer ESLint to stay quiet during these moments.
// I already got the habit of using const and would not care
// if some let where to stay by mistake.
"prefer-const": [
"off",
{
destructuring: "all",
ignoreReadBeforeAssign: true,
},
],
// Math.pow is cool, why being so strict ?
"prefer-exponentiation-operator": ["off"],
"prefer-rest-params": ["warn"],
"prefer-spread": ["warn"],
"prefer-template": ["warn"],
"quote": [
// disabled because it becomes painfull when switching
// between "" and `` (template literals)
"off",
// double because closer to .json, this it increase compatibility between .js and .json
// also because ' are often used in english and '' would lead to 'I\'m' VS "I'm"
"double",
],
"quote-props": [
"error",
"as-needed",
{
keywords: false,
numbers: true,
// unnecessary: false so that when you fall into edge cases
// you can use the quoting style you want
unnecessary: false,
},
],
"semi": ["error", "always"],
"semi-spacing": [
"error",
{
before: false,
after: true,
},
],
"space-before-blocks": ["error", "always"],
"space-before-function-paren": ["error", "never"],
"space-in-parens": ["error", "never"],
"space-infix-ops": ["error"],
"space-unary-ops": ["error"],
"spaced-comment": [
"error",
"always",
{
markers: ["!"],
},
],
"template-curly-spacing": ["error"],
"use-isnan": ["error"],
"valid-jsdoc": [
"off",
{
requireReturn: false,
prefer: {
returns: "return",
},
},
],
"valid-typeof": ["error"],
"wrap-iife": ["error", "inside"],
"yield-star-spacing": ["error", "both"],
"yoda": ["error"],
};
/*
* Contains configuration of ESLint rules when using eslint-plugin-import.
*
* Check ./jsenvEslintRules.js to see the mindset used to configure these rules
*/
const jsenvEslintRulesForImport = {
"import/default": ["error"],
"import/no-unresolved": [
"error",
{
commonjs: true,
amd: false,
caseSensitive: false,
},
],
"import/named": ["error"],
"import/namespace": ["error", { allowComputed: true }],
"import/no-absolute-path": ["off"],
"import/no-dynamic-require": ["error"],
"import/export": ["error"],
"import/no-named-as-default": ["warn"],
"import/first": ["warn"],
"import/no-duplicates": ["warn"],
"import/newline-after-import": ["warn"],
// "import/max-dependencies" is not super useful
// Either you will disable the eslint rule because it's "normal"
// to have a lot of dependencies or feel compelled to reduce the number of imports.
// It's already visible that a file has many imports and that ideally they should be
// less imports, no need for ESLint, let's keep ESLint for more valuable things.
"import/max-dependencies": ["off", { max: 10 }],
"import/no-anonymous-default-export": [
"off",
{
allowArray: true,
allowArrowFunction: false,
allowAnonymousClass: false,
allowAnonymousFunction: false,
allowLiteral: true,
allowObject: true,
},
],
"import/no-self-import": ["error"],
"import/no-cycle": ["error"],
"import/no-useless-path-segments": ["error"],
"import/no-default-export": ["error"],
};
/*
* Contains configuration of ESLint rules when using eslint-plugin-react.
*
* Check ./jsenvEslintRules.js to see the mindset used to configure these rules
*/
const jsenvEslintRulesForReact = {
"react/display-name": ["error"],
"react/jsx-key": ["error"],
"react/jsx-filename-extension": ["error", { extensions: [".jsx"] }],
"react/jsx-no-comment-textnodes": ["error"],
"react/jsx-no-duplicate-props": ["error"],
"react/jsx-no-target-blank": ["off"],
"react/jsx-no-undef": ["error"],
"react/jsx-uses-react": ["error"],
"react/jsx-uses-vars": ["error"],
"react/no-children-prop": ["error"],
"react/no-danger-with-children": ["error"],
"react/no-deprecated": ["error"],
"react/no-direct-mutation-state": ["error"],
"react/no-find-dom-node": ["error"],
"react/no-is-mounted": ["error"],
"react/no-render-return-value": ["error"],
"react/no-string-refs": ["error"],
"react/no-unescaped-entities": ["error"],
"react/no-unknown-property": ["error"],
"react/no-unsafe": ["off"],
"react/prop-types": ["off"],
"react/react-in-jsx-scope": ["error"],
"react/require-render-return": ["off"],
};
exports.composeEslintConfig = composeEslintConfig;
exports.eslintConfigBase = eslintConfigBase;
exports.eslintConfigForPrettier = eslintConfigForPrettier;
exports.eslintConfigToPreferExplicitGlobals = eslintConfigToPreferExplicitGlobals;
exports.jsenvEslintRules = jsenvEslintRules;
exports.jsenvEslintRulesForImport = jsenvEslintRulesForImport;
exports.jsenvEslintRulesForReact = jsenvEslintRulesForReact;
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