javascript.md

javascript config

Default config, suitable for any JavaScript/TypeScript project.

🏗️ Setup

Refer to setup instructions in README.

📏 Rules (290)

🔧 Automatically fixable by the --fix CLI option.
💡 Manually fixable by editor suggestions.
🧪🚫 Disabled for test files.
🧪⚠️ Severity lessened to warning for test files.

🚨 Errors (120)

Plugin	Rule	Options	Autofix	Overrides
	constructor-super Require super() calls in constructors
	eqeqeq Require the use of === and !==	always, null: never [ "always", { "null": "never" } ]	🔧
	for-direction Enforce "for" loop update clause moving the counter in the right direction
	getter-return Enforce return statements in getters
	guard-for-in Require for-in loops to include an if statement
	no-async-promise-executor Disallow using an async function as a Promise executor
	no-case-declarations Disallow lexical declarations in case clauses		💡
	no-class-assign Disallow reassigning class members
	no-compare-neg-zero Disallow comparing against -0
	no-cond-assign Disallow assignment operators in conditional expressions
	no-const-assign Disallow reassigning const variables
	no-constant-binary-expression Disallow expressions where the operation doesn't affect the value
	no-constant-condition Disallow constant expressions in conditions
	no-control-regex Disallow control characters in regular expressions
	no-debugger Disallow the use of debugger
	no-delete-var Disallow deleting variables
	no-dupe-args Disallow duplicate arguments in function definitions
	no-dupe-class-members Disallow duplicate class members
	no-dupe-else-if Disallow duplicate conditions in if-else-if chains
	no-dupe-keys Disallow duplicate keys in object literals
	no-duplicate-case Disallow duplicate case labels
	no-empty Disallow empty block statements		💡
	no-empty-character-class Disallow empty character classes in regular expressions
	no-empty-pattern Disallow empty destructuring patterns
	no-eval Disallow the use of eval()
	no-ex-assign Disallow reassigning exceptions in catch clauses
	no-extra-boolean-cast Disallow unnecessary boolean casts		🔧
	no-fallthrough Disallow fallthrough of case statements
	no-func-assign Disallow reassigning function declarations
	no-global-assign Disallow assignments to native objects or read-only global variables
	no-import-assign Disallow assigning to imported bindings
	no-inner-declarations Disallow variable or function declarations in nested blocks
	no-invalid-regexp Disallow invalid regular expression strings in RegExp constructors
	no-irregular-whitespace Disallow irregular whitespace
	no-loss-of-precision Disallow literal numbers that lose precision
	no-misleading-character-class Disallow characters which are made with multiple code points in character class syntax		💡
	no-new-native-nonconstructor Disallow new operators with global non-constructor functions
	no-nonoctal-decimal-escape Disallow \8 and \9 escape sequences in string literals		💡
	no-obj-calls Disallow calling global object properties as functions
	no-octal Disallow octal literals
	no-param-reassign Disallow reassigning function parameters	props: true { "props": true }
	no-prototype-builtins Disallow calling some Object.prototype methods directly on objects		💡
	no-redeclare Disallow variable redeclaration
	no-regex-spaces Disallow multiple spaces in regular expressions		🔧
	no-self-assign Disallow assignments where both sides are exactly the same
	no-sequences Disallow comma operators
	no-setter-return Disallow returning values from setters
	no-shadow-restricted-names Disallow identifiers from shadowing restricted names
	no-sparse-arrays Disallow sparse arrays
	no-template-curly-in-string Disallow template literal placeholder syntax in regular strings
	no-this-before-super Disallow this/super before calling super() in constructors
	no-undef Disallow the use of undeclared variables unless mentioned in /*global */ comments
	no-unexpected-multiline Disallow confusing multiline expressions
	no-unreachable Disallow unreachable code after return, throw, continue, and break statements
	no-unreachable-loop Disallow loops with a body that allows only one iteration
	no-unsafe-finally Disallow control flow statements in finally blocks
	no-unsafe-negation Disallow negating the left operand of relational operators		💡
	no-unsafe-optional-chaining Disallow use of optional chaining in contexts where the undefined value is not allowed
	no-unused-labels Disallow unused labels		🔧
	no-unused-vars Disallow unused variables
	no-useless-backreference Disallow useless backreferences in regular expressions
	no-useless-catch Disallow unnecessary catch clauses
	no-useless-escape Disallow unnecessary escape characters		💡
	no-var Require let or const instead of var		🔧
	no-with Disallow with statements
	prefer-const Require const declarations for variables that are never reassigned after declared		🔧
	prefer-rest-params Require rest parameters instead of arguments
	prefer-spread Require spread operators instead of .apply()
	require-yield Require generator functions to contain yield
	use-isnan Require calls to isNaN() when checking for NaN		💡
	valid-typeof Enforce comparing typeof expressions against valid strings		💡
	ban-ts-comment Disallow @ts-<directive> comments or require descriptions after directives		💡
	no-array-constructor Disallow generic Array constructors		🔧
	no-duplicate-enum-values Disallow duplicate enum member values
	no-empty-object-type Disallow accidentally using the "empty object" type		💡
	no-explicit-any Disallow the any type		🔧, 💡	🧪🚫
	no-extra-non-null-assertion Disallow extra non-null assertions		🔧
	no-misused-new Enforce valid definition of new and constructor
	no-namespace Disallow TypeScript namespaces
	no-non-null-asserted-optional-chain Disallow non-null assertions after an optional chain expression		💡
	no-require-imports Disallow invocation of require()
	no-this-alias Disallow aliasing this
	no-unnecessary-type-constraint Disallow unnecessary constraints on generic types		💡
	no-unsafe-declaration-merging Disallow unsafe declaration merging
	no-unsafe-function-type Disallow using the unsafe built-in Function type		🔧
	no-unused-vars Disallow unused variables	argsIgnorePattern: ^, dest... { "argsIgnorePattern": "^", "destructuredArrayIgnorePattern": "^_", "ignoreRestSiblings": true }
	no-wrapper-object-types Disallow using confusing built-in primitive class wrappers		🔧
	prefer-as-const Enforce the use of as const over literal type		🔧, 💡
	triple-slash-reference Disallow certain triple slash directives in favor of ES6-style import declarations
	default Ensure a default export is present, given a default import.
	export Forbid any invalid exports, i.e. re-export of the same name.
	named Ensure named imports correspond to a named export in the remote file.
	namespace Ensure imported namespaces contain dereferenced properties as they are dereferenced.
	no-absolute-path Forbid import of modules using absolute paths.		🔧
	no-amd Forbid AMD require and define calls.
	no-commonjs Forbid CommonJS require calls and module.exports or exports.*.
	no-cycle Forbid a module from importing a module with a dependency path back to itself.
	no-mutable-exports Forbid the use of mutable exports with var or let.
	no-self-import Forbid a module from importing itself.
	no-unresolved Ensure imports point to a file/module that can be resolved.
	always-return Require returning inside each then() to create readable and reusable Promise chains.	ignoreLastCallback: true { "ignoreLastCallback": true }
	catch-or-return Enforce the use of catch() on un-returned promises.			🧪🚫
	no-new-statics Disallow calling new on a Promise static method.		🔧
	no-return-wrap Disallow wrapping values in Promise.resolve or Promise.reject when not needed.
	param-names Enforce consistent param names and ordering when creating new promises.
	no-all-duplicated-branches All branches in a conditional structure should not have exactly the same implementation
	no-collection-size-mischeck Collection sizes and array length comparisons should make sense		💡
	no-duplicated-branches Two branches in a conditional structure should not have exactly the same implementation
	no-element-overwrite Collection elements should not be replaced unconditionally
	no-empty-collection Empty collections should not be accessed or iterated
	no-extra-arguments Function calls should not pass extra arguments
	no-gratuitous-expressions Boolean expressions should not be gratuitous
	no-identical-conditions Related "if-else-if" and "switch-case" statements should not have the same condition
	no-identical-expressions Identical expressions should not be used on both sides of a binary operator
	no-identical-functions Functions should not have identical implementations
	no-ignored-return Return values from functions without side effects should not be ignored
	no-one-iteration-loop Loops with at most one iteration should be refactored
	no-unused-collection Collection and array contents should be used
	no-use-of-empty-return-value The output of functions that don't return anything should not be used
	non-existent-operator Non-existent operators "=+", "=-" and "=!" should not be used		💡

⚠️ Warnings (170)

Plugin	Rule	Options	Autofix	Overrides
	arrow-body-style Require braces around arrow function bodies	as-needed "as-needed"	🔧
	complexity Enforce a maximum cyclomatic complexity allowed in a program
	curly Enforce consistent brace style for all control statements		🔧	🧪🚫
	max-depth Enforce a maximum depth that blocks can be nested
	max-lines Enforce a maximum number of lines per file	skipBlankLines: true, skipC... { "skipBlankLines": true, "skipComments": true }		🧪🚫
	max-lines-per-function Enforce a maximum number of lines of code in a function	skipBlankLines: true, skipC... { "skipBlankLines": true, "skipComments": true }		🧪🚫
	max-nested-callbacks Enforce a maximum depth that callbacks can be nested	max: 10 { "max": 10 }
	no-bitwise Disallow bitwise operators
	no-console Disallow the use of console	allow: error, warn, info { "allow": [ "error", "warn", "info" ] }	💡
	no-duplicate-imports Disallow duplicate module imports
	no-empty-static-block Disallow empty static blocks
	no-undef-init Disallow initializing variables to undefined		🔧
	no-unused-private-class-members Disallow unused private class members
	no-useless-computed-key Disallow unnecessary computed property keys in objects and classes		🔧
	no-useless-rename Disallow renaming import, export, and destructured assignments to the same name		🔧
	object-shorthand Require or disallow method and property shorthand syntax for object literals		🔧
	prefer-template Require template literals instead of string concatenation		🔧
	radix Enforce the consistent use of the radix argument when using parseInt()		💡
	yoda Require or disallow "Yoda" conditions		🔧
	adjacent-overload-signatures Require that function overload signatures be consecutive
	array-type Require consistently using either T[] or Array<T> for arrays		🔧
	ban-tslint-comment Disallow // tslint:<rule-flag> comments		🔧
	class-methods-use-this Enforce that class methods utilize this
	consistent-generic-constructors Enforce specifying generic type arguments on type annotation or constructor name of a constructor call		🔧
	consistent-type-definitions Enforce type definitions to consistently use either interface or type	type "type"	🔧
	default-param-last Enforce default parameters to be last
	max-params Enforce a maximum number of parameters in function definitions	max: 4 { "max": 4 }
	method-signature-style Enforce using a particular method signature syntax		🔧
	no-confusing-non-null-assertion Disallow non-null assertion in locations that may be confusing		💡
	no-empty-function Disallow empty functions	allow: private-constructors... { "allow": [ "private-constructors", "protected-constructors", "decoratedFunctions", "overrideMethods" ] }		🧪🚫
	no-import-type-side-effects Enforce the use of top-level import type qualifier when an import only has specifiers with inline type qualifiers		🔧
	no-magic-numbers Disallow magic numbers	ignore: -1, 0, 1, 2, 7, 10,... { "ignore": [ -1, 0, 1, 2, 7, 10, 24, 60, 100, 1000, 3600 ], "ignoreClassFieldInitialValues": true, "ignoreDefaultValues": true, "ignoreEnums": true, "ignoreNumericLiteralTypes": true, "ignoreReadonlyClassProperties": true, "ignoreTypeIndexes": true, "enforceConst": true, "detectObjects": true }		🧪🚫
	no-shadow Disallow variable declarations from shadowing variables declared in the outer scope
	no-unused-expressions Disallow unused expressions
	prefer-function-type Enforce using function types instead of interfaces with call signatures		🔧
	prefer-namespace-keyword Require using namespace keyword over module keyword to declare custom TypeScript modules		🔧
	no-let Disallow mutable variables.			🧪🚫
	no-loop-statements Disallow imperative loops.
	max-dependencies Enforce the maximum number of dependencies a module can have.	ignoreTypeImports: true { "ignoreTypeImports": true }
	no-anonymous-default-export Forbid anonymous values as default exports.
	no-duplicates Forbid repeated import of the same module in multiple places.		🔧
	no-named-as-default Forbid use of exported name as identifier of default export.
	no-named-as-default-member Forbid use of exported name as property of default export.
	no-named-default Forbid named default exports.
	no-unassigned-import Forbid unassigned imports
	no-useless-path-segments Forbid unnecessary path segments in import and require statements.		🔧
	no-callback-in-promise Disallow calling cb() inside of a then() (use [nodeify][] instead).	exceptions: next { "exceptions": [ "next" ] }
	no-nesting Disallow nested then() or catch() statements.
	no-promise-in-callback Disallow using promises inside of callbacks.
	no-return-in-finally Disallow return statements in finally().
	valid-params Enforces the proper number of arguments are passed to Promise functions.
	max-switch-cases "switch" statements should not have too many "case" clauses
	no-collapsible-if Collapsible "if" statements should be merged
	no-duplicate-string String literals should not be duplicated			🧪🚫
	no-inverted-boolean-check Boolean checks should not be inverted		🔧, 💡
	no-nested-switch "switch" statements should not be nested
	no-nested-template-literals Template literals should not be nested
	no-redundant-boolean Boolean literals should not be redundant
	no-redundant-jump Jump statements should not be redundant		💡
	no-same-line-conditional Conditionals should start on new lines		💡
	no-small-switch "switch" statements should have at least 3 "case" clauses
	no-useless-catch "catch" clauses should do more than rethrow
	prefer-immediate-return Local variables should not be declared and then immediately returned or thrown		🔧
	prefer-object-literal Object literal syntax should be used
	prefer-single-boolean-return Return of boolean expressions should not be wrapped into an "if-then-else" statement		💡
	prefer-while A "while" loop should be used instead of a "for" loop		🔧
	better-regex Improve regexes by making them shorter, consistent, and safer.	sortCharacterClasses: false { "sortCharacterClasses": false }	🔧
	catch-error-name Enforce a specific parameter name in catch clauses.		🔧
	consistent-destructuring Use destructured variables over properties.		🔧, 💡
	consistent-function-scoping Move function definitions to the highest possible scope.	checkArrowFunctions: false { "checkArrowFunctions": false }		🧪🚫
	empty-brace-spaces Enforce no spaces between braces.		🔧
	error-message Enforce passing a message value when creating a built-in error.
	escape-case Require escape sequences to use uppercase values.		🔧
	expiring-todo-comments Add expiration conditions to TODO comments.
	explicit-length-check Enforce explicitly comparing the length or size property of a value.		🔧, 💡
	filename-case Enforce a case style for filenames.
	import-style Enforce specific import styles per module.
	new-for-builtins Enforce the use of new for all builtins, except String, Number, Boolean, Symbol and BigInt.		🔧
	no-abusive-eslint-disable Enforce specifying rules to disable in eslint-disable comments.
	no-array-callback-reference Prevent passing a function reference directly to iterator methods.		💡
	no-array-for-each Prefer for…of over the forEach method.		🔧, 💡
	no-array-method-this-argument Disallow using the this argument in array methods.		🔧, 💡
	no-array-push-push Enforce combining multiple Array#push() into one call.		🔧, 💡
	no-array-reduce Disallow Array#reduce() and Array#reduceRight().
	no-await-expression-member Disallow member access from await expression.		🔧
	no-console-spaces Do not use leading/trailing space between console.log parameters.		🔧
	no-document-cookie Do not use document.cookie directly.
	no-empty-file Disallow empty files.
	no-for-loop Do not use a for loop that can be replaced with a for-of loop.		🔧, 💡
	no-hex-escape Enforce the use of Unicode escapes instead of hexadecimal escapes.		🔧
	no-instanceof-array Require Array.isArray() instead of instanceof Array.		🔧
	no-invalid-remove-event-listener Prevent calling EventTarget#removeEventListener() with the result of an expression.
	no-lonely-if Disallow if statements as the only statement in if blocks without else.		🔧
	no-negated-condition Disallow negated conditions.		🔧
	no-nested-ternary Disallow nested ternary expressions.		🔧
	no-new-array Disallow new Array().		🔧, 💡
	no-new-buffer Enforce the use of Buffer.from() and Buffer.alloc() instead of the deprecated new Buffer().		🔧, 💡
	no-null Disallow the use of the null literal.		🔧, 💡
	no-object-as-default-parameter Disallow the use of objects as default parameters.
	no-process-exit Disallow process.exit().
	no-static-only-class Disallow classes that only have static members.		🔧
	no-thenable Disallow then property.
	no-this-assignment Disallow assigning this to a variable.
	no-typeof-undefined Disallow comparing undefined using typeof.		🔧, 💡
	no-unnecessary-await Disallow awaiting non-promise values.		🔧
	no-unnecessary-polyfills Enforce the use of built-in methods instead of unnecessary polyfills.
	no-unreadable-array-destructuring Disallow unreadable array destructuring.		🔧
	no-unreadable-iife Disallow unreadable IIFEs.
	no-useless-fallback-in-spread Disallow useless fallback when spreading in object literals.		🔧
	no-useless-length-check Disallow useless array length check.		🔧
	no-useless-promise-resolve-reject Disallow returning/yielding Promise.resolve/reject() in async functions or promise callbacks		🔧
	no-useless-spread Disallow unnecessary spread.		🔧
	no-useless-switch-case Disallow useless case in switch statements.		💡
	no-useless-undefined Disallow useless undefined.	checkArguments: false { "checkArguments": false }	🔧
	no-zero-fractions Disallow number literals with zero fractions or dangling dots.		🔧
	number-literal-case Enforce proper case for numeric literals.		🔧
	numeric-separators-style Enforce the style of numeric separators by correctly grouping digits.		🔧
	prefer-add-event-listener Prefer .addEventListener() and .removeEventListener() over on-functions.		🔧
	prefer-array-find Prefer .find(…) and .findLast(…) over the first or last element from .filter(…).		🔧, 💡
	prefer-array-flat Prefer Array#flat() over legacy techniques to flatten arrays.		🔧
	prefer-array-flat-map Prefer .flatMap(…) over .map(…).flat().		🔧
	prefer-array-index-of Prefer Array#{indexOf,lastIndexOf}() over Array#{findIndex,findLastIndex}() when looking for the index of an item.		🔧, 💡
	prefer-array-some Prefer .some(…) over .filter(…).length check and .{find,findLast}(…).		🔧, 💡
	prefer-at Prefer .at() method for index access and String#charAt().		🔧, 💡
	prefer-blob-reading-methods Prefer Blob#arrayBuffer() over FileReader#readAsArrayBuffer(…) and Blob#text() over FileReader#readAsText(…).
	prefer-code-point Prefer String#codePointAt(…) over String#charCodeAt(…) and String.fromCodePoint(…) over String.fromCharCode(…).		💡
	prefer-date-now Prefer Date.now() to get the number of milliseconds since the Unix Epoch.		🔧
	prefer-default-parameters Prefer default parameters over reassignment.		🔧, 💡
	prefer-dom-node-append Prefer Node#append() over Node#appendChild().		🔧
	prefer-dom-node-dataset Prefer using .dataset on DOM elements over calling attribute methods.		🔧
	prefer-dom-node-remove Prefer childNode.remove() over parentNode.removeChild(childNode).		🔧, 💡
	prefer-dom-node-text-content Prefer .textContent over .innerText.		💡
	prefer-event-target Prefer EventTarget over EventEmitter.
	prefer-export-from Prefer export…from when re-exporting.		🔧, 💡
	prefer-includes Prefer .includes() over .indexOf() and Array#some() when checking for existence or non-existence.		🔧, 💡
	prefer-keyboard-event-key Prefer KeyboardEvent#key over KeyboardEvent#keyCode.		🔧
	prefer-logical-operator-over-ternary Prefer using a logical operator over a ternary.		💡
	prefer-math-trunc Enforce the use of Math.trunc instead of bitwise operators.		🔧, 💡
	prefer-modern-dom-apis Prefer .before() over .insertBefore(), .replaceWith() over .replaceChild(), prefer one of .before(), .after(), .append() or .prepend() over insertAdjacentText() and insertAdjacentElement().		🔧
	prefer-modern-math-apis Prefer modern Math APIs over legacy patterns.		🔧
	prefer-module Prefer JavaScript modules (ESM) over CommonJS.		🔧, 💡
	prefer-native-coercion-functions Prefer using String, Number, BigInt, Boolean, and Symbol directly.		🔧
	prefer-negative-index Prefer negative index over .length - index when possible.		🔧
	prefer-node-protocol Prefer using the node: protocol when importing Node.js builtin modules.		🔧
	prefer-number-properties Prefer Number static properties over global ones.		🔧, 💡
	prefer-object-from-entries Prefer using Object.fromEntries(…) to transform a list of key-value pairs into an object.		🔧
	prefer-optional-catch-binding Prefer omitting the catch binding parameter.		🔧
	prefer-prototype-methods Prefer borrowing methods from the prototype instead of the instance.		🔧
	prefer-query-selector Prefer .querySelector() over .getElementById(), .querySelectorAll() over .getElementsByClassName() and .getElementsByTagName().		🔧
	prefer-reflect-apply Prefer Reflect.apply() over Function#apply().		🔧
	prefer-regexp-test Prefer RegExp#test() over String#match() and RegExp#exec().		🔧, 💡
	prefer-set-has Prefer Set#has() over Array#includes() when checking for existence or non-existence.		🔧, 💡
	prefer-set-size Prefer using Set#size instead of Array#length.		🔧
	prefer-spread Prefer the spread operator over Array.from(…), Array#concat(…), Array#{slice,toSpliced}() and String#split('').		🔧, 💡
	prefer-string-replace-all Prefer String#replaceAll() over regex searches with the global flag.		🔧
	prefer-string-slice Prefer String#slice() over String#substr() and String#substring().		🔧
	prefer-string-starts-ends-with Prefer String#startsWith() & String#endsWith() over RegExp#test().		🔧, 💡
	prefer-string-trim-start-end Prefer String#trimStart() / String#trimEnd() over String#trimLeft() / String#trimRight().		🔧
	prefer-switch Prefer switch over multiple else-if.		🔧
	prefer-ternary Prefer ternary expressions over simple if-else statements.		🔧
	prefer-top-level-await Prefer top-level await over top-level promises and async function calls.		💡
	prefer-type-error Enforce throwing TypeError in type checking conditions.		🔧
	prevent-abbreviations Prevent abbreviations.		🔧
	relative-url-style Enforce consistent relative URL style.		🔧, 💡
	require-array-join-separator Enforce using the separator argument with Array#join().		🔧
	require-number-to-fixed-digits-argument Enforce using the digits argument with Number#toFixed().		🔧
	switch-case-braces Enforce consistent brace style for case clauses.	avoid "avoid"	🔧
	template-indent Fix whitespace-insensitive template indentation.		🔧
	text-encoding-identifier-case Enforce consistent case for text encoding identifiers.		🔧, 💡
	throw-new-error Require new when throwing an error.		🔧