README.md

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@typescript-eslint/eslint-plugin includes over 100 rules that detect best practice violations, bugs, and/or stylistic issues specifically for TypeScript code. See Configs for how to enable recommended rules using configs.

Supported Rules

Key: ✅ = recommended, 🔒 = strict, 🔧 = fixable, 💭 = requires type information

Name	Description	✅🔒	🔧	💭
@typescript-eslint/adjacent-overload-signatures	Require that member overloads be consecutive	✅
@typescript-eslint/array-type	Requires using either T[] or Array<T> for arrays	🔒	🔧
@typescript-eslint/await-thenable	Disallows awaiting a value that is not a Thenable	✅		💭
@typescript-eslint/ban-ts-comment	Bans @ts-<directive> comments from being used or requires descriptions after directive	✅
@typescript-eslint/ban-tslint-comment	Bans // tslint:<rule-flag> comments from being used	🔒	🔧
@typescript-eslint/ban-types	Bans specific types from being used	✅	🔧
@typescript-eslint/class-literal-property-style	Ensures that literals on classes are exposed in a consistent style	🔒	🔧
@typescript-eslint/consistent-indexed-object-style	Enforce or disallow the use of the record type	🔒	🔧
@typescript-eslint/consistent-type-assertions	Enforces consistent usage of type assertions	🔒
@typescript-eslint/consistent-type-definitions	Consistent with type definition either interface or type	🔒	🔧
@typescript-eslint/consistent-type-exports	Enforces consistent usage of type exports		🔧	💭
@typescript-eslint/consistent-type-imports	Enforces consistent usage of type imports		🔧
@typescript-eslint/explicit-function-return-type	Require explicit return types on functions and class methods
@typescript-eslint/explicit-member-accessibility	Require explicit accessibility modifiers on class properties and methods		🔧
@typescript-eslint/explicit-module-boundary-types	Require explicit return and argument types on exported functions' and classes' public class methods
@typescript-eslint/member-delimiter-style	Require a specific member delimiter style for interfaces and type literals		🔧
@typescript-eslint/member-ordering	Require a consistent member declaration order
@typescript-eslint/method-signature-style	Enforces using a particular method signature syntax		🔧
@typescript-eslint/naming-convention	Enforces naming conventions for everything across a codebase			💭
@typescript-eslint/no-base-to-string	Requires that .toString() is only called on objects which provide useful information when stringified	🔒		💭
@typescript-eslint/no-confusing-non-null-assertion	Disallow non-null assertion in locations that may be confusing	🔒	🔧
@typescript-eslint/no-confusing-void-expression	Requires expressions of type void to appear in statement position		🔧	💭
@typescript-eslint/no-duplicate-enum-values	Disallow duplicate enum member values	🔒
@typescript-eslint/no-dynamic-delete	Disallow the delete operator with computed key expressions	🔒	🔧
@typescript-eslint/no-empty-interface	Disallow the declaration of empty interfaces	✅	🔧
@typescript-eslint/no-explicit-any	Disallow usage of the any type	✅	🔧
@typescript-eslint/no-extra-non-null-assertion	Disallow extra non-null assertion	✅	🔧
@typescript-eslint/no-extraneous-class	Forbids the use of classes as namespaces	🔒
@typescript-eslint/no-floating-promises	Requires Promise-like statements to be handled appropriately	✅		💭
@typescript-eslint/no-for-in-array	Disallow iterating over an array with a for-in loop	✅		💭
@typescript-eslint/no-inferrable-types	Disallows explicit type declarations for variables or parameters initialized to a number, string, or boolean	✅	🔧
@typescript-eslint/no-invalid-void-type	Disallows usage of void type outside of generic or return types	🔒
@typescript-eslint/no-meaningless-void-operator	Disallow the void operator except when used to discard a value	🔒	🔧	💭
@typescript-eslint/no-misused-new	Enforce valid definition of new and constructor	✅
@typescript-eslint/no-misused-promises	Avoid using Promises in places not designed to handle them	✅		💭
@typescript-eslint/no-namespace	Disallow the use of custom TypeScript modules and namespaces	✅
@typescript-eslint/no-non-null-asserted-nullish-coalescing	Disallows using a non-null assertion in the left operand of the nullish coalescing operator	🔒
@typescript-eslint/no-non-null-asserted-optional-chain	Disallows using a non-null assertion after an optional chain expression	✅
@typescript-eslint/no-non-null-assertion	Disallows non-null assertions using the ! postfix operator	✅
@typescript-eslint/no-parameter-properties	Disallow the use of parameter properties in class constructors
@typescript-eslint/no-redundant-type-constituents	Disallow members of unions and intersections that do nothing or override type information			💭
@typescript-eslint/no-require-imports	Disallows invocation of require()
@typescript-eslint/no-this-alias	Disallow aliasing this	✅
@typescript-eslint/no-type-alias	Disallow the use of type aliases
@typescript-eslint/no-unnecessary-boolean-literal-compare	Flags unnecessary equality comparisons against boolean literals	🔒	🔧	💭
@typescript-eslint/no-unnecessary-condition	Prevents conditionals where the type is always truthy or always falsy	🔒	🔧	💭
@typescript-eslint/no-unnecessary-qualifier	Warns when a namespace qualifier is unnecessary		🔧	💭
@typescript-eslint/no-unnecessary-type-arguments	Enforces that type arguments will not be used if not required	🔒	🔧	💭
@typescript-eslint/no-unnecessary-type-assertion	Warns if a type assertion does not change the type of an expression	✅	🔧	💭
@typescript-eslint/no-unnecessary-type-constraint	Disallows unnecessary constraints on generic types	✅
@typescript-eslint/no-unsafe-argument	Disallows calling a function with an any type value	✅		💭
@typescript-eslint/no-unsafe-assignment	Disallows assigning any to variables and properties	✅		💭
@typescript-eslint/no-unsafe-call	Disallows calling an any type value	✅		💭
@typescript-eslint/no-unsafe-member-access	Disallows member access on any typed variables	✅		💭
@typescript-eslint/no-unsafe-return	Disallows returning any from a function	✅		💭
@typescript-eslint/no-useless-empty-export	Disallow empty exports that don't change anything in a module file		🔧
@typescript-eslint/no-var-requires	Disallows the use of require statements except in import statements	✅
@typescript-eslint/non-nullable-type-assertion-style	Prefers a non-null assertion over explicit type cast when possible	🔒	🔧	💭
@typescript-eslint/parameter-properties	Require or disallow the use of parameter properties in class constructors
@typescript-eslint/prefer-as-const	Prefer usage of as const over literal type	✅	🔧
@typescript-eslint/prefer-enum-initializers	Prefer initializing each enums member value
@typescript-eslint/prefer-for-of	Prefer a ‘for-of’ loop over a standard ‘for’ loop if the index is only used to access the array being iterated	🔒
@typescript-eslint/prefer-function-type	Use function types instead of interfaces with call signatures	🔒	🔧
@typescript-eslint/prefer-includes	Enforce includes method over indexOf method	🔒	🔧	💭
@typescript-eslint/prefer-literal-enum-member	Require that all enum members be literal values to prevent unintended enum member name shadow issues	🔒
@typescript-eslint/prefer-namespace-keyword	Require the use of the namespace keyword instead of the module keyword to declare custom TypeScript modules	✅	🔧
@typescript-eslint/prefer-nullish-coalescing	Enforce the usage of the nullish coalescing operator instead of logical chaining	🔒		💭
@typescript-eslint/prefer-optional-chain	Prefer using concise optional chain expressions instead of chained logical ands	🔒
@typescript-eslint/prefer-readonly	Requires that private members are marked as readonly if they're never modified outside of the constructor		🔧	💭
@typescript-eslint/prefer-readonly-parameter-types	Requires that function parameters are typed as readonly to prevent accidental mutation of inputs			💭
@typescript-eslint/prefer-reduce-type-parameter	Prefer using type parameter when calling Array#reduce instead of casting	🔒	🔧	💭
@typescript-eslint/prefer-regexp-exec	Enforce that RegExp#exec is used instead of String#match if no global flag is provided		🔧	💭
@typescript-eslint/prefer-return-this-type	Enforce that this is used when only this type is returned	🔒	🔧	💭
@typescript-eslint/prefer-string-starts-ends-with	Enforce the use of String#startsWith and String#endsWith instead of other equivalent methods of checking substrings	🔒	🔧	💭
@typescript-eslint/prefer-ts-expect-error	Recommends using @ts-expect-error over @ts-ignore	🔒	🔧
@typescript-eslint/promise-function-async	Requires any function or method that returns a Promise to be marked async		🔧	💭
@typescript-eslint/require-array-sort-compare	Requires Array#sort calls to always provide a compareFunction			💭
@typescript-eslint/restrict-plus-operands	When adding two variables, operands must both be of type number or of type string	✅		💭
@typescript-eslint/restrict-template-expressions	Enforce template literal expressions to be of string type	✅		💭
@typescript-eslint/sort-type-union-intersection-members	Enforces that members of a type union/intersection are sorted alphabetically		🔧
@typescript-eslint/strict-boolean-expressions	Restricts the types allowed in boolean expressions		🔧	💭
@typescript-eslint/switch-exhaustiveness-check	Exhaustiveness checking in switch with union type			💭
@typescript-eslint/triple-slash-reference	Sets preference level for triple slash directives versus ES6-style import declarations	✅
@typescript-eslint/type-annotation-spacing	Require consistent spacing around type annotations		🔧
@typescript-eslint/typedef	Requires type annotations to exist
@typescript-eslint/unbound-method	Enforces unbound methods are called with their expected scope	✅		💭
@typescript-eslint/unified-signatures	Warns for any two overloads that could be unified into one by using a union or an optional/rest parameter	🔒

Extension Rules

In some cases, ESLint provides a rule itself, but it doesn't support TypeScript syntax; either it crashes, or it ignores the syntax, or it falsely reports against it. In these cases, we create what we call an extension rule; a rule within our plugin that has the same functionality, but also supports TypeScript.

Key: ✅ = recommended, 🔒 = strict, 🔧 = fixable, 💭 = requires type information

Name	Description	✅🔒	🔧	💭
@typescript-eslint/brace-style	Enforce consistent brace style for blocks		🔧
@typescript-eslint/comma-dangle	Require or disallow trailing comma		🔧
@typescript-eslint/comma-spacing	Enforces consistent spacing before and after commas		🔧
@typescript-eslint/default-param-last	Enforce default parameters to be last
@typescript-eslint/dot-notation	enforce dot notation whenever possible	🔒	🔧	💭
@typescript-eslint/func-call-spacing	Require or disallow spacing between function identifiers and their invocations		🔧
@typescript-eslint/indent	Enforce consistent indentation		🔧
@typescript-eslint/init-declarations	require or disallow initialization in variable declarations
@typescript-eslint/keyword-spacing	Enforce consistent spacing before and after keywords		🔧
@typescript-eslint/lines-between-class-members	Require or disallow an empty line between class members		🔧
@typescript-eslint/no-array-constructor	Disallow generic Array constructors	✅	🔧
@typescript-eslint/no-dupe-class-members	Disallow duplicate class members
@typescript-eslint/no-duplicate-imports	Disallow duplicate imports
@typescript-eslint/no-empty-function	Disallow empty functions	✅
@typescript-eslint/no-extra-parens	Disallow unnecessary parentheses		🔧
@typescript-eslint/no-extra-semi	Disallow unnecessary semicolons	✅	🔧
@typescript-eslint/no-implied-eval	Disallow the use of eval()-like methods	✅		💭
@typescript-eslint/no-invalid-this	Disallow this keywords outside of classes or class-like objects
@typescript-eslint/no-loop-func	Disallow function declarations that contain unsafe references inside loop statements
@typescript-eslint/no-loss-of-precision	Disallow literal numbers that lose precision	✅
@typescript-eslint/no-magic-numbers	Disallow magic numbers
@typescript-eslint/no-redeclare	Disallow variable redeclaration
@typescript-eslint/no-restricted-imports	Disallow specified modules when loaded by import
@typescript-eslint/no-shadow	Disallow variable declarations from shadowing variables declared in the outer scope
@typescript-eslint/no-throw-literal	Disallow throwing literals as exceptions	🔒		💭
@typescript-eslint/no-unused-expressions	Disallow unused expressions
@typescript-eslint/no-unused-vars	Disallow unused variables	✅
@typescript-eslint/no-use-before-define	Disallow the use of variables before they are defined
@typescript-eslint/no-useless-constructor	Disallow unnecessary constructors	🔒
@typescript-eslint/object-curly-spacing	Enforce consistent spacing inside braces		🔧
@typescript-eslint/padding-line-between-statements	require or disallow padding lines between statements		🔧
@typescript-eslint/quotes	Enforce the consistent use of either backticks, double, or single quotes		🔧
@typescript-eslint/require-await	Disallow async functions which have no await expression	✅		💭
@typescript-eslint/return-await	Enforces consistent returning of awaited values		🔧	💭
@typescript-eslint/semi	Require or disallow semicolons instead of ASI		🔧
@typescript-eslint/space-before-blocks	Enforces consistent spacing before blocks		🔧
@typescript-eslint/space-before-function-paren	Enforces consistent spacing before function parenthesis		🔧
@typescript-eslint/space-infix-ops	This rule is aimed at ensuring there are spaces around infix operators.		🔧