eslint/rules/types

Types: any, unsafe values, assertions, enums, interfaces, void and null: the type safety of TypeScript. Rules of ESLint, typescript-eslint and SonarJS (the Sonar way profile of SonarQube) on this subject, every rule listed; the TypeScript rules apply to TypeScript files only.

79 rules, 61 on. Source: lint/eslint/rules/types.mjs.

Rule	Setting	Files	What it checks	Why
no-prototype-builtins	error	JS + TS	Disallow calling some Object.prototype methods directly on objects	—
valid-typeof	error	JS + TS	Enforce comparing typeof expressions against valid strings	—
no-implicit-coercion	error	JS + TS	Disallow shorthand type conversions	—
no-new-wrappers	error	JS + TS	Disallow new operators with the String, Number, and Boolean objects	—
no-undefined	off	JS + TS	Disallow the use of undefined as an identifier	—
no-void	warn, {"allowAsStatement":true}	JS + TS	Disallow void operators	void promise; marks a promise as intentionally not awaited.
sonarjs/class-prototype	off	JS + TS	Class methods should be used instead of "prototype" assignments	Off: not in the Sonar way profile of SonarQube.
sonarjs/max-union-size	off	JS + TS	Union types should not have too many elements	Off: not in the Sonar way profile of SonarQube.
sonarjs/no-return-type-any	off	JS + TS	Primitive return types should be used	Off: not in the Sonar way profile of SonarQube.
sonarjs/deprecation	off	JS + TS	Deprecated APIs should not be used	Off: duplicate of @typescript-eslint/no-deprecated.
sonarjs/no-primitive-wrappers	off	JS + TS	Wrapper objects should not be used for primitive types	Off: duplicate of no-new-wrappers and @typescript-eslint/no-wrapper-object-types.
sonarjs/argument-type	warn	JS + TS	Arguments to built-in functions should match documented types	—
sonarjs/arguments-order	error	JS + TS	Parameters should be passed in the correct order	—
sonarjs/arguments-usage	off	JS + TS	"arguments" should not be accessed directly	Off: not in the Sonar way profile of SonarQube.
sonarjs/function-return-type	warn	JS + TS	Functions should always return the same type	—
sonarjs/no-undefined-argument	warn	JS + TS	"undefined" should not be passed as the value of optional parameters	—
sonarjs/no-undefined-assignment	off	JS + TS	"undefined" should not be assigned	Off: not in the Sonar way profile of SonarQube.
sonarjs/no-useless-intersection	error	JS + TS	Type intersections should use meaningful types	—
sonarjs/null-dereference	error	JS + TS	Properties of variables with "null" or "undefined" values should not be accessed	—
sonarjs/prefer-type-guard	warn	JS + TS	Type predicates should be used	—
sonarjs/public-static-readonly	warn	JS + TS	Public "static" fields should be read-only	—
sonarjs/redundant-type-aliases	warn	JS + TS	Redundant type aliases should not be used	—
sonarjs/use-type-alias	warn	JS + TS	Type aliases should be used	—
sonarjs/void-use	warn	JS + TS	"void" should not be used	Sonar way; replaces the core @typescript-eslint/no-meaningless-void-operator, like SonarQube.
@typescript-eslint/adjacent-overload-signatures	info	TS	Require that function overload signatures be consecutive	—
@typescript-eslint/consistent-generic-constructors	error	TS	Enforce specifying generic type arguments on type annotation or constructor name of a constructor call	—
@typescript-eslint/consistent-type-assertions	error	TS	Enforce consistent usage of type assertions	—
@typescript-eslint/consistent-type-definitions	error	TS	Enforce type definitions to consistently use either interface or type	—
@typescript-eslint/consistent-type-exports	error	TS	Enforce consistent usage of type exports	—
@typescript-eslint/consistent-type-imports	error	TS	Enforce consistent usage of type imports	—
@typescript-eslint/explicit-function-return-type	error	TS	Require explicit return types on functions and class methods	—
@typescript-eslint/explicit-module-boundary-types	off	TS	Require explicit return and argument types on exported functions' and classes' public class methods	Off: duplicate of explicit-function-return-type.
@typescript-eslint/method-signature-style	error, "method"	TS	Enforce using a particular method signature syntax	Custom: foo(): void style; pass members as callbacks through () => api.foo().
@typescript-eslint/no-confusing-non-null-assertion	off	TS	Disallow non-null assertion in locations that may be confusing	Off: no-non-null-assertion forbids every !.
@typescript-eslint/no-confusing-void-expression	error	TS	Require expressions of type void to appear in statement position	—
@typescript-eslint/no-deprecated	warn	TS	Disallow using code marked as @deprecated	Warn: a deprecated API may have no replacement yet.
@typescript-eslint/no-duplicate-enum-values	error	TS	Disallow duplicate enum member values	—
@typescript-eslint/no-duplicate-type-constituents	error	TS	Disallow duplicate constituents of union or intersection types	—
@typescript-eslint/no-empty-interface	off	TS	Disallow the declaration of empty interfaces	Deprecated: replaced by no-empty-object-type.
@typescript-eslint/no-empty-object-type	warn	TS	Disallow accidentally using the "empty object" type	—
@typescript-eslint/no-explicit-any	warn	TS	Disallow the any type	Warn: an any is justified where it is written (off in a library: rules/library). Using an any value stays an error (no-unsafe-*).
@typescript-eslint/no-extra-non-null-assertion	off	TS	Disallow extra non-null assertions	Off: no-non-null-assertion forbids every !.
@typescript-eslint/no-generated-empty-object-type	error	TS	Disallow type operations that resolve to the "empty object" type	—
@typescript-eslint/no-import-type-side-effects	error	TS	Enforce the use of top-level import type qualifier when an import only has specifiers with inline type qualifiers	—
@typescript-eslint/no-inferrable-types	error	TS	Disallow explicit type declarations for variables or parameters initialized to a number, string, or boolean	—
@typescript-eslint/no-invalid-void-type	warn	TS	Disallow void type outside of generic or return types	Warn: a void in a union or a generic is justified where it is written (off in a library: rules/library).
@typescript-eslint/no-meaningless-void-operator	off	TS	Disallow the void operator except when used to discard a value	Off: replaced by sonarjs/void-use, like SonarQube.
@typescript-eslint/no-mixed-enums	error	TS	Disallow enums from having both number and string members	—
@typescript-eslint/no-non-null-asserted-nullish-coalescing	off	TS	Disallow non-null assertions in the left operand of a nullish coalescing operator	Off: no-non-null-assertion forbids every !.
@typescript-eslint/no-non-null-asserted-optional-chain	off	TS	Disallow non-null assertions after an optional chain expression	—
@typescript-eslint/no-non-null-assertion	warn	TS	Disallow non-null assertions using the ! postfix operator	Warn: a value the types cannot prove present.
@typescript-eslint/no-redundant-type-constituents	info	TS	Disallow members of unions and intersections that do nothing or override type information	—
@typescript-eslint/no-restricted-types	error	TS	Disallow certain types	—
@typescript-eslint/no-type-alias	off	TS	Disallow type aliases	Deprecated: replaced by consistent-type-definitions.
@typescript-eslint/no-unnecessary-type-arguments	error	TS	Disallow type arguments that are equal to the default	—
@typescript-eslint/no-unnecessary-type-assertion	error	TS	Disallow type assertions that do not change the type of an expression	—
@typescript-eslint/no-unnecessary-type-constraint	info	TS	Disallow unnecessary constraints on generic types	—
@typescript-eslint/no-unnecessary-type-conversion	info	TS	Disallow conversion idioms when they do not change the type or value of the expression	—
@typescript-eslint/no-unnecessary-type-parameters	error	TS	Disallow type parameters that aren't used multiple times	—
@typescript-eslint/no-unsafe-argument	error	TS	Disallow calling a function with a value with type any	Using an any value breaks the typing: an error, never disabled.
@typescript-eslint/no-unsafe-assignment	error	TS	Disallow assigning a value with type any to variables and properties	Using an any value breaks the typing: an error, never disabled.
@typescript-eslint/no-unsafe-call	error	TS	Disallow calling a value with type any	Using an any value breaks the typing: an error, never disabled.
@typescript-eslint/no-unsafe-declaration-merging	error	TS	Disallow unsafe declaration merging	—
@typescript-eslint/no-unsafe-enum-assignment	error	TS	Disallow assigning non-enum values to enum typed locations	—
@typescript-eslint/no-unsafe-function-type	warn	TS	Disallow using the unsafe built-in Function type	Warn: generic or external code sometimes needs it.
@typescript-eslint/no-unsafe-member-access	error	TS	Disallow member access on a value with type any	Using an any value breaks the typing: an error, never disabled.
@typescript-eslint/no-unsafe-return	error	TS	Disallow returning a value with type any from a function	Using an any value breaks the typing: an error, never disabled.
@typescript-eslint/no-unsafe-type-assertion	warn	TS	Disallow type assertions that narrow a type	Warn: narrowing an external type sometimes needs an assertion.
@typescript-eslint/no-wrapper-object-types	error	TS	Disallow using confusing built-in primitive class wrappers	—
@typescript-eslint/non-nullable-type-assertion-style	off	TS	Enforce non-null assertions over explicit type assertions	Off: asks for x!, forbidden by no-non-null-assertion.
@typescript-eslint/prefer-enum-initializers	info	TS	Require each enum member value to be explicitly initialized	—
@typescript-eslint/prefer-function-type	error	TS	Enforce using function types instead of interfaces with call signatures	—
@typescript-eslint/prefer-literal-enum-member	info	TS	Require all enum members to be literal values	—
@typescript-eslint/prefer-readonly	error	TS	Require private members to be marked as readonly if they're never modified outside of the constructor	—
@typescript-eslint/prefer-readonly-parameter-types	warn, {"ignoreInferredTypes":true,"treatMethodsAsReadonly":true…	TS	Require function parameters to be typed as readonly to prevent accidental mutation of inputs	Custom: a utility never mutates its arguments; functions and DOM/runtime types (live objects) are exempt. Warn: external types (DOM, libraries) are not deeply readonly.
@typescript-eslint/prefer-return-this-type	error	TS	Enforce that this is used when only this type is returned	—
@typescript-eslint/strict-void-return	error	TS	Disallow passing a value-returning function in a position accepting a void function	—
@typescript-eslint/typedef	off	TS	Require type annotations in certain places	Deprecated: no replacement.
@typescript-eslint/unified-signatures	info	TS	Disallow two overloads that could be unified into one with a union or an optional/rest parameter	—