Rules

Typing mistakes and misunderstandings about where semicolons are required can lead to semicolons that are unnecessary. While not technically an error, extra semicolons can cause confusion when reading code.

noMultipleSpacesInRegularExpressionLiteralsrecommended

Disallow unclear usage of multiple space characters in regular expression literals

noUselessCatchrecommended

Disallow unnecessary catch clauses.

noUselessConstructorrecommended

Disallow unnecessary constructors.

noUselessFragments

Disallow unnecessary fragments

noUselessLabelrecommended

Disallow unnecessary labels.

noUselessRenamerecommended

Disallow renaming import, export, and destructured assignments to the same name.

noUselessSwitchCaserecommended

Disallow useless case in switch statements.

noUselessTypeConstraintrecommended

Disallow using any or unknown as type constraint.

noWithrecommended

Disallow with statements in non-strict contexts.

useFlatMaprecommended

Promotes the use of .flatMap() when map().flat() are used together.

useOptionalChainrecommended

Enforce using concise optional chain instead of chained logical expressions.

useSimplifiedLogicExpression

Discard redundant terms from logical expressions.

Correctness

Rules that detect code that is guaranteed to be incorrect or useless.

noChildrenProprecommended

Prevent passing of children as props.

noConstAssignrecommended

Prevents from having const variables being re-assigned.

noConstructorReturnrecommended

Disallow returning a value from a constructor.

noEmptyPatternrecommended

Disallows empty destructuring patterns.

noGlobalObjectCallsrecommended

Disallow calling global object properties as functions

noInnerDeclarationsrecommended

Disallow function and var declarations that are accessible outside their block.

noInvalidConstructorSuperrecommended

Prevents the incorrect use of super() inside classes. It also checks whether a call super() is missing from classes that extends other constructors.

noNewSymbolrecommended

Disallow new operators with the Symbol object

noPrecisionLossrecommended

Disallow literal numbers that lose precision

noRenderReturnValuerecommended

Prevent the usage of the return value of React.render.

noSetterReturnrecommended

Disallow returning a value from a setter

noStringCaseMismatchrecommended

Disallow comparison of expressions modifying the string case with non-compliant value.

noSwitchDeclarationsrecommended

Disallow lexical declarations in switch clauses.

noUndeclaredVariables

Prevents the usage of variables that haven’t been declared inside the document

noUnnecessaryContinuerecommended

Avoid using unnecessary continue.

noUnreachablerecommended

Disallow unreachable code

noUnreachableSuperrecommended

Ensures the super() constructor is called exactly once on every code path in a class constructor before this is accessed if the class has a superclass

noUnsafeFinallyrecommended

Disallow control flow statements in finally blocks.

noUnsafeOptionalChainingrecommended

Disallow the use of optional chaining in contexts where the undefined value is not allowed.

noUnusedLabelsrecommended

Disallow unused labels.

noUnusedVariables

Disallow unused variables.

noVoidElementsWithChildrenrecommended

This rules prevents void elements (AKA self-closing elements) from having children.

noVoidTypeReturnrecommended

Disallow returning a value from a function with the return type ‘void’

useValidForDirectionrecommended

Enforce “for” loop update clause moving the counter in the right direction.

useYieldrecommended

Require generator functions to contain yield.

Performance

Rules catching ways your code could be written to run faster, or generally be more efficient.

noDeleterecommended

Disallow the use of the delete operator.

Security

Rules that detect potential security flaws.

noDangerouslySetInnerHtmlrecommended

Prevent the usage of dangerous JSX props

noDangerouslySetInnerHtmlWithChildrenrecommended

Report when a DOM element or a component uses both children and dangerouslySetInnerHTML prop.

Style

Rules enforcing a consistent and idiomatic way of writing your code.

noArgumentsrecommended

Disallow the use of arguments

noCommaOperatorrecommended

Disallow comma operator.

noImplicitBoolean

Disallow implicit true values on JSX boolean attributes

noInferrableTypesrecommended

Disallow type annotations for variables, parameters, and class properties initialized with a literal expression.

noNamespace

Disallow the use of TypeScript’s namespaces.

noNegationElse

Disallow negation in the condition of an if statement if it has an else clause

noNonNullAssertionrecommended

Disallow non-null assertions using the ! postfix operator.

noParameterAssignrecommended

Disallow reassigning function parameters.

noParameterProperties

Disallow the use of parameter properties in class constructors.

noRestrictedGlobals

This rule allows you to specify global variable names that you don’t want to use in your application.

noShoutyConstants

Disallow the use of constants which its value is the upper-case version of its name.

noUnusedTemplateLiteralrecommended

Disallow template literals if interpolation and special-character handling are not needed

noVarrecommended

Disallow the use of var

useBlockStatements

Requires following curly brace conventions. JavaScript allows the omission of curly braces when a block contains only one statement. However, it is considered by many to be best practice to never omit curly braces around blocks, even when they are optional, because it can lead to bugs and reduces code clarity.

useConstrecommended

Require const declarations for variables that are never reassigned after declared.

useDefaultParameterLastrecommended

Enforce default function parameters and optional parameters to be last.

useEnumInitializersrecommended

Require that each enum member value be explicitly initialized.

useExponentiationOperator

Disallow the use of Math.pow in favor of the ** operator.

useFragmentSyntax

This rule enforces the use of <>…</> over <Fragment>…</Fragment>.

useNumericLiteralsrecommended

Disallow parseInt() and Number.parseInt() in favor of binary, octal, and hexadecimal literals

useSelfClosingElementsrecommended

Prevent extra closing tags for components without children

useShorthandArrayType

When expressing array types, this rule promotes the usage of T[] shorthand instead of Array<T>.

useSingleCaseStatement

Enforces switch clauses have a single statement, emits a quick fix wrapping the statements in a block.

useSingleVarDeclaratorrecommended

Disallow multiple variable declarations in the same variable statement

useTemplaterecommended

Template literals are preferred over string concatenation.

useWhilerecommended

Enforce the use of while loops instead of for loops when the initializer and update expressions are not needed

Suspicious

Rules that detect code that is likely to be incorrect or useless.

noArrayIndexKeyrecommended

Discourage the usage of Array index in keys.

noAssignInExpressionsrecommended

Disallow assignments in expressions.

noAsyncPromiseExecutorrecommended

Disallows using an async function as a Promise executor.

noCatchAssignrecommended

Disallow reassigning exceptions in catch clauses.

noClassAssignrecommended

Disallow reassigning class members.

noCommentTextrecommended

Prevent comments from being inserted as text nodes

noCompareNegZerorecommended

Disallow comparing against -0

noConfusingLabelsrecommended

Disallow labeled statements that are not loops.

noConstEnumrecommended

Disallow TypeScript const enum

noDebuggerrecommended

Disallow the use of debugger

noDoubleEqualsrecommended

Require the use of === and !==

noDuplicateCaserecommended

Disallow duplicate case labels. If a switch statement has duplicate test expressions in case clauses, it is likely that a programmer copied a case clause but forgot to change the test expression.

noDuplicateClassMembersrecommended

Disallow duplicate class members.

noDuplicateObjectKeysrecommended

Prevents object literals having more than one property declaration for the same name. If an object property with the same name is defined multiple times (except when combining a getter with a setter), only the last definition makes it into the object and previous definitions are ignored, which is likely a mistake.

noDuplicateParametersrecommended

Disallow duplicate function parameter name.

noEmptyInterfacerecommended

Disallow the declaration of empty interfaces.

noExplicitAnyrecommended

Disallow the any type usage.

noExtraNonNullAssertionrecommended

Prevents the wrong usage of the non-null assertion operator (!) in TypeScript files.

noFunctionAssignrecommended

Disallow reassigning function declarations.

noImportAssignrecommended

Disallow assigning to imported bindings

noLabelVarrecommended

Disallow labels that share a name with a variable

noPrototypeBuiltinsrecommended

Disallow direct use of Object.prototype builtins.

noRedeclarerecommended

Disallow variable, function, class, and type redeclarations in the same scope.

noRedundantUseStrict

Prevents from having redundant “use strict”.

noSelfComparerecommended

Disallow comparisons where both sides are exactly the same.

noShadowRestrictedNamesrecommended

Disallow identifiers from shadowing restricted names.

noSparseArrayrecommended

Disallow sparse arrays

noUnsafeNegationrecommended

Disallow using unsafe negation.

useDefaultSwitchClauseLastrecommended

Enforce default clauses in switch statements to be last

useNamespaceKeywordrecommended

Require using the namespace keyword over the module keyword to declare TypeScript namespaces.

useValidTypeofrecommended

This rule verifies the result of typeof $expr unary expressions is being compared to valid values, either string literals containing valid type names or other typeof expressions

Nursery

New rules that are still under development.

Nursery rules require explicit opt-in via configuration on stable versions because they may still have bugs or performance problems. They are enabled by default on nightly builds, but as they are unstable their diagnostic severity may be set to either error or warning, depending on whether we intend for the rule to be recommended or not when it eventually gets stabilized. Nursery rules get promoted to other groups once they become stable or may be removed.

Rules that belong to this group are not subject to semantic version.