ReSharper 2022.1 Help

Code Inspections in TypeScript

In TypeScript, ReSharper 2022.1 provides two kinds of code inspections: 141 inspections that detect errors such as broken syntax, unresolved symbols, compiler errors, and so on (you cannot configure or disable any of these inspections), and 51 proprietary code inspections, any of which you can disable or change its severity level.
These code inspections help you detect code issues in design time in all open files, and additionally they allow you to find code issues in specific scope.

Configurable TypeScript inspections are listed below, grouped by their categories.

Common Practices and Code Improvements (4 inspections)

This category groups inspections that hunt for medium severity issues that mainly affect code readability.

Inspection


ID


EditorConfig property

Default severity

Constructor of an abstract class can be made protected


AbstractClassConstructorCanBeMadeProtected


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Hint

Introducing variable will allow to apply type guard


IntroduceVariableToApplyGuard


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Hint

Private class field can be made readonly


PrivateVariableCanBeMadeReadonly


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Hint

String literal usage allows creating specialized overload


CreateSpecializedOverload


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Hint

Language Usage Opportunities (9 inspections)

This category includes code inspections, mostly with the suggestion severity level, which notify you when more advanced language constructs can be used. These inspections detect syntax of outdated language versions and suggest using features from more modern language versions. For most of the supported languages, language version can be detected automatically or set manually.

Inspection


ID


EditorConfig property

Default severity

AMD module may be converted to external module


AmdExternalModule


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Suggestion

Class emulation may be converted to class


Class


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Suggestion

CommonJs module may be converted to external module


CommonJsExternalModule


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Suggestion

Function expression may be converted to lambda expression


Lambda


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Suggestion

Immediately-invoked function expression may be converted to internal module


InternalModule


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Suggestion

Invocation of parent class may be converted to super call


SuperCall


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Suggestion

Member assigned by a function may be converted to function member


MethodSafeThis


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Suggestion

Possible overloads may be inferred by function body


OverloadSignatureInferring


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Hint

Use 'as' operator instead of type assertion


UseAsInsteadOfTypeCast


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Hint

Potential Code Quality Issues (15 inspections)

This category includes inspections that detect critical issues (code smells), mostly with Error or Warning level. This category also includes inspections that ensure localization assistance.

Inspection


ID


EditorConfig property

Default severity

Cannot resolve, probably symbol is located in inaccessible module


TsResolvedFromInaccessibleModule


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Error

Check 'amd-dependency' the same way as require() argument


AmdDependencyPathProblem


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Disabled

Duplicate identifier


DuplicateIdentifierError


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Error

Empty return value for type-annotated function


EmptyReturnValueForTypeAnnotatedFunction


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Warning

Exported entity uses a private entity


DeclarationVisibilityError


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Error

'Implicit any' inspection when NoImplicitAny is set


ImplicitAnyError


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Error

More specific signature follows less specific


MoreSpecificSignatureAfterLessSpecific


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Warning

Overload is less specific than the main signature


LessSpecificOverloadThanMainSignature


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Warning

Parameter-property value assigned inside constructor won't be assigned to class property


AssignedValueWontBeAssignedToCorrespondingField


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Warning

Suspicious 'instanceof' check


SuspiciousInstanceofCheck


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Warning

Suspicious 'this' usage in context of local function inside class member


SuspiciousThisUsage


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Warning

Suspicious 'typeof' check


SuspiciousTypeofCheck


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Warning

Type parameter hides type parameter declared in outer scope


TypeParameterHidesTypeParamFromOuterScope


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Warning

Use of possibly unassigned property in a static initializer


UseOfPossiblyUnassignedProperty


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Warning

Use of undeclared variable


TsNotResolved


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Error

Redundancies in Code (9 inspections)

Code inspections in this category look for redundancies and dead code, which affect code readability and style, and could be safely removed. Some code redundancies cannot be fixed automatically, and quick-fixes for them are performed in the interactive mode, requiring the user input. But the majority of the redundancies can be fixed without user interaction, using either fix in scope or code cleanup.

Inspection


ID


EditorConfig property

Default severity

Comparison of boolean with boolean value is equivalent to value or negated value


RedundantComparisonWithBoolean


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Warning

Double negation of boolean is redundant


DoubleNegationOfBoolean


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Warning

Duplicate reference comment is redundant


DuplicateReferenceComment


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Warning

Redundant parent type specification in extends/implements


RedundantParentTypeDeclaration


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Warning

Redundant qualifier


RedundantQualifier


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Warning

Reference comment creates cyclic dependency


CyclicReferenceComment


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Disabled

Ternary operator may be replaced by it's condition


TernaryCanBeReplacedByItsCondition


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Warning

Type cast is redundant: expression is always of provided type


RedundantTypeCast


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Warning

Type cast is redundant: expression is of a structurally compatible type


RedundantTypeCastStructural


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Warning

Redundancies in Symbol Declarations (6 inspections)

This category includes code inspections, mostly with the warning severity level, which detect empty and unused symbol declarations.

Inspection


ID


EditorConfig property

Default severity

Parameter doesn't participate in the main signature


ParameterDoesntMakeAnySense


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Warning

Redundant empty constructor without parameters


RedundantEmptyConstructor


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Warning

Same item is imported twice with different names


SameImportsWithDifferentName


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Warning

Type guard definitely produces 'never' type for the variable


TypeGuardProducesNeverType


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Warning

Type guard doesn't affect variable's type in any way


TypeGuardDoesntAffectAnything


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Warning

Unused local import


UnusedLocalImport


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Warning

Spelling issues (3 inspections)

These inspections detect typos in various contexts.

Inspection


ID


EditorConfig property

Default severity

Typo in comment


CommentTypo


resharper_comment_typo_highlighting

Suggestion

Typo in identifier


IdentifierTypo


resharper_identifier_typo_highlighting

Suggestion

Typo in string literal


StringLiteralTypo


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Suggestion

Syntax Style (5 inspections)

Inspections in this category detect violations of code syntax styles. In contrast to most of other code inspections, these inspections can either detect the same code construct as a code issue or not depending on the corresponding code style rule configured on the Code Editing | TypeScript | Syntax Style page of ReSharper options (Alt+R, O). You can also fix issues that these inspection detect using code cleanup.

Inspection


ID


EditorConfig property

Default severity

Element has implicit 'any' type


ImplicitAnyTypeWarning


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Warning

Non-compliant path style inside 'require'


WrongRequireRelativePath


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Hint

Non-compliant 'public' modifier or its absence


WrongPublicModifierSpecification


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Hint

Type of variable may be specified explicitly


SpecifyVariableTypeExplicitly


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Hint

Type specification is redundant, because variable type is contextually determined from the type of assigned value


RedundantVariableTypeSpecification


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Hint

Last modified: 30 March 2022