ReSharper 2025.1 Help

Code Inspections in TypeScript

In TypeScript, ReSharper 2025.1 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 55 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
resharper_abstract_class_constructor_can_be_made_protected_highlighting

Hint

Introducing variable will allow to apply type guard


IntroduceVariableToApplyGuard
resharper_introduce_variable_to_apply_guard_highlighting

Hint

Private class field can be made readonly


PrivateVariableCanBeMadeReadonly
resharper_private_variable_can_be_made_readonly_highlighting

Hint

String literal usage allows creating specialized overload


CreateSpecializedOverload
resharper_create_specialized_overload_highlighting

Hint

Grammar Issues (4 inspections)

Inspections in this category report grammar issues in string literals and documentation comments.

Inspection
ID
EditorConfig property

Default severity

Grammar error in comment


GrammarMistakeInComment
resharper_grammar_mistake_in_comment_highlighting

Suggestion

Grammar error in markup attribute value


GrammarMistakeInMarkupAttribute
resharper_grammar_mistake_in_markup_attribute_highlighting

Suggestion

Grammar error in markup text


GrammarMistakeInMarkupText
resharper_grammar_mistake_in_markup_text_highlighting

Suggestion

Grammar error in string literal


GrammarMistakeInStringLiteral
resharper_grammar_mistake_in_string_literal_highlighting

Disabled

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 These inspections detect syntax of outdated language versions and suggest using features from more modern language versions.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 can be converted to external module


AmdExternalModule
resharper_amd_external_module_highlighting

Suggestion

Class emulation can be converted to class


Class
resharper_class_highlighting

Suggestion

CommonJs module can be converted to external module


CommonJsExternalModule
resharper_common_js_external_module_highlighting

Suggestion

Function expression can be converted to lambda expression


Lambda
resharper_lambda_highlighting

Suggestion

Immediately-invoked function expression can be converted to internal module


InternalModule
resharper_internal_module_highlighting

Suggestion

Invocation of parent class can be converted to super call


SuperCall
resharper_super_call_highlighting

Suggestion

Member assigned by a function can be converted to function member


MethodSafeThis
resharper_method_safe_this_highlighting

Suggestion

Possible overloads can be inferred by function body


OverloadSignatureInferring
resharper_overload_signature_inferring_highlighting

Hint

Use 'as' operator instead of type assertion


UseAsInsteadOfTypeCast
resharper_use_as_instead_of_type_cast_highlighting

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
resharper_ts_resolved_from_inaccessible_module_highlighting

Error

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


AmdDependencyPathProblem
resharper_amd_dependency_path_problem_highlighting

Disabled

Duplicate identifier


DuplicateIdentifierError
resharper_duplicate_identifier_error_highlighting

Error

Empty return value for type-annotated function


EmptyReturnValueForTypeAnnotatedFunction
resharper_empty_return_value_for_type_annotated_function_highlighting

Warning

Exported entity uses a private entity


DeclarationVisibilityError
resharper_declaration_visibility_error_highlighting

Error

'Implicit any' inspection when NoImplicitAny is set


ImplicitAnyError
resharper_implicit_any_error_highlighting

Error

More specific signature follows less specific


MoreSpecificSignatureAfterLessSpecific
resharper_more_specific_signature_after_less_specific_highlighting

Warning

Overload is less specific than the main signature


LessSpecificOverloadThanMainSignature
resharper_less_specific_overload_than_main_signature_highlighting

Warning

Parameter-property value assigned inside constructor will not be assigned to class property


AssignedValueWontBeAssignedToCorrespondingField
resharper_assigned_value_wont_be_assigned_to_corresponding_field_highlighting

Warning

Suspicious 'instanceof' check


SuspiciousInstanceofCheck
resharper_suspicious_instanceof_check_highlighting

Warning

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


SuspiciousThisUsage
resharper_suspicious_this_usage_highlighting

Warning

Suspicious 'typeof' check


SuspiciousTypeofCheck
resharper_suspicious_typeof_check_highlighting

Warning

Type parameter hides type parameter declared in outer scope


TypeParameterHidesTypeParamFromOuterScope
resharper_type_parameter_hides_type_param_from_outer_scope_highlighting

Warning

Use of possibly unassigned property in a static initializer


UseOfPossiblyUnassignedProperty
resharper_use_of_possibly_unassigned_property_highlighting

Warning

Use of undeclared variable


TsNotResolved
resharper_ts_not_resolved_highlighting

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
resharper_redundant_comparison_with_boolean_highlighting

Warning

Double negation of boolean is redundant


DoubleNegationOfBoolean
resharper_double_negation_of_boolean_highlighting

Warning

Duplicate reference comment is redundant


DuplicateReferenceComment
resharper_duplicate_reference_comment_highlighting

Warning

Redundant parent type specification in extends/implements


RedundantParentTypeDeclaration
resharper_redundant_parent_type_declaration_highlighting

Warning

Redundant qualifier


RedundantQualifier
resharper_redundant_qualifier_highlighting

Warning

Reference comment creates cyclic dependency


CyclicReferenceComment
resharper_cyclic_reference_comment_highlighting

Disabled

Ternary operator can be replaced with its condition


TernaryCanBeReplacedByItsCondition
resharper_ternary_can_be_replaced_by_its_condition_highlighting

Warning

Type cast is redundant: expression is always of provided type


RedundantTypeCast
resharper_redundant_type_cast_highlighting

Warning

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


RedundantTypeCastStructural
resharper_redundant_type_cast_structural_highlighting

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 is not a part of the main signature


ParameterDoesntMakeAnySense
resharper_parameter_doesnt_make_any_sense_highlighting

Warning

Redundant empty constructor without parameters


RedundantEmptyConstructor
resharper_redundant_empty_constructor_highlighting

Warning

Same item is imported twice with different names


SameImportsWithDifferentName
resharper_same_imports_with_different_name_highlighting

Warning

Type guard definitely produces 'never' type for the variable


TypeGuardProducesNeverType
resharper_type_guard_produces_never_type_highlighting

Warning

Type guard does not affect variable's type in any way


TypeGuardDoesntAffectAnything
resharper_type_guard_doesnt_affect_anything_highlighting

Warning

Unused local import


UnusedLocalImport
resharper_unused_local_import_highlighting

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
resharper_string_literal_typo_highlighting

Suggestion

Syntax Style (5 inspections)

Inspections in this category detect violations of code syntax styles. In contrast to most 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
resharper_implicit_any_type_warning_highlighting

Warning

Non-compliant path style inside 'require'


WrongRequireRelativePath
resharper_wrong_require_relative_path_highlighting

Hint

Non-compliant 'public' modifier or its absence


WrongPublicModifierSpecification
resharper_wrong_public_modifier_specification_highlighting

Hint

Type of variable can be specified explicitly


SpecifyVariableTypeExplicitly
resharper_specify_variable_type_explicitly_highlighting

Hint

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


RedundantVariableTypeSpecification
resharper_redundant_variable_type_specification_highlighting

Hint

Last modified: 31 March 2025