ReSharper 2020.2 Help

Code Inspections in TypeScript

In TypeScript, ReSharper 2020.2 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
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

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 These inspections detect syntax of outdated language versions and suggest using features from more modern language versions.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
resharper_amd_external_module_highlighting
Suggestion
Class emulation may be converted to class
Class
resharper_class_highlighting
Suggestion
CommonJs module may be converted to external module
CommonJsExternalModule
resharper_common_js_external_module_highlighting
Suggestion
Function expression may be converted to lambda expression
Lambda
resharper_lambda_highlighting
Suggestion
Immediately-invoked function expression may be converted to internal module
InternalModule
resharper_internal_module_highlighting
Suggestion
Invocation of parent class may be converted to super call
SuperCall
resharper_super_call_highlighting
Suggestion
Member assigned by a function may be converted to function member
MethodSafeThis
resharper_method_safe_this_highlighting
Suggestion
Possible overloads may 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 won't 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 may be replaced by it's 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 doesn't participate in 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 doesn't 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 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 | [Language] | 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 may 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 assigned value
RedundantVariableTypeSpecification
resharper_redundant_variable_type_specification_highlighting
Hint
Last modified: 13 August 2020