ReSharper 2018.2 Help

Code Inspections in JavaScript

In JavaScript, ReSharper 2018.2 provides two kinds of code inspections: 4 inspections that detect errors such as broken syntax, unresolved symbols, compiler errors, etc. (you cannot configure or disable any of these inspections), and 112 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 JavaScript inspections are listed below, grouped by their categories.

Code 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] | Code Style page of ReSharper options. You can also fix issues that these inspection detect, using code cleanup.

Inspection

ID

EditorConfig property

Default severity

Function is used before it is declared

FunctionsUsedBeforeDeclared

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Disabled

Function is used outside of scope which it is declared

FunctionUsedOutOfScope

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Warning

Non-compliant quotes around string literal

StringLiteralWrongQuotes

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Hint

Variable is used in inner scope before it is declared

VariableUsedInInnerScopeBeforeDeclared

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Warning

Variable is used outside of scope which it is declared

VariableUsedOutOfScope

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Warning

Common Practices and Code Improvements (3 inspections)

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

Inspection

ID

EditorConfig property

Default severity

Join local variable declaration and assignment

JoinDeclarationAndInitializerJs

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Suggestion

Statement termination doesn't match code style

StatementTermination

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Warning

Use of future reserved word

UsingOfReservedWord

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Warning

Constraints Violations (1 inspection)

This category includes code inspections, mostly with the warning severity level, which detect violations related to symbol attributes, including ReSharper's code annotations, and other similar issues.

Inspection

ID

EditorConfig property

Default severity

Inconsistent Naming

InconsistentNaming

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Warning

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

A serie of undefined-checks for properties may be replaced by a destructuring

ReplaceUndefinedCheckingSeriesWithObjectDestructuring

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Hint

Intermediate local variable is redundant and may be safely inlined

RedundantIntermediateVariable

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Hint

Intermediate local variable is redundant because it may be replaced with a destructuring swap expression

ReplaceWithDestructuringSwap

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Hint

Local variable can be safely moved to inner block

VariableCanBeMovedToInnerBlock

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Hint

String concatenation may be converted to template string

StringConcatenationToTemplateString

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Hint

Subsequent indexers in object literal fields may be simplified using a destructuring

ReplaceIndicingWithShortHandPropertiesAfterDestructuring

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Hint

Subsequent indexers may be replaced by a destructuring declaration or assignment

ReplaceIndicingWithArrayDestructuring

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Hint

'var' variable can be made 'let' variable

VariableCanBeMadeLet

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Hint

Variable can be made constant

VariableCanBeMadeConst

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Hint

Potential Code Quality Issues (68 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

'?:' expression has identical true and false branches

ConditionalTernaryEqualBranch

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Warning

A trailing element of an array is elided

ElidedTrailingElement

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Warning

Assignment to a variable inside a conditional statement

AssignmentInConditionExpression

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Warning

Assignment to an implicitly declared global variable

AssignToImplicitGlobalInFunctionScope

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Warning

Assignment to constant

AssignToConstant

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Error

Cannot resolve symbol

NotResolved

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Warning

Closure on a variable modified in loop of outer scope

ClosureOnModifiedVariable

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Warning

Comma is expected in object literal

ObjectLiteralsAreNotCommaFree

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Error

Comma is not valid here

CommaNotValidHere

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Error

Comparison of 'typeof' expression with incorrect value

IncorrectOperandInTypeOfComparison

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Warning

Condition is always constant

ConditionIsAlwaysConst

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Warning

Constructor call is not used or possibly used for side-effects

ConstructorCallNotUsed

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Warning

Declaration hides another declaration from an outer scope

DeclarationHides

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Hint

Duplicate property declaration

DuplicatingPropertyDeclaration

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Warning

Duplicate switch label

DuplicatingSwitchLabel

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Warning

ECMAScript 2015 feature usage when in ES 5 or lower

Es6Feature

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Error

ECMAScript 2016 feature usage when in ES 2015 or lower

Es7Feature

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Error

Error in Xml doc comment reference

ErrorInXmlDocReference

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Error

Experimental feature usage when language level set to stable

ExperimentalFeature

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Error

Expression is always constant

ExpressionIsAlwaysConst

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Warning

Expression is expected after 'throw' statement

ThrowMustBeFollowedByExpression

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Error

Extending prototype of native object

NativeTypePrototypeExtending

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Warning

Heuristically unreachable code

HeuristicallyUnreachableCode

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Warning

Illegal syntax in XML code comment

XmlDocCommentSyntaxProblem

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Warning

'import' keyword is not allowed here.

ImportKeywordNotWithInvocation

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Error

Inconsistent function returns

InconsistentFunctionReturns

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Warning

Invalid JSON syntax

InvalidJsonSyntax

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Error

Invocation of non-function expression

InvocationOfNonFunction

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Warning

Invoked expression is not a function value

InvokedExpressionMaybeNonFunction

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Warning

JSON validation failed

JsonValidationFailed

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Error

Lexical declaration can only be declared inside a block.

LexicalDeclarationNeedsBlock

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Error

Local function is redefined later

LocalFunctionRedefinedLater

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Warning

L-value expected error

LValueIsExpected

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Error

Misuse of 'this' qualifier in inner function

MisuseOfOwnerFunctionThis

resharper_misuse_of_owner_function_this_highlighting

Warning

Multiple declarations in 'for in' error

MultipleDeclarationsInForeach

resharper_multiple_declarations_in_foreach_highlighting

Error

Non-assigned constant

NonAssignedConstant

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Error

Non-parenthesized object destructuring assignment cannot be used in an expression statement

ObjectDestructuringWithoutParentheses

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Error

Not all code paths return a value

NotAllPathsReturnValue

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Warning

Object property declaration is expected

EmptyObjectPropertyDeclaration

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Error

Overwriting prototype of native object

NativeTypePrototypeOverwriting

resharper_native_type_prototype_overwriting_highlighting

Warning

Parameter name 'arguments' clashes with pre-defined JS function-scope variable

FunctionParameterNamedArguments

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Warning

Parameter value is not used

ParameterValueIsNotUsed

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Warning

Path for reference comment not found

JsPathNotFound

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Error

Possible mistake: ambiguous lambda block and object literal

SuspiciousLambdaBlock

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Warning

Property getter cannot have parameters

PropertyGetterCannotHaveParameters

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Error

Property setter must have a single parameter

PropertySetterMustHaveSingleParameter

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Error

Qualifier can be 'null' or 'undefined'

QualifiedExpressionMaybeNull

resharper_qualified_expression_maybe_null_highlighting

Warning

Qualifier is 'null' or 'undefined'

QualifiedExpressionIsNull

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Warning

Redeclaration of let/const

BlockScopeRedeclaration

resharper_block_scope_redeclaration_highlighting

Error

Return statement with a value in the global scope

ReturnFromGlobalScopetWithValue

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Warning

Similar expressions comparison

SimilarExpressionsComparison

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Warning

Statement is possibly incorrectly broken by a newline

PossiblyIncorrectlyBrokenStatement

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Warning

'super' must be called before accessing 'this' in the constructor of a derived class.

SuperCallProhibitsThis

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Error

Suspicious expression statement

WrongExpressionStatement

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Warning

There is no .hasOwnProperty() check in a body of 'for in' loop. This will cause an enumeration of prototype properties

MissingHasOwnPropertyInForeach

resharper_missing_has_own_property_in_foreach_highlighting

Warning

Trailing redundant comma in object properties list may be error

UnsafeCommaInObjectPropertiesList

resharper_unsafe_comma_in_object_properties_list_highlighting

Warning

Triple-slash directives are only valid at the top of the file

IncorrectTripleSlashLocation

resharper_incorrect_triple_slash_location_highlighting

Warning

Usage of possibly unassigned local variable

UsageOfPossiblyUnassignedValue

resharper_usage_of_possibly_unassigned_value_highlighting

Warning

Usage of unassigned local variable

UsageOfDefinitelyUnassignedValue

resharper_usage_of_definitely_unassigned_value_highlighting

Warning

Use 'break' or 'continue' outside of loop body

JumpMustBeInLoop

resharper_jump_must_be_in_loop_highlighting

Warning

Use of expression after break or continue

LabelOrSemicolonExpected

resharper_label_or_semicolon_expected_highlighting

Error

Use of implicitly declared global variable

UseOfImplicitGlobalInFunctionScope

resharper_use_of_implicit_global_in_function_scope_highlighting

Warning

Use of possibly unassigned property or global variable

PossiblyUnassignedProperty

resharper_possibly_unassigned_property_highlighting

Hint

Use of 'this' in global context

ThisInGlobalContext

resharper_this_in_global_context_highlighting

Warning

Using of 'arguments.caller' and 'arguments.callee'

CallerCalleeUsing

resharper_caller_callee_using_highlighting

Warning

Using of coerced equality (using of coerced equality operator with 'null' or 'undefined')

CoercedEqualsUsingWithNullUndefined

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Disabled

Using of coerced equality (using of coerced equality operator)

CoercedEqualsUsing

resharper_coerced_equals_using_highlighting

Warning

Variable is used before it is declared

VariableUsedBeforeDeclared

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Warning

Redundancies in Code (4 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

Assigned value is never used

AssignedValueIsNeverUsed

resharper_assigned_value_is_never_used_highlighting

Warning

Redundant block

RedundantBlock

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Warning

Redundant empty finally block

RedundantEmptyFinallyBlock

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Warning

Unreachable code

JsUnreachableCode

resharper_js_unreachable_code_highlighting

Warning

Redundancies in Symbol Declarations (10 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

Assignment of a local variable to itself is redundant

SameVariableAssignment

resharper_same_variable_assignment_highlighting

Warning

Duplicate local declaration

DuplicatingLocalDeclaration

resharper_duplicating_local_declaration_highlighting

Warning

Redundant 'else' block

RedundantElseBlock

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Warning

Redundant local class name

RedundantLocalClassName

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Hint

Redundant local function name

RedundantLocalFunctionName

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Hint

Type or member is never used (non-private accessibility)

UnusedMember.Global

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Suggestion

Unused local variable / function / class

UnusedLocals

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Warning

Unused parameter

UnusedParameter

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Warning

Unused parameter of inherited member

UnusedInheritedParameter

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Hint

Unused property or function

UnusedProperty

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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

resharper_string_literal_typo_highlighting

Suggestion

Strict mode violations (9 inspections)

 

Inspection

ID

EditorConfig property

Default severity

Calling 'delete' on non-qualified identifier in 'strict mode'

DeletingNonQualifiedReference

resharper_deleting_non_qualified_reference_highlighting

Error

Duplicate parameter declaration in 'strict mode'

DuplicatingParameterDeclarationError

resharper_duplicating_parameter_declaration_error_highlighting

Error

Duplicate property declaration in 'strict mode'

DuplicatingPropertyDeclarationError

resharper_duplicating_property_declaration_error_highlighting

Error

Octal literals and escape sequences using in 'strict mode'

OctalLiteralsNotAllowedError

resharper_octal_literals_not_allowed_error_highlighting

Error

Using of 'arguments.caller' and 'arguments.callee' in 'strict mode'

CallerCalleeUsingError

resharper_caller_callee_using_error_highlighting

Error

Using of 'eval'/'arguments' name in 'strict mode'

EvalArgumentsNameError

resharper_eval_arguments_name_error_highlighting

Error

Using of future reserved keywords in 'strict mode'

UsingOfReservedWordError

resharper_using_of_reserved_word_error_highlighting

Error

Using of undeclared global variable

UndeclaredGlobalVariableUsing

resharper_undeclared_global_variable_using_highlighting

Warning

Using of 'with' statements in 'strict mode'

WithStatementUsingError

resharper_with_statement_using_error_highlighting

Error

Last modified: 28 November 2018