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.
Common Practices and Code Improvements (3 inspections)
This category groups inspections that hunt for medium severity issues that mainly affect code readability.
Join local variable declaration and assignment
Statement termination doesn't match code style
Use of future reserved word
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.
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 These inspections detect syntax of outdated language versions and suggest using features from more modern language versions.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.
A series of undefined-checks for properties can be replaced with destructuring
Intermediate local variable is redundant and can be safely inlined
Intermediate local variable is redundant because it can be replaced with a destructuring swap expression
Local variable can be safely moved to inner block
String concatenation can be converted to a template string
Subsequent indexers can be replaced by a destructuring declaration or assignment
Subsequent indexers in object literal fields can be simplified with destructuring
'var' variable can be made 'let' variable
Variable can be made constant
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.
A trailing element of an array is elided
Assignment to a variable inside a conditional statement
Assignment to an implicitly declared global variable
Assignment to constant
Cannot resolve symbol
Closure on a variable modified in loop of outer scope
Comma is expected in object literal
Comma is not valid here
Comparison of 'typeof' expression with incorrect value
Condition is always constant
Constructor call is not used or possibly used for side-effects
Declaration hides another declaration from an outer scope
Duplicate property declaration
Duplicate switch label
ECMAScript 2015 feature usage when in ES 5 or lower
ECMAScript 2016 feature usage when in ES 2015 or lower
Error in XML doc comment reference
Experimental feature usage when language level set to stable
Expression is always constant
Expression is expected after 'throw' statement
Extending prototype of native object
Heuristically unreachable code
Illegal syntax in XML code comment
'import' keyword is not allowed here.
Inconsistent function returns
Invalid JSON syntax
Invocation of non-function expression
Invoked expression is not a function value
JSON validation failed
Lexical declaration can only be declared inside a block.
Local function is redefined later
L-value expected error
Misuse of 'this' qualifier in inner function
Multiple declarations in 'for in' error
Non-parenthesized object destructuring assignment cannot be used in an expression statement
Not all code paths return a value
Object property declaration is expected
Overwriting prototype of native object
Parameter name 'arguments' clashes with pre-defined JS function-scope variable
Parameter value is not used
Path for reference comment not found
Possible mistake: ambiguous lambda block and object literal
Property getter cannot have parameters
Property setter must have a single parameter
Qualifier can be 'null' or 'undefined'
Qualifier is 'null' or 'undefined'
Redeclaration of let/const
Return statement with a value in the global scope
Similar expressions comparison
Statement is possibly incorrectly broken by a newline
'super' must be called before accessing 'this' in the constructor of a derived class.
Suspicious expression statement
There is no .hasOwnProperty() check in a body of 'for in' loop. This will cause an enumeration of prototype properties
Trailing redundant comma in object properties list may be error
Triple-slash directives are only valid at the top of the file
Usage of possibly unassigned local variable
Usage of unassigned local variable
Use 'break' or 'continue' outside of loop body
Use of expression after break or continue
Use of implicitly declared global variable
Use of possibly unassigned property or global variable
Use of 'this' in global context
Using of 'arguments.caller' and 'arguments.callee'
Using of coerced equality (using of coerced equality operator with 'null' or 'undefined')
Variable is used before it is declared
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.
Assigned value is never used
Redundant empty finally block
Redundancies in Symbol Declarations (11 inspections)
This category includes code inspections, mostly with the warning severity level, which detect empty and unused symbol declarations.
Assignment of a local variable to itself is redundant
Duplicate local declaration
Redundant 'else' block
Redundant local class name
Redundant local function name
Unused local variable / function / class
Unused parameter of inherited member
Unused property or function
Spelling issues (3 inspections)
These inspections detect typos in various contexts.
Strict mode violations (9 inspections)
Calling 'delete' on non-qualified identifier in 'strict mode'
Duplicate parameter declaration in 'strict mode'
Duplicate property declaration in 'strict mode'
Octal literals and escape sequences using in 'strict mode'
Using of 'arguments.caller' and 'arguments.callee' in 'strict mode'
Using of 'eval'/'arguments' name in 'strict mode'
Using of future reserved keywords in 'strict mode'
Using of undeclared global variable
Using of 'with' statements in 'strict mode'
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 page of ReSharper options (Alt+R, O). You can also fix issues that these inspection detect using code cleanup.
Function is used before it is declared
Function is used outside of scope which it is declared
Non-compliant quotes around string literal
Variable is used in inner scope before it is declared
Variable is used outside of scope which it is declared