No assignment in conditional statement
Consider to not use, or shim the console object
Consider to disallow Controls Characters in Regular Expressions
Consider to disallow extra boolean casts
Disallow negated left operand of 'in' operator
Disallow Global Object Function Calls
Disallow usage of NaN directly
Ensure type checks are against valid types
Assignment to function name not allowed
Do not do toString directly on method objects
Disallow use of delete on variables
Catch identifiers should be unique
Ambiguous named function expression
Export not at module level
Numeric literal causes overflow or underflow exception
Strict operator always evaluates to true or false
Array literal trailing commas has cross-browser difference
Variable or function declaration redefines the catch error name
Constant declaration already declared
Duplicate lexical declaration; cannot redefine let or const variables
High-surrogate pair value not followed by low-surrogate value
Reserved words and should not be used as an identifier
Low-surrogate pair value not preceeded by high-surrogate value
Function declaration should not be inside a statement. Cross-browser behavior difference
Reserved word used as object literal property name; cross-browser issue
Identifier already in use
Octal literals are deprecated. Possible cross-browser behavior difference
New line not allowed
Imported module does not export name
Semicolon insertion
A statement block is expected
Suspect assigment
Strict-mode does not allow certain variable names
Strict-mode does not allow certain function names
Strict-mode does not allow duplicate property names
Strict-mode does not allow assignment to certain variables
Strict-mode does not allow ++ or -- on certain objects
Strict-mode does not allow certain delete operands
Strict-mode does not allow certain argument names
Assignment to constant
String literal is not safe for inline
Strict-mode does not allow assignment to undefined variables
End of file encountered before function is properly closed
Expected ///#ENDIF directive
Expected ///#ENDDEBUG directive
Invalid numeric literal
Suspect equality comparison
Strict-mode does not allow certain catch error binding names
Binding patterns in var statements require initializer
Implicit object property name must be identifier
Setter method must have a single format argument
Rest parameter can only be last parameter
Unable to convert to binding syntax
Unable to convert from binding syntax
Invalid binding syntax
Methods not allowed in object literal bindings
Expected for or if keyword
Expected class element
Duplicate class element name
Class constructor must be regular method
Class static method cannot be named 'prototype'
Expected binding
Multiple default exports
Import statement must include module name
Duplicate module declaration
Imported module has no default export
Expected 'from'
Expected string literal
Expected specifier set
Arrow functions cannot be constructors
Application Error
No Source Error
Could not parse JavaScript code
Syntax error
Expected ':'
Expected ';' between statements
Expected '('
Expected ')'
Expected ']'
Expected '{'
Expected '}'
Expected identifier
Expected '='
Illegal assignment
Syntax error in regular expression
Invalid character
Unterminated string constant
Unterminated comment
'return' statement outside of function
Can't have 'break' outside of loop
Can't have 'continue' outside of loop
unused label
Expected hexadecimal digit
Expected 'while'
Label redefined
Label not found
'default' can only appear once in a 'switch' statement
Expected identifier or string
Expected '@end'
Conditional compilation is turned off
Expected 'catch'
Unmatched 'else'; no 'if' defined
Expected ','
Missing 'case' or 'default' statement
Unmatched '@end'; no '@if' defined
Unmatched '@else'; no '@if' defined
Unmatched '@elif'; no '@if' defined
Expecting more source characters
Expected ',' or ')'
Expected ',' or ']'
Expected expression
Unexpected ';'
Too many tokens have been skipped in the process of recovering from errors. The file may not be a JScript.NET file
Did you intend to have an empty statement for this branch of the if statement?
A variable argument list must be the last argument
Function expression expected
JSParser Exception
Resource reference must be single constant value
Conditiona compilation structure too complex
Unterminated ASP.NET block
Strict-mode does not allow with-statements
Strict-mode does not allow duplicate argument names
Expand Minimize

Ensure type checks are against valid types

This rule prevents spelling mistakes in 'typeof' unary operator checks. Valid types are symbol, undefined, object, boolean, number, string and function.

CheckId SPC018909
TypeName EnsureTypeofValid
Severity CriticalError
Type JavaScriptFile
Resolution

Bad Practice

if(typeof foo == 'strgni') {
  return false;
}

Good Practice
if(typeof foo == 'string') {
  return false;
}

See also
Message Suppression
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