SPC018901: No assignment in conditional statement
SPC018902: Consider to not use, or shim the console object
SPC018904: Consider to disallow Controls Characters in Regular Expressions
SPC018905: Consider to disallow extra boolean casts
SPC018906: Disallow negated left operand of 'in' operator
SPC018907: Disallow Global Object Function Calls
SPC018908: Disallow usage of NaN directly
SPC018909: Ensure type checks are against valid types
SPC018910: Assignment to function name not allowed
SPC018911: Do not do toString directly on method objects
SPC018912: Disallow use of delete on variables
SPC018970: Catch identifiers should be unique
SPC018971: Ambiguous named function expression
SPC018972: Export not at module level
SPC018973: Numeric literal causes overflow or underflow exception
SPC018974: Strict operator always evaluates to true or false
SPC018975: Array literal trailing commas has cross-browser difference
SPC018976: Variable or function declaration redefines the catch error name
SPC018977: Constant declaration already declared
SPC018978: Duplicate lexical declaration; cannot redefine let or const variables
SPC018979: High-surrogate pair value not followed by low-surrogate value
SPC018980: Reserved words and should not be used as an identifier
SPC018981: Low-surrogate pair value not preceeded by high-surrogate value
SPC018982: Function declaration should not be inside a statement. Cross-browser behavior difference
SPC018983: Reserved word used as object literal property name; cross-browser issue
SPC018985: Identifier already in use
SPC018992: Octal literals are deprecated. Possible cross-browser behavior difference
SPC018993: New line not allowed
SPC018994: Imported module does not export name
SPC018997: Semicolon insertion
SPC018998: A statement block is expected
SPC018999: Suspect assigment
SPC2389100: Strict-mode does not allow duplicate argument names
SPC2389101: Strict-mode does not allow certain variable names
SPC2389102: Strict-mode does not allow certain function names
SPC2389103: Strict-mode does not allow duplicate property names
SPC2389104: Strict-mode does not allow assignment to certain variables
SPC2389105: Strict-mode does not allow ++ or -- on certain objects
SPC2389106: Strict-mode does not allow certain delete operands
SPC2389107: Strict-mode does not allow certain argument names
SPC2389108: Assignment to constant
SPC2389109: String literal is not safe for inline
SPC2389110: Strict-mode does not allow assignment to undefined variables
SPC2389111: End of file encountered before function is properly closed
SPC2389112: Expected ///#ENDIF directive
SPC2389113: Expected ///#ENDDEBUG directive
SPC2389114: Invalid numeric literal
SPC2389115: Suspect equality comparison
SPC2389116: Strict-mode does not allow certain catch error binding names
SPC2389117: Binding patterns in var statements require initializer
SPC2389118: Implicit object property name must be identifier
SPC2389119: Setter method must have a single format argument
SPC2389120: Rest parameter can only be last parameter
SPC2389121: Unable to convert to binding syntax
SPC2389122: Unable to convert from binding syntax
SPC2389123: Invalid binding syntax
SPC2389124: Methods not allowed in object literal bindings
SPC2389125: Expected for or if keyword
SPC2389126: Expected class element
SPC2389127: Duplicate class element name
SPC2389128: Class constructor must be regular method
SPC2389129: Class static method cannot be named 'prototype'
SPC2389130: Expected binding
SPC2389131: Multiple default exports
SPC2389132: Import statement must include module name
SPC2389133: Duplicate module declaration
SPC2389134: Imported module has no default export
SPC2389135: Expected 'from'
SPC2389136: Expected string literal
SPC2389137: Expected specifier set
SPC2389138: Arrow functions cannot be constructors
SPC2389139: Application Error
SPC2389140: No Source Error
SPC238950: Could not parse JavaScript code
SPC238951: Syntax error
SPC238952: Expected ':'
SPC238953: Expected ';'
SPC238954: Expected '('
SPC238955: Expected ')'
SPC238956: Expected ']'
SPC238957: Expected '{'
SPC238958: Expected '}'
SPC238959: Expected identifier
SPC238960: Expected '='
SPC238961: Illegal assignment
SPC238962: Syntax error in regular expression
SPC238963: Invalid character
SPC238964: Unterminated string constant
SPC238965: Unterminated comment
SPC238966: 'return' statement outside of function
SPC238967: Can't have 'break' outside of loop
SPC238968: Can't have 'continue' outside of loop
SPC238969: unused label
SPC238970: Expected hexadecimal digit
SPC238971: Expected 'while'
SPC238972: Label redefined
SPC238973: Label not found
SPC238974: 'default' can only appear once in a 'switch' statement
SPC238975: Expected identifier or string
SPC238976: Expected '@end'
SPC238977: Conditional compilation is turned off
SPC238978: Expected 'catch'
SPC238979: Unmatched 'else'; no 'if' defined
SPC238980: Expected ','
SPC238981: Missing 'case' or 'default' statement
SPC238982: Unmatched '@end'; no '@if' defined
SPC238983: Unmatched '@else'; no '@if' defined
SPC238984: Unmatched '@elif'; no '@if' defined
SPC238985: Expecting more source characters
SPC238987: Expected ',' or ')'
SPC238988: Expected ',' or ']'
SPC238989: Expected expression
SPC238990: Unexpected ';'
SPC238991: Too many tokens have been skipped in the process of recovering from errors. The file may not be a JScript.NET file
SPC238992: Did you intend to have an empty statement for this branch of the if statement?
SPC238993: A variable argument list must be the last argument
SPC238994: Function expression expected
SPC238995: JSParser Exception
SPC238996: Resource reference must be single constant value
SPC238997: Conditiona compilation structure too complex
SPC238998: Unterminated ASP.NET block
SPC238999: Strict-mode does not allow with-statements
Expand Minimize

SPC018905: Consider to disallow extra boolean casts

In contexts such as an if statement's test where the result of the expression will already be coerced to a Boolean, casting to a Boolean via double negation (!!) is unnecessary.

CheckId SPC018905
TypeName NoExtraBooleanCasts
Severity Warning
Type JavaScriptFile
Resolution

Bad Practice

if(!!foo) {
  return false;
}

Good Practice
if(foo) {
  return true;
}
if(!foo) {
  return false;
}

See also
Disclaimer: The views and opinions expressed in this documentation and in SPCAF do not necessarily reflect the opinions and recommendations of Microsoft or any member of Microsoft. SPCAF and RENCORE are registered trademarks of Rencore. All other trademarks, service marks, collective marks, copyrights, registered names, and marks used or cited by this documentation are the property of their respective owners.