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JavaScript Operators
Addition Assignment Operator (+=) (JavaScript)
Addition Operator (+) (JavaScript)
Assignment Operator (=) (JavaScript)
Bitwise AND Assignment Operator (&=) (JavaScript)
Bitwise AND Operator (&) (JavaScript)
Bitwise Left Shift Operator (<<) (JavaScript)
Bitwise NOT Operator (~) (JavaScript)
Bitwise OR Assignment Operator (|=) (JavaScript)
Bitwise OR Operator (|) (JavaScript)
Bitwise Right Shift Operator (>>) (JavaScript)
Bitwise XOR Assignment Operator (^=) (JavaScript)
Bitwise XOR Operator (^) (JavaScript)
Comma Operator (,) (JavaScript)
Comparison Operators (JavaScript)
Compound Assignment Operators (JavaScript)
Conditional (Ternary) Operator (?:) (JavaScript)
delete Operator (JavaScript)
Division Assignment Operator (/=) (JavaScript)
Division Operator (/) (JavaScript)
in Operator (JavaScript)
Increment (++) and Decrement (--) Operators (JavaScript)
instanceof Operator (JavaScript)
Left Shift Assignment Operator (<<=) (JavaScript)
Logical AND Operator (&&) (JavaScript)
Logical NOT Operator (!) (JavaScript)
Logical OR Operator (||) (JavaScript)
Modulus Assignment Operator (JavaScript)
Modulus Operator (JavaScript)
Multiplication Assignment Operator (*=) (JavaScript)
Multiplication Operator (*) (JavaScript)
new Operator (JavaScript)
Right Shift Assignment Operator (>>=) (JavaScript)
Subtraction Assignment Operator (-=) (JavaScript)
Subtraction Operator (-) (JavaScript)
typeof Operator (JavaScript)
Unsigned Right Shift Assignment Operator (>>>=) (JavaScript)
Unsigned Right Shift Operator (>>>) (JavaScript)
void Operator (JavaScript)
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Logical NOT Operator (!) (JavaScript)

JavaScript - Internet Explorer 10

Performs logical negation on an expression.

Copy 
result = !expression
result

Any variable.

expression

Any expression.

The following table illustrates how result is determined.

If expression is

Then result is

True

False

False

True

All unary operators, such as the ! operator, evaluate expressions as follows:

  • If applied to undefined or null expressions, a run-time error is raised.

  • Objects are converted to strings.

  • Strings are converted to numbers if possible. If not, a run-time error is raised.

  • Boolean values are treated as numbers (0 if false, 1 if true).

The operator is applied to the resulting number.

For the ! operator, if expression is nonzero, result is zero. If expression is zero, result is 1.

Supported in the following document modes: Quirks, Internet Explorer 6 standards, Internet Explorer 7 standards, Internet Explorer 8 standards, Internet Explorer 9 standards, Internet Explorer 10 standards. Also supported in Windows Store apps. See Version Information.

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