Performs logical negation on an expression.
The following table illustrates how result is determined.
If expression is
Then result is
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, Internet Explorer 11 standards. Also supported in Store apps (Windows 8 and Windows Phone 8.1). See Version Information.