logical not

Summary

Performs logical negation on an expression.

Syntax

result = ! expression

result

Any variable.

expression

Any expression.

Examples

var x = 5;
var y = 7;
var z;
z = ! (x = y); // result: z = true
z = ! (y > x); // result: z = false

Remarks

The following table illustrates how result is determined.

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.

Attributions

• Microsoft Developer Network: Article