boolean
The boolean function evaluates an expression and returns true or false.
Syntax
js
boolean( expression )
Parameters
expression-
The expression to be evaluated. The expression can refer to numbers and node-sets as well as booleans.
Return value
Boolean true or false after evaluating expression.
Description
- A number evaluates to false if it is positive or negative zero or
NaN. Otherwise, it evaluates true. - A node-set evaluates to true if it is non-empty.
- A string evaluates to false if it an empty string. Otherwise, it evaluates to true.
- An object of a type other than the four basic types is converted to a boolean in a way that is dependent on that type.
Specifications
Gecko support
Supported.