The boolean function evaluates an expression and returns true or false.

Syntax

boolean( expression )

Arguments

expression
The expression to be evaluated. The expression can refer to numbers and node-sets as well as booleans.

Returns

Boolean true or false after evaluating expression.

Notes

  • 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.

Defined

XPath 1.0 4.3

Gecko support

Supported.

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 Last updated by: Sheppy,