[Boolean] is a primitive built-in data type used to represent the value true or false. Literal true and false are produced with  the words 'true' or 'false' (no quotes, not case-sensitive).

Calling the boolean() method with no parameters will return false. Calling the method with any other single parameter will return either true or false depending on the following:

The following values are considered to be false:

• The empty string ''
• The integer zero 0 or decimal zero 0.0
• [null] or [void]
• Boolean false

Every other value is considered true.

A value is implicitly converted to true or false when used as the single operand to the 'if' or 'while' constructs.