Boolean expressions are expressions which, when executed, result in either "true" or "false". Boolean expressions must use at least one boolean operator (as listed above), or a Function which returns a boolean value. Boolean expressions can also use other operators and Functions.

5 < 60; // evaluates to "false"
42 != 42; // evaluates to "false"
42 == 42; // evaluates to "true"
0.isPositive; // evaluates to "true"
isNegative( -256 ); // evaluates to "true"