User Guide

48 ActionScript language elements
If expression is a string, the return value is as follows:
■ In files published for Flash Player 6 and earlier, the string is first converted to a number.
The value is
true if the number is not 0, otherwise the return value is false.
■ In files published for Flash Player 7 and later, the result is true if the string has a length
greater than 0; the value is
false for an empty string.
If
expression is a string, the result is true if the string has a length greater than 0; the value
is
false for an empty string.
■ If expression is undefined or NaN (not a number), the return value is false.
■ If expression is a movie clip or an object, the return value is true.
Unlike the Boolean class constructor, the
Boolean() function does not use the keyword new.
Moreover, the Boolean class constructor initializes a Boolean object to
false if no parameter
is specified, while the
Boolean() function returns undefined if no parameter is specified.
Availability: ActionScript 1.0; Flash Player 5 - Behavior changed in Flash Player 7.
Parameters
expression:Object - An expression to convert to a Boolean value.
Returns
Boolean - A Boolean value.
Example
trace(Boolean(-1)); // output: true
trace(Boolean(0)); // output: false
trace(Boolean(1)); // output: true
trace(Boolean(true)); // output: true
trace(Boolean(false)); // output: false
trace(Boolean("true")); // output: true
trace(Boolean("false")); // output: true
trace(Boolean("Craiggers")); // output: true
trace(Boolean("")); // output: false
If files are published for Flash Player 6 and earlier, the results differ for three of the preceding
examples:
trace(Boolean("true")); // output: false
trace(Boolean("false")); // output: false
trace(Boolean("Craiggers")); // output: false