Boolean()
129
Boolean()
Availability
Flash Player 5; behavior changed in Flash Player 7.
Usage
Boolean(
expression
)
: Boolean
Parameters
expression
An expression to convert to a Boolean value.
Returns
A Boolean value.
Description
Function; converts the parameter
expression
to a Boolean value and returns a value as described
in the following list:
•
If
expression
is a Boolean value, the return value is
expression
.
•
If
expression
is a number, the return value is
true
if the number is not zero; otherwise the
return value is
false
.
If
expression
is a string, the result is
true
if the string has a length greater than zero; 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
.
Note:
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.
Example
In the following example, expressions are converted from numeric to Boolean values:
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
This example shows a significant difference between use of the
Boolean()
function and the
Boolean class. The
Boolean()
function creates a Boolean value, and the Boolean class creates a
Boolean object. Boolean values are compared by value, and Boolean objects are compared by
reference.
CHAPTER 5
ActionScript Core Language Elements
Summary of Contents for FLEX
Page 1: ...Flex ActionScript Language Reference ...
Page 8: ......
Page 66: ...66 Chapter 2 Creating Custom Classes with ActionScript 2 0 ...
Page 76: ......
Page 133: ...break 133 See also for for in do while while switch case continue throw try catch finally ...
Page 135: ...case 135 See also break default strict equality switch ...
Page 146: ...146 Chapter 5 ActionScript Core Language Elements See also break continue while ...
Page 808: ...808 Chapter 7 ActionScript for Flash ...
Page 810: ...810 Appendix A Deprecated Flash 4 operators ...
Page 815: ...Other keys 815 Num Lock 144 186 187 _ 189 191 192 219 220 221 222 Key Key code ...
Page 816: ...816 Appendix B Keyboard Keys and Key Code Values ...
Page 822: ...822 Index ...