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Chapter 2: ActionScript Language Reference
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 return value is as follows:
•
In files published for Flash Player 6 or earlier, the string is first converted to a number; the
value is
true
if the number is not zero,
false
otherwise.
•
In files published for Flash Player 7 or later, 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
CHAPTER 2
ActionScript Language Reference
Summary of Contents for FLASH MX
Page 1: ...ActionScript Language Reference ...
Page 20: ...20 Contents ...
Page 24: ...24 Chapter 1 Introduction ...
Page 145: ...Button onKeyDown 145 See also Button onKeyUp ...
Page 202: ...202 Chapter 2 ActionScript Language Reference See also break default strict equality switch ...
Page 282: ...282 Chapter 2 ActionScript Language Reference See also break continue while ...
Page 383: ...LoadVars addRequestHeader 383 See also XML addRequestHeader ...
Page 388: ...388 Chapter 2 my_lv load place a valid URL pointing to a text file here ...
Page 463: ...Microphone setRate 463 See also Microphone rate ...
Page 469: ...Microphone silenceLevel 469 See also Microphone gain Microphone setSilenceLevel ...
Page 480: ...480 Chapter 2 ActionScript Language Reference See also Mouse addListener ...
Page 529: ...MovieClip globalToLocal 529 See also MovieClip getBounds MovieClip localToGlobal ...
Page 612: ...612 Chapter 2 ActionScript Language Reference See also MovieClipLoader onLoadStart ...
Page 623: ...NetConnection class 623 See also NetStream class Video attachVideo ...
Page 649: ...Number 649 See also NaN Number class ...
Page 679: ...on 679 on release trace X this _x trace Y this _y stopDrag See also onClipEvent ...
Page 683: ...onUpdate 683 buttonLabel textColor my_mc labelColor ...
Page 788: ...788 Chapter 2 ActionScript Language Reference See also private public ...
Page 1001: ...Video height 1001 my_mc _height my_mc my_video height See also MovieClip _height Video width ...
Page 1022: ...1022 Chapter 2 ActionScript Language Reference See also XML createElement ...
Page 1057: ...XML xmlDecl 1057 See also XML docTypeDecl XML toString ...
Page 1070: ...1070 Chapter 2 ActionScript Language Reference ...
Page 1104: ...1104 Appendix Deprecated Language Elements ...