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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
Содержание FLASH MX
Страница 1: ...ActionScript Language Reference ...
Страница 20: ...20 Contents ...
Страница 24: ...24 Chapter 1 Introduction ...
Страница 39: ... logical AND 39 See also logical NOT inequality strict inequality logical OR equality strict equality ...
Страница 145: ...Button onKeyDown 145 See also Button onKeyUp ...
Страница 186: ...186 Chapter 2 ActionScript Language Reference See also Camera onActivity Camera setMotionLevel ...
Страница 202: ...202 Chapter 2 ActionScript Language Reference See also break default strict equality switch ...
Страница 282: ...282 Chapter 2 ActionScript Language Reference See also break continue while ...
Страница 329: ...import 329 For more information on importing see Importing classes and Using packages in Using ActionScript in Flash ...
Страница 383: ...LoadVars addRequestHeader 383 See also XML addRequestHeader ...
Страница 388: ...388 Chapter 2 my_lv load place a valid URL pointing to a text file here ...
Страница 402: ...402 Chapter 2 ActionScript Language Reference See also LocalConnection connect LocalConnection send ...
Страница 463: ...Microphone setRate 463 See also Microphone rate ...
Страница 469: ...Microphone silenceLevel 469 See also Microphone gain Microphone setSilenceLevel ...
Страница 471: ...Microphone silenceTimeOut 471 silenceLevel_pb label Activity level inactive See also Microphone setSilenceLevel ...
Страница 480: ...480 Chapter 2 ActionScript Language Reference See also Mouse addListener ...
Страница 518: ...518 Chapter 2 ActionScript Language Reference See also MovieClip globalToLocal MovieClip localToGlobal ...
Страница 529: ...MovieClip globalToLocal 529 See also MovieClip getBounds MovieClip localToGlobal ...
Страница 535: ...MovieClip hitTest 535 See also MovieClip getBounds MovieClip globalToLocal MovieClip localToGlobal ...
Страница 612: ...612 Chapter 2 ActionScript Language Reference See also MovieClipLoader onLoadStart ...
Страница 623: ...NetConnection class 623 See also NetStream class Video attachVideo ...
Страница 639: ...NetStream play 639 See also MovieClip attachAudio NetStream close NetStream pause Video attachVideo ...
Страница 649: ...Number 649 See also NaN Number class ...
Страница 679: ...on 679 on release trace X this _x trace Y this _y stopDrag See also onClipEvent ...
Страница 683: ...onUpdate 683 buttonLabel textColor my_mc labelColor ...
Страница 788: ...788 Chapter 2 ActionScript Language Reference See also private public ...
Страница 847: ...System security allowInsecureDomain 847 See also System security allowDomain System exactSettings ...
Страница 1001: ...Video height 1001 my_mc _height my_mc my_video height See also MovieClip _height Video width ...
Страница 1022: ...1022 Chapter 2 ActionScript Language Reference See also XML createElement ...
Страница 1057: ...XML xmlDecl 1057 See also XML docTypeDecl XML toString ...
Страница 1070: ...1070 Chapter 2 ActionScript Language Reference ...
Страница 1104: ...1104 Appendix Deprecated Language Elements ...