void
227
void
Availability
Flash Player 5.
Usage
void (
expression
)
function
functionName
():Void {}
Description
Usage 1: Operator; a unary operator that discards the
expression
value and returns an undefined
value. The
void
operator is often used in comparisons using the equality (
==
) operator to test for
undefined values.
Usage 2: Data type; used in function definitions to indicate that a function will not return a value.
Example
Usage 1: In the following ActionScript, the
void
operator is used to test for undefined values:
if (someUndefinedVariable == void (0)) {
trace("someUndefinedVariable is undefined");
}
The previous code can also be written in the following way:
if (someUndefinedVariable == undefined) {
trace("someUndefinedVariable is undefined");
}
Usage 2: In the following example, a function that returns a value is defined using the
Void
return
type, which results in a compile-time error:
function myFunction():Void {
return "This will cause a compile-time error.";
}
/* the following function call will generate a compile-time error:
**Error** Scene=Scene 1, layer=Layer 1, frame=1:Line 2: A function with return
type Void may not return a value.
return "This will cause a compile-time error.";
*/
myFunction();
CHAPTER 5
ActionScript Core Language Elements
Summary of Contents for FLEX-FLEX ACTIONSCRIPT LANGUAGE
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...