MACROMEDIA FLEX-FLEX ACTIONSCRIPT LANGUAGE Reference page 30

var myWebSite = "http://www.macromedia.com";
getURL(myWebSite); // browser displays www.macromedia.com
You can change the value of a variable in a script as many times as you want.
The type of data that a variable contains affects how and when the variable's value changes.
Primitive data types, such as strings and numbers, are "passed by value"; this means that the
current value of the variable is used, rather than a reference to that value.
In the following example,
in line 3, the value of
of that it received in line 2.
x
var x:Number = 15;
var y:Number = x;
var x:Number = 30;
trace(x); // 30
trace(y); // 15
In the following example, the variable
passed to the
sqr()
function sqr(x:Number):Number {
var x:Number = x * x;
return x;
}
var inValue:Number = 3;
var out:Number = sqr(inValue);
trace(inValue); //3
trace(out);
The value of the variable
changes.
The object data type can contain such a large amount of complex information that a variable with
this type doesn't hold an actual value; it holds a reference to a value. This reference is similar to an
alias that points to the contents of the variable. When the variable needs to know its value,
the reference asks for the contents and returns the answer without transferring the value to
the variable.
The following example shows passing by reference:
var myArray:Array = ["tom", "josie"];
var newArray:Array = myArray;
myArray[1] = "jack";
trace(newArray); // tom,jack
This code creates an Array object called
created and is passed a reference to
" ", it affects every variable with a reference to it. The
jack
the log file. Flash uses a zero-based index, which means that 0 is the first item in the array, 1 is the
second, and so on.
30 Chapter 1: ActionScript Basics
is set to 15 and that value is copied into
x
remains 15, because
y
inValue
function and the returned value is 9:
//9
does not change, even though the value of
inValue
myArray
myArray
doesn't look to for its value; it contains the value
y x
contains a primitive value, 3, so that value is
that has two elements. The variable
. When the second element of
trace()
. When is changed to 30
y x
in the function
x
newArray
is changed to
myArray
statement sends
tom,jack
is
to