ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Working with arrays
var poets:Array = ["Blake", "cummings", "Angelou", "Dante"];
poets.sort(); // default sort
trace(poets); // output: Angelou,Blake,Dante,cummings
poets.sort(Array.CASEINSENSITIVE);
trace(poets); // output: Angelou,Blake,cummings,Dante
poets.sort(Array.DESCENDING);
trace(poets); // output: cummings,Dante,Blake,Angelou
poets.sort(Array.DESCENDING | Array.CASEINSENSITIVE); // use two options
trace(poets); // output: Dante,cummings,Blake,Angelou
Custom sorting with the sort() method (Array and Vector classes)
In addition to the basic sorting that’s available for an Array object, you can also define a custom sorting rule. This
technique is the only form of the sort() method that is available for the Vector class. To define a custom sort, you
write a custom sort function and pass it as an argument to the sort() method.
For example, if you have a list of names in which each list element contains a person’s full name, but you want to sort
the list by last name, you must use a custom sort function to parse each element and use the last name in the sort
function. The following code shows how this can be done with a custom function that is used as a parameter to the
Array.sort() method:
var names:Array = new Array("John Q. Smith", "Jane Doe", "Mike Jones");
function orderLastName(a, b):int
{
var lastName:RegExp = /\b\S+$/;
var name1 = a.match(lastName);
var name2 = b.match(lastName);
if (name1 < name2)
{
return -1;
}
else if (name1 > name2)
{
return 1;
}
else
{
return 0;
}
}
trace(names); // output: John Q. Smith,Jane Doe,Mike Jones
names.sort(orderLastName);
trace(names); // output: Jane Doe,Mike Jones,John Q. Smith
The custom sort function orderLastName() uses a regular expression to extract the last name from each element to
use for the comparison operation. The function identifier orderLastName is used as the sole parameter when calling
the sort() method on the names array. The sort function accepts two parameters, a and b, because it works on two
array elements at a time. The sort function’s return value indicates how the elements should be sorted:
A return value of -1 indicates that the first parameter, a, precedes the second parameter, b.
A return value of 1 indicates that the second parameter, b, precedes the first, a.
A return value of 0 indicates that the elements have equal sorting precedence.
Last updated 6/6/2012
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