Flash CS3 Documentation

Learning ActionScript 2.0 in Adobe Flash > Functions and Methods > About functions and methods > Targeting and calling user-defined functions

Targeting and calling user-defined functions

User-defined functions are simply functions that you create yourself to use in applications, as opposed to functions in built-in classes that perform predefined functions. You name the functions yourself and add statements in the function block. Previous sections cover writing functions such as named, unnamed, and callback functions. For information on naming functions, see Naming functions, and for information on using functions, see Using functions in Flash.

You can use a target path to call a function in any timeline from any timeline, including from a timeline of a loaded SWF file. To call a function, type the target path to the name of the function, if necessary, and pass any required parameters inside parentheses. There are several forms of syntax for user-defined functions. The following code uses a path to call the initialize() function, which was defined on the current timeline and requires no parameters:

this.initialize();

The following example uses a relative path to call the list() function, which was defined in the functionsClip movie clip:

this._parent.functionsClip.list(6);

For information on writing named functions, see Writing named functions. For more information on parameters, see Passing parameters to a function.

You can also define your own named functions. For example, the following named function helloWorld() is user defined:

function helloWorld() {
    trace("Hello world!");
};

The following example shows you how to use a user-defined function in a FLA file.

To create and call a simple user-defined function:

1. Create a new Flash document and save it as udf.fla.
2. Add the following ActionScript to Frame 1 of the main Timeline:

   function traceHello(name:String):Void {
       trace("hello, " + name + "!");
   }
   traceHello("world"); // hello, world!
   

   The previous code creates a user-defined function named traceHello() that takes one argument, name, and traces a greeting message. To call the user-defined function, you can call traceHello from the same timeline as the function definition and pass a single string value.

3. Select Control > Test Movie to test the Flash document.

For more information on named functions, see Writing named functions. Classes contain many user-defined functions. For information on writing functions in class files, see Using functions in Flash. Also see the following sections in Classes: Using methods and properties from a class file, About public, private, and static methods and properties (members), and About class members.

Flash CS3