Working with Movie Clips and Buttons > Using event methods > Defining event handler methods in the prototype object

Defining event handler methods in the prototype object

You can create a new ActionScript class for movie clips and define the event handler methods in the prototype object of that new class. Defining the methods in the prototype object makes all the instances of this symbol respond the same way to these events.

You can also add an onClipEvent or on event handler action to an individual instance to provide unique instructions that run only when that instance's event occurs. The onClipEvent and on actions don't override the event handler method; both events cause their scripts to run. However, if you define the event handler methods in the prototype object and also define an event handler method for a specific instance, the instance definition overrides the prototype definition.

 
To define an event handler method in an object's prototype object:

1	Place a movie clip symbol with linkage ID theID in library.
2	Select a frame in the Timeline of the object.
3	Choose Window > Actions to open the Actions panel if it isn't already open.
4	If the Actions panel is in normal mode, choose Expert Mode from the View Options pop-up menu above the Script pane.
5	Use the function action to define a new class in the Script pane, as in the following:
	// define a class function myClipClass() {}
	This new class will be assigned to all instances of the movie clip that are added to the movie by the Timeline, or that are added to the movie with the attachMovie or duplicateMovieClip method. If you want these movie clips to have access to the methods and properties of the built-in MovieClip object, you'll need to make the new class inherit from the MovieClip class.
6	Enter code like the following in the Script pane:
	// inherit from MovieClip class myClipClass.prototype = new MovieClip();
	Now the class myClipClass inherits all the properties and methods of the MovieClip class.
7	Enter code like the following to define the event handler methods for the new class:
	// define event handler methods for myClipClass class myClipClass.prototype.onLoad = function() {trace ("movie clip loaded");} myClipClass.prototype.onEnterFrame = function() {trace ("movie clip entered frame");}
8	Choose Window > Library to open the Library panel if it isn't already open.
9	Select the symbols that you want to associate with your new class, and choose Linkage from the pop-up menu in the upper right of the Library panel.
10	In the Linkage Properties dialog box, select Export for ActionScript.
11	Enter an identifier in the Identifier box.
	The identifier must be the same for all symbols that you want to associate with the new class. In the myClipClass example, the identifier is theID.
12	Enter code like the following in the Script pane:
	// register class Object.registerClass("theID", myClipClass); _root.attachMovie("theID","myName",1);

This registers the symbol whose linkage identifier is theID with the class myClipClass. All instances of myClipClass have event handler methods that behave as you defined them in step 6. They also behave like all instances of the class MovieClip, because you told the new class to inherit from the class MovieClip in step 5.

function myClipClass(){}

myClipClass.prototype = new MovieClip();
myClipClass.prototype.onLoad = function(){
	trace("movie clip loaded");
}
myClipClass.prototype.onPress = function(){
	trace("pressed");
}

myClipClass.prototype.onEnterFrame = function(){
	trace("movie clip entered frame");
}

myClipClass.prototype.myfunction = function(){
	trace("myfunction called");
}

Object.registerClass("myclipID",myClipClass);
_root.attachMovie("myclipID","ablue2",3);