Learning ActionScript 3.0

Chapter 3. PROPERTIES, METHODS, AND EVENTS

In addition to the core language fundamentals reviewed in the previous chapter, you will find that the majority of your scripts are written using properties, methods, and events. These are the basic building blocks of most scripted tasks and allow you to get and set characteristics of, issue instructions to, and react to input from, many Flash elements.

• Properties. Properties are somewhat akin to adjectives in that they describe the object being modified or queried. For example, you can check or set the width of a button. Most properties are read-write, in that you can both get and set their values. Some properties, however, are read-only, which means you can ask for, but not change, their values.

• Methods. Methods are a bit like verbs. They tell objects to do something, such as play and stop. In some cases, methods can be used to simplify the setting of properties. You might use a method called setSize(), for example, to simultaneously set the width and height of something. Other methods are more unique, such as navigateToURL(), which instructs a browser to display a web page.

• Events. Events are the catalysts that trigger the actions you write, setting properties and calling methods. For instance, a user might click the mouse button, which would then result in a mouse event. That event then causes a function to execute, performing the desired actions. Event handlers are the ActionScript middlemen that trap the events and actually call the ...