As mentioned above, behaviors allow you to create specific functionality that can be reused and attached to specific controls and elements on your page.

Now, let us first take a glimpse at the prototype definition of Sys.Component to make us more familiar with the basic functionality of Sys.Component.

Listing 1: Prototype definition for Sys.Component

Sys.Component.prototype = {
      _id: null,
      _idSet: false,
      _initialized: false,
      _updating: false,
      get_events: Sys$Component$get_events,
      get_id: Sys$Component$get_id,
      set_id: Sys$Component$set_id,
      get_isInitialized: Sys$Component$get_isInitialized,
      get_isUpdating: Sys$Component$get_isUpdating,
      add_disposing: Sys$Component$add_disposing,
      remove_disposing: Sys$Component$remove_disposing,
      add_propertyChanged: Sys$Component$add_propertyChanged,
      remove_propertyChanged: Sys$Component$remove_propertyChanged,
      beginUpdate: Sys$Component$beginUpdate,
      dispose: Sys$Component$dispose,
      endUpdate: Sys$Component$endUpdate,
      initialize: Sys$Component$initialize,
      raisePropertyChanged: Sys$Component$raisePropertyChanged,
      updated: Sys$Component$updated
}
Sys.Component.registerClass('Sys.Component', null, Sys.IDisposable, 
Sys.INotifyPropertyChange, Sys.INotifyDisposing);

As is seen above, by deriving from the Component base class, your custom component automatically will inherit many supported features, including the following.

·         A cross-browser model for managing handler bindings to client object events

·         Automatic registration of the component in the client application as a disposable object that implements the Sys.IDisposable interface

·         Raising of notification events when properties are changed

·         Performing batch processing of component property settings, which is more efficient in script size and processing time than handling all logic in individual property get and set accessors

·         An override of the Sys.UI.Control.initialize method to initialize any properties and event listeners

MS AJAX has many built-in components, such as Application, Timer, Validator, etc. which greatly enhanced the client-side function. In the next section, however, we are going to create our own MS AJAX client-side custom components.