C# 4 and .NET 4

What is ajax ❘ 1237
The PagerequestManager and application objects
Among the most useful classes that the AJAX Library provides are the PageRequestManager
and Application classes. You will find PageRequestManager in the Sys.WebForms namespace and
Application in the Sys namespace. The important thing about these classes is that they expose several
events that you can attach JavaScript event handlers to. These events occur at particularly interesting points
in the lifecycle of a page (for Application) or partial-page postback (for PageRequestManager) and enable
you to perform operations at these critical times.
The AJAX Library defines event handlers in a similar way to event handlers in the .NET Framework. Every
event handler has a similar signature, with two parameters. The first parameter is a reference to the object
that generated the event. The second parameter is an instance of the Sys.EventArgs class or an instance of
a class that derives from this class. Many of the events exposed by PageRequestManager and Application
include specialized event argument classes that you can use to determine more information about the event.
The following table lists these events in the order they will occur in a page that is loaded, triggers a partialpage
postback, and is then closed.
eVenT
Application.init
Application.load
PageRequestManager.initializeRequest
PageRequestManager.beginRequest
PageRequestManager.pageLoading
desCriPTion
This event is the first to occur in the lifecycle of a page. It
is raised after all the JavaScript files have been loaded but
before any objects in the application have been created.
This event fires after the objects in the application
have loaded and been initialized. You will often use an
event handler attached to this event to perform actions
when the page is first loaded. You can also provide an
implementation for a function called pageLoad() on a
page, which is automatically defined as an event handler
for this event. It sends event arguments by using a Sys
.ApplicationLoadEventArgs object, which includes the
isPartialLoad property that you can use to determine if
a partial-page postback has occurred. Access this property
with the get_isPartialLoad() accessor.
This event occurs before a partial-page postback, before
the request object is created. You can use the Sys
.WebForms.InitializeRequestEventArgs event
argument properties to access the element that triggered
the postback (postBackElement) and the underlying
request object (request).
This event occurs before a partial-page postback, after the
request object is created. You can use the Sys.WebForms
.BeginRequestEventArgs event argument properties
to access the element that triggered the postback
(postBackElement) and the underlying request object
(request).
This event is raised after a partial-page postback,
before any subsequent processing occurs. This processing
can include elements that will be deleted or
updated, which you can reference through the Sys
.WebForms.PageLoadingEventArgs object by using the
panelsDeleting and panelsUpdating properties.
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