Sys.WebForms.BeginRequestEventArgs request Property
Gets the request object that represents the current postback.
To get or set property values for client API properties, you must call property accessor methods that are named with the get_ and set_ prefixes. For example, to get or set a value for a property such as cancel, you call the get_cancel or set_cancel methods.
var request = arg.get_request();
An instance of the Sys.Net.WebRequest class.