Sys.WebForms.PageLoadingEventArgs dataItems Property
Gets a JSON data structure that contains data items that were registered by using the RegisterDataItem method of the ScriptManager class.
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 obj = eventArgs.get_dataItems();
A JSON data structure that contains name/value pairs that were registered as data items by using the RegisterDataItem method of the ScriptManager class.
A page or control must be in partial-page rendering mode to register data items that use the RegisterDataItem method of the ScriptManager class. Use the IsInAsyncPostBack property to check whether the page is in partial-page rendering mode.
The dataItems property returns a JSON data structure that contains name/value pairs. The name is the unique ID of the control that is used in the control parameter of the RegisterDataItem method. The value is the dataItem parameter of the RegisterDataItem method.