OnClientFilesSelected
The OnClientFilesSelected client-side event occurs when files(s) are selected. This event can be cancelled, which will erase the selectedfiles collection.
The event handler receives two parameters:
The instance of the RadAsyncUpload control firing the event.
An eventArgs parameter containing the following methods:
get_count returns the count of the selected files.
set_cancel lets you cancel the event and prevent items from being uploaded
<telerik:RadAsyncUpload RenderMode="Lightweight" runat="server" ID="RadAsyncUpload1" OnClientFilesSelected="OnClientFilesSelected" MultipleFileSelection="Automatic"></telerik:RadAsyncUpload>
function OnClientFilesSelected(sender, args) {
var selectedFilesCount = args.get_count();
alert(selectedFilesCount);
}