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The OnClientFileUploading client-side event occurs when a file has starteduploading.

The event handler receives two parameters:

  1. The instance of the RadAsyncUpload control firing the event.

  2. An eventArgs parameter containing the following methods:

  • get_row returns the row containing the file input field for the file that was just selected (<li> element)

  • get_fileName returns the name of the file selected

  • set_cancel cancel the upload process

<telerik:RadAsyncUpload RenderMode="Lightweight" runat="server" ID="RadAsyncUpload1" OnClientFileUploading="OnClientFileUploading"></telerik:RadAsyncUpload>
function OnClientFileUploading(sender, args) {
    if (args.get_fileName().length > 20) {
    else {
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