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RadUpload has been replaced by RadAsyncUpload, Telerik’s next-generation ASP.NET upload component. If you are considering Telerik’s Upload control for new development, check out the documentation of RadAsyncUpload or the control’s product page. If you are already using RadUpload in your projects, you may be interested in reading how easy the transition to RadAsyncUpload is and how you can benefit from it in this blog post. The official support for RadUpload has been discontinued in June 2013 (Q2’13), although it is still be available in the suite. We deeply believe that RadAsyncUpload can better serve your upload needs and we kindly ask you to transition to it to make sure you take advantage of its support and the new features we constantly add to it.

The OnClientFileSelected client-side event occurs when a file is selected in a file input control: either when the control loses focus after the user types in a value, or when the user selects a file using the browser.

The event handler receives two parameters:

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

  2. An eventArgs parameter containing the following method:

    • get_fileInputField returns the file input field for the file that was just selected.

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

    • get_rowIndex returns the index of the row

The following example clears the file input field if the selected file has an invalid extension:

<telerik:radupload id="RadUpload1" runat="server" allowedfileextensions=".zip,.txt"
    onclientfileselected="checkExtension" />
<script type="text/javascript">

    function checkExtension(radUpload, eventArgs) {
        var input = eventArgs.get_fileInputField();
        if (!radUpload.isExtensionValid(input.value)) {
            var inputs = radUpload.getFileInputs();
            for (i = 0; inputs.length > i; i++) {
                if (inputs[i] == input) {
                    alert(input.value + " does not have a valid extension.");

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