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Prevent Dual File Uploading

This article shows step by step how to prevent dual uploading of a file which has already been uploaded.

Prevent Dual Files Uploading

  1. Add new RadCloudUpload control.

  2. Handle OnClientFileUploading

<telerik:RadCloudUpload ID="RadCloudUpload1" runat="server" ProviderType="Azure" OnClientFileUploading="onClientFileUploading" MultipleFileSelection="Automatic">
//Prevent uploading of file, which has already been uploaded.
function onClientFileUploading(sender, args) {
    var fileName = args.get_fileName();
    var uploadedFiles = sender.get_uploadedFiles();
    for (var i = 0; i < uploadedFiles.length; i++) {
        if (uploadedFiles[i].originalFileName === fileName) {
            alert(fileName + ' has already been uploaded.');

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