The required functionality cannot be implemented only with client-side code. Also, such an implementation is actually not related to the RadAsyncUpload control.
I assume you need some sort of validation, however, you should note that the file's content is not accessible on the client, but on the server only. Therefore, once the file is uploaded, you can use RadPdfProcessing
for PDF files and RadWordsProcessing
for Word files to process the files and validate them programmatically.
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