Control file downloads in PDF Viewer

13 Feb 20261 minute to read

Use the downloadStart event to intercept the start of a viewer download and optionally cancel it. Set args.cancel = true in the event handler to prevent the download.

  • Include the JavaScript PDF Viewer script and the Download/Toolbar modules if the download feature is used.
  • Ensure the viewer instance is initialized before assigning the downloadStart handler.
pdfviewer.downloadStart = args => {
   // Apply custom logic here
   args.cancel = true; // Prevent the download action
};

By default, args.cancel is false, so the download proceeds unless explicitly canceled.

Flexibility

Leverage the downloadStart event to apply custom rules for allowing or preventing downloads based on application logic.