goTorrent/goTorrentWebUI/node_modules/react-dropzone/examples/File Dialog/Readme.md

You can programmatically invoke default OS file prompt. In order to do that you'll have to set the ref on your Dropzone instance and call the instance open method.

let dropzoneRef;

<div>
  <Dropzone ref={(node) => { dropzoneRef = node; }} onDrop={(accepted, rejected) => { alert(accepted) }}>
      <p>Drop files here.</p>
  </Dropzone>
  <button type="button" onClick={() => { dropzoneRef.open() }}>
      Open File Dialog
  </button>
</div>

The completion handler for the open function is also the onDrop function.