withEffect.ts

// Track a completed download and use an effect to update the status
// of the associated upload via the latest component state.
const [finishedDownload, setFinishedDownload] = useState(null as string | null)
useEffect(() => {
  if (!finishedDownload) { return }
  const updatedPreview = localPreviews[finishedDownload]
  if (localPreviews[finishedDownload].status !== FileUploadStatus.Available) {
    const normalizedPreviews = mergePreviewsToState([{ ...updatedPreview, status: FileUploadStatus.Available }], localPreviews)
    setLocalPreviews(normalizedPreviews)
    const save = async () => {
      await savePreviews(normalizedPreviews)
    }
    save()
  }
}, [finishedDownload, localPreviews, setLocalPreviews])

const handleCompletedUploaded: HandleFileUploadFn = preview => {
  setFinishedDownload(preview.id)
}