Function download

packages/res/src/download.ts:19–56

(req: Request, res: Response)

type Res = Pick<S, 'setHeader' | 'statusCode' | 'writeHead'> & NodeJS.WritableStream

export const download = <Request extends Req = Req, Response extends Res = Res>(req: Request, res: Response) => (
  path: string,
  filename?: string | Callback,
  options?: DownloadOptions | Callback,
  cb?: Callback
): Response => {
  let done = cb
  let name = filename as string
  let opts = (options || null) as DownloadOptions

  // support function as second or third arg
  if (typeof filename === 'function') {
    done = filename
    name = null
  } else if (typeof options === 'function') {
    done = options
    opts = null
  }

  // set Content-Disposition when file is sent
  const headers = {
    'Content-Disposition': contentDisposition(name || path)
  }

  // merge user-provided headers
  if (opts && opts.headers) {
    for (const key of Object.keys(opts.headers)) {
      if (key.toLowerCase() !== 'content-disposition') headers[key] = opts.headers[key]
    }
  }

  // merge user-provided options
  opts = { ...opts, headers }

  // send file

  return sendFile(req, res)(opts.root ? path : resolve(path), opts, done || (() => undefined))
}

export const attachment = <Response extends Pick<S, 'getHeader' | 'setHeader'> = Pick<S, 'getHeader' | 'setHeader'>>(
  res: Response