function dataURLtoFile(dataurl, filename) {
      var arr = dataurl.split(','),
          mime = arr[0].match(/:(.*?);/)[1],
          bstr = atob(arr[1]),
          n = bstr.length,
          u8arr = new Uint8Array(n);

      while (n--) {
          u8arr[n] = bstr.charCodeAt(n);
      }

      return new File([u8arr], filename, { type: mime });
  }