JS base64转blob 格式

export const toBlob = (base64, fileType) => {
  const bytes = window.atob(base64);
  let n = bytes.length;
  const u8arr = new Uint8Array(n);
  while (n--) {
    u8arr[n] = bytes.charCodeAt(n);
  }
  return new Blob([u8arr], {type: fileType});
};