Question

/**
 *  @param { base64 } base64
 *  @param { string } filename 转换后的文件名
 */
export const base64ToFile = (base64, filename )=> {
  let arr = base64.split(',');
  let mime = arr[0].match(/:(.*?);/)[1];
  let suffix = mime.split('/')[1] ;// 图片后缀
  let bstr = atob(arr[1]);
  let n = bstr.length;
  let u8arr = new Uint8Array(n);
  while (n--) {
    u8arr[n] = bstr.charCodeAt(n)
  }
  return new File([u8arr], `${filename}.${suffix}`, { type: mime })
};