File文件流与base64图片格式转换

// base64转文件
export function base64ToFile(base64: any, fileName: string) {
  if(!base64) return
  let data = base64.split(',');
  let type = data[0].match(/:(.*?);/)[1];
  const bstr = window.atob(data[1]);
  let n = bstr.length;
  const u8arr = new Uint8Array(n);
  while (n--) {
    u8arr[n] = bstr.charCodeAt(n);
  }
  const file = new File([u8arr], `${fileName}`, {
    type: type,
  });

  return file;
}

/** 文件转base64 */
export function fileToBase64(file: File) {
  return new Promise((resolve, reject) => {
    try {
      var reader = new FileReader();
      reader.onloadend = function() {
        resolve(reader.result);
      };
      reader.readAsDataURL(file);
    } catch {
      reject();
    }
  });
}