字节转换为多少mb,kb

function fileSize(size) {      var string;      if (size >= 1024 * 1024 * 1024 * 1024 / 10) {        size = size / (1024 * 1024 * 1024 * 1024 / 10);        string = "TB";      } else if (size >= 1024 * 1024 * 1024 / 10) {        size = size / (1024 * 1024 * 1024 / 10);        string = "GB";      } else if (size >= 1024 * 1024 / 10) {        size = size / (1024 * 1024 / 10);        string = "MB";      } else if (size >= 1024 / 10) {        size = size / (1024 / 10);        string = "KB";      } else {        size = size * 10;        string = "b";      }      return (Math.round(size) / 10) + string; };