智能转换文件大小单位B,KB,MB,GB

public static string GetString(long b)
{
	const int GB = 1024 * 1024 * 1024;
	const int MB = 1024 * 1024;
	const int KB = 1024;
	if (b / GB >= 1)
	{
		return Math.Round(b / (float)GB, 2) + "GB";
	}
	if (b / MB >= 1)
	{
		return Math.Round(b / (float)MB, 2) + "MB";
	}
	if (b / KB >= 1)
	{
		return Math.Round(b / (float)KB, 2) + "KB";
	}
	return b + "B";
}

function ConvertSizeStr(size) {
  const GB = 1024 * 1024 * 1024
  const MB = 1024 * 1024
  const KB = 1024
  if (size / GB >= 1) {
    return Math.round((size * 100.0) / GB, 2) / 100 + 'GB'
  }
  if (size / MB >= 1) {
    return Math.round((size * 100.0) / MB, 2) / 100 + 'MB'
  }
  if (size / KB >= 1) {
    return Math.round((size * 100.0) / KB, 2) / 100 + 'KB'
  }
  return size + 'B'
}