如何在JavaScript中获取客户端时区？

function getClientTimezone() {
  const dtf = new Intl.DateTimeFormat('en', { timeZoneName: 'short' });
  const referenceDate = new Date('2020-01-01T00:00:00');
  const match = dtf.format(referenceDate).match(/([A-Z]+[+-]\d+)/);
  return match ? match[0] : '';
}

console.log(getClientTimezone()); // 输出客户端时区，例如："GMT+8"