Javascript来获取前一个工作日。返回未定义的

function getPreviousWorkday() {
  var today = new Date();
  var previousDay = new Date();

  // 获取前一天的日期
  previousDay.setDate(today.getDate() - 1);

  // 判断前一天是否为周末，如果是则继续往前推一天，直到找到工作日
  while (previousDay.getDay() === 0 || previousDay.getDay() === 6) {
    previousDay.setDate(previousDay.getDate() - 1);
  }

  return previousDay;
}

var previousWorkday = getPreviousWorkday();
console.log(previousWorkday);