如何使用`switch`获取上个月的名称？

// 获取当前日期
var currentDate = new Date();

// 获取当前月份
var currentMonth = currentDate.getMonth() + 1;

// 定义变量存储上个月的名称
var previousMonthName;

// 使用switch语句获取上个月的名称
switch (currentMonth) {
  case 1:
    previousMonthName = "十二月";
    break;
  case 2:
    previousMonthName = "一月";
    break;
  case 3:
    previousMonthName = "二月";
    break;
  case 4:
    previousMonthName = "三月";
    break;
  case 5:
    previousMonthName = "四月";
    break;
  case 6:
    previousMonthName = "五月";
    break;
  case 7:
    previousMonthName = "六月";
    break;
  case 8:
    previousMonthName = "七月";
    break;
  case 9:
    previousMonthName = "八月";
    break;
  case 10:
    previousMonthName = "九月";
    break;
  case 11:
    previousMonthName = "十月";
    break;
  case 12:
    previousMonthName = "十一月";
    break;
  default:
    previousMonthName = "无效月份";
}

console.log("上个月的名称是：" + previousMonthName);