js公历日期转为农历日期

方法：

toLunar(solarYear, solarMonth, solarDay) {
      //定义全局变量
      var CalendarData = new Array(100);
      var madd = new Array(12);
      var tgString = "甲乙丙丁戊己庚辛壬癸";
      var dzString = "子丑寅卯辰巳午未申酉戌亥";
      var numString = "一二三四五六七八九十";
      var monString = "正二三四五六七八九十冬腊";
      var weekString = "日一二三四五六";
      var sx = "鼠牛虎兔龙蛇马羊猴鸡狗猪";
      var cYear, cMonth, cDay, TheDate;
      CalendarData = new Array(
        0xa4b,
        0x5164b,
        0x6a5,
        0x6d4,
        0x415b5,
        0x2b6,
        0x957,
        0x2092f,
        0x497,
        0x60c96,
        0xd4a,
        0xea5,
        0x50da9,
        0x5ad,
        0x2b6,
        0x3126e,
        0x92e,
        0x7192d,
        0xc95,
        0xd4a,
        0x61b4a,
        0xb55,
        0x56a,
        0x4155b,
        0x25d,
        0x92d,
        0x2192b,
        0xa95,
        0x71695,
        0x6ca,
        0xb55,
        0x50ab5,
        0x4da,
        0xa5b,
        0x30a57,
        0x52b,
        0x8152a,
        0xe95,
        0x6aa,
        0x615aa,
        0xab5,
        0x4b6,
        0x414ae,
        0xa57,
        0x526,
        0x31d26,
        0xd95,
        0x70b55,
        0x56a,
        0x96d,
        0x5095d,
        0x4ad,
        0xa4d,
        0x41a4d,
        0xd25,
        0x81aa5,
        0xb54,
        0xb6a,
        0x612da,
        0x95b,
        0x49b,
        0x41497,
        0xa4b,
        0xa164b,
        0x6a5,
        0x6d4,
        0x615b4,
        0xab6,
        0x957,
        0x5092f,
        0x497,
        0x64b,
        0x30d4a,
        0xea5,
        0x80d65,
        0x5ac,
        0xab6,
        0x5126d,
        0x92e,
        0xc96,
        0x41a95,
        0xd4a,
        0xda5,
        0x20b55,
        0x56a,
        0x7155b,
        0x25d,
        0x92d,
        0x5192b,
        0xa95,
        0xb4a,
        0x416aa,
        0xad5,
        0x90ab5,
        0x4ba,
        0xa5b,
        0x60a57,
        0x52b,
        0xa93,
        0x40e95
      );
      madd[0] = 0;
      madd[1] = 31;
      madd[2] = 59;
      madd[3] = 90;
      madd[4] = 120;
      madd[5] = 151;
      madd[6] = 181;
      madd[7] = 212;
      madd[8] = 243;
      madd[9] = 273;
      madd[10] = 304;
      madd[11] = 334;

      function GetBit(m, n) {
        return (m >> n) & 1;
      }
      //农历转换
      function e2c() {
        TheDate =
          arguments.length != 3
            ? new Date()
            : new Date(arguments[0], arguments[1], arguments[2]);
        var total, m, n, k;
        var isEnd = false;
        var tmp = TheDate.getYear();
        if (tmp < 1900) {
          tmp += 1900;
        }
        total =
          (tmp - 1921) * 365 +
          Math.floor((tmp - 1921) / 4) +
          madd[TheDate.getMonth()] +
          TheDate.getDate() -
          38;
        if (TheDate.getYear() % 4 == 0 && TheDate.getMonth() > 1) {
          total++;
        }
        for (m = 0; ; m++) {
          k = CalendarData[m] < 0xfff ? 11 : 12;
          for (n = k; n >= 0; n--) {
            if (total <= 29 + GetBit(CalendarData[m], n)) {
              isEnd = true;
              break;
            }
            total = total - 29 - GetBit(CalendarData[m], n);
          }
          if (isEnd) break;
        }
        cYear = 1921 + m;
        cMonth = k - n + 1;
        cDay = total;
        if (k == 12) {
          if (cMonth == Math.floor(CalendarData[m] / 0x10000) + 1) {
            cMonth = 1 - cMonth;
          }
          if (cMonth > Math.floor(CalendarData[m] / 0x10000) + 1) {
            cMonth--;
          }
        }
      }
      function GetcDateString() {
        var tmp = "";
        if (cMonth < 1) {
          // tmp += "(闰)";
          tmp += monString.charAt(-cMonth - 1);
        } else {
          tmp += monString.charAt(cMonth - 1);
        }
        tmp += "月";
        tmp += cDay < 11 ? "初" : cDay < 20 ? "十" : cDay < 30 ? "廿" : "三十";
        if (cDay % 10 != 0 || cDay == 10) {
          tmp += numString.charAt((cDay - 1) % 10);
        }
        return tmp;
      }
      solarMonth = parseInt(solarMonth) > 0 ? solarMonth - 1 : 11;
      e2c(solarYear, solarMonth, solarDay);
      return GetcDateString();
    }

调用方式：

toLunar(2019 8, 26)；