lunar-calendar-plus/src/core/lunarDay.js

lunar-calendar-plus是一个可自定义设置假期、节日;获取指定农历日期、节气、每日宜忌、天文历等灵活的js库。支持Typescript！

/*
 * @Description:
 * @version:
 * @Author: XJ
 * @Date: 2021-01-12 09:24:12
 */
"use strict";

/**
 * 返回至今天数
 * @param {*} y
 * @param {*} m
 * @param {*} d
 */
function distance(y, m, d) {
  return (Date.UTC(y, m, d) - Date.UTC(1900, 0, 31)) / 86400000;
}

function lunarDay(yearHandle) {
  // Year Handler
  this.yearHandle = yearHandle;
  // Year Data Cache
  this.yearCache = {};
  // Year Data Offset
  this.offset = 0;
}

/**
 * 指定年月日的天数
 * @param {*} dateObj
 */
lunarDay.prototype.calDay = function (dateObj) {
  this.offset = distance(
    dateObj.getFullYear(),
    dateObj.getMonth(),
    dateObj.getDate()
  );

  // 当前农历所在的年份
  return this.calMonth(this.calYear());
};

/**
 * 获取阴历月份
 */
lunarDay.prototype.calMonth = function (currLeapYear) {
  var isLeap = false;
  var tempData = 0;

  // 存在跨年的情况,缓存里是不存在第二年的
  if (!this.yearCache[currLeapYear])
    this.yearCache[currLeapYear] = this.yearHandle.getLeapMonth(currLeapYear);

  /**
   * 阴历年份内所有月的天数
   */
  for (var currMaxMon = 1; currMaxMon < 13 && this.offset > 0; currMaxMon++) {
    // 如果存在闰月,则先加原本月份的天数再加上闰月的天数
    if (
      this.yearCache[currLeapYear].isLeap &&
      !isLeap &&
      currMaxMon == this.yearCache[currLeapYear].leapMonth + 1
    ) {
      currMaxMon--;
      tempData = this.yearCache[currLeapYear].day;
      isLeap = true;
    } else {
      tempData = this.yearHandle.getMonthDay(currLeapYear, currMaxMon);
    }
    this.offset -= tempData;
  }

  /**
   * 当前阴历所在的月份
   */
  if (this.offset < 0) {
    --currMaxMon;
    this.offset += tempData;
  } else if (
    this.offset == 0 &&
    currMaxMon == this.yearCache[currLeapYear].leapMonth + 1
  ) {
    // 不在并闰月且有闰月则减去一个月
    --currMaxMon;
  }

  return { year: currLeapYear, month: currMaxMon, day: this.offset + 1 };
};

/**
 * 获取当前阴历年
 * @param {*} y
 */
lunarDay.prototype.calYear = function () {
  var tempData = 0;
  for (var i = 1900; i < 2100 && this.offset > 0; i++) {
    if (this.yearCache[i]) {
      tempData = this.yearCache[i].allYearDay;
    } else {
      var allDay = this.yearHandle.yearDay(i);
      var leapYear = this.yearHandle.getLeapMonth(i);
      // Add Cache
      leapYear["allYearDay"] = leapYear["isLeap"]
        ? (allDay += leapYear["day"])
        : allDay;
      this.yearCache[i] = leapYear;

      tempData = leapYear["allYearDay"];
    }

    this.offset -= tempData;
  }

  // 前一年农历已经过去的天数
  if (this.offset < 0) {
    this.offset += tempData;
    --i;
  }
  return i;
};

module.exports = lunarDay;