GPS周 北斗周 年月日转换

// 年月日转GPS周 格式为 2019-11-11
function UTC2GPS(dateTime) {
	var year;
	var month;
	var day;
	var DayofYear = 0;
	var DayofMonth = 0;

	year = parseInt(dateTime.substr(0, 4));
	month = parseInt(dateTime.substr(5, 2));
	day = parseInt(dateTime.substr(8, 2));

	// 从1980年到当前年的上一年经过的天数
	for (var i = 1980; i < year; i++) {
		if ((i % 4 == 0 && i % 100 != 0) || i % 400 == 0)
			DayofYear += 366;
		else
			DayofYear += 365;
	}

	// 从一月到当前月的上一月经历的天数
	for (var i = 1; i < month; i++) {
		if (i == 1 || i == 3 || i == 5 || i == 7 || i == 8 || i == 10 || i == 12)
			DayofMonth += 31;
		else if (i == 4 || i == 6 || i == 9 || i == 11)
			DayofMonth += 30;
		else {
			if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0)
				DayofMonth += 29;
			else
				DayofMonth += 28;
		}
	}
	var Day;
	Day = DayofMonth + day + DayofYear - 6;
	var weekNo = parseInt(Day / 7);
	return weekNo;
}

// 年月日转北斗周
function UTC2BeiDou(dateTime) {
	var weekNo = UTC2GPS(dateTime);
	var beidouWeek = weekNo - 1356;
	if (beidouWeek < 1000) {
		beidouWeek = '0' + beidouWeek;
	}
	return beidouWeek;
}

// 北斗周转年月日
function beidou2UTC(week) {
	var weekDay = (parseInt(week) + 1356) * 7;
	var weekYear = 0;
	var currentYear = new Date().getFullYear();
	var dayofYear = 0;

	for (let i = 1980; i <= currentYear; i++) {
		if ((i % 4 == 0 && i % 100 != 0) || i % 400 == 0) {
			dayofYear += 366;
			if (0 <= (dayofYear - weekDay) && (dayofYear - weekDay) <= 366) {
				weekYear = i;
				break;
			}
		} else {
			dayofYear += 365;
			if (0 <= (dayofYear - weekDay) && (dayofYear - weekDay) <= 365) {
				weekYear = i;
				break;
			}
		}
	};

	var dayofMonth = 0;
	var weekDayInYear = dayofYear - weekDay;
	var weekMonth = 0;

	for (var i = 12; i > 0; i--) {
		if (i == 1 || i == 3 || i == 5 || i == 7 || i == 8 || i == 10 || i == 12) {
			dayofMonth += 31;
			
			if (0 <= (dayofMonth - weekDayInYear) && (dayofMonth - weekDayInYear) <= 31) {
				console.log('单数', dayofMonth - weekDayInYear, i);

				weekMonth = i;
				break;
			}
		} else if (i == 4 || i == 6 || i == 9 || i == 11) {
			dayofMonth += 30;

			if (0 <= (dayofMonth - weekDayInYear) && (dayofMonth - weekDayInYear) <= 30) {
				console.log('双数', dayofMonth - weekDayInYear, i);

				weekMonth = i;
				break;
			}
		} else {
			if ((dayofYear % 4 == 0 && dayofYear % 100 != 0) || dayofYear % 400 == 0) {
				dayofMonth += 29;

				if (0 <= (dayofMonth - weekDayInYear) && (dayofMonth - weekDayInYear) <= 29) {
					console.log('闰年', dayofMonth - weekDayInYear, i);

					weekMonth = i;
					break;
				}
			} else {
				dayofMonth += 28;
				if (0 <= (dayofMonth - weekDayInYear) && (dayofMonth - weekDayInYear) <= 28) {
					console.log('非闰年', dayofMonth - weekDayInYear, i);

					weekMonth = i;
					break;
				}
			}
		};		
	};

	var weekMonthDay = dayofMonth - weekDayInYear + 6
	if (weekMonth >= 1 && weekMonth <= 9) {
    weekMonth = "0" + weekMonth;
  }
  if (weekMonthDay >= 0 && weekMonthDay <= 9) {
    weekMonthDay = "0" + weekMonthDay;
  }

	return weekYear + '-' + weekMonth + '-' + weekMonthDay;
}