7 examples of 'javascript calculate age in years months days' in JavaScript

1
function age(birthday) {
2
  var ageDifMs = Date.now() - birthday.getTime();
3
  var ageDate = new Date(ageDifMs);
4
  return Math.abs(ageDate.getUTCFullYear() - 1970);
5
}

52
export function ageAsOf(birthDate, date) {
53
  if (!birthDate || !date || !birthDate.isValid() || !date.isValid()) {
54
    return null;
55
  }
56
57
  const onOrAfterBirthday = (
58
    date.month() > birthDate.month() || (
59
      date.month() === birthDate.month()
60
      && date.date() >= birthDate.date()
61
    )
62
  );
63
64
  return (date.year() - birthDate.year() - (onOrAfterBirthday ? 0 : 1));
65
}

44
function getDaysInMonth(year, month) {
45
	return 32 - new Date(UTC(year, month, 32)).getUTCDate();
46
};

114
export function addYears (d, years) {
115
  const newDate = cloneDate(d);
116
  newDate.setFullYear(d.getFullYear() + years);
117
  return newDate;
118
}

87
function calcAges() {
88
			var HOUR = 60 * 60 * 1000;
89
			var DAY = HOUR * 24;
90
			var WEEK = DAY * 7;
91
			var MONTH = DAY * 30;
92
			var YEAR = DAY * 365;
93
			
94
            var elts = document.getElementsByTagName("time");
95
			var elt;
96
			for (var i = 0; elt = elts[i]; i++) {
97
				elt.title = elt.textContent || elt.innerHTML;
98
				var iso = elt.getAttribute("datetime");
99
				var date = new Date(iso);
100
				var now = new Date();
101
				var diff = now.getTime() - date.getTime();
102
				var str = elt.innerHTML;
103
				if (diff > YEAR) str = toAge(diff / YEAR, "năm");
104
				else if (diff > MONTH) str = toAge(diff / MONTH, "tháng");
105
				else if (diff > WEEK) str = toAge(diff / WEEK, "tuần", true);
106
				else if (diff > DAY) str = toAge(diff / DAY, "ngày", true);
107
				else if (diff > HOUR) str = toAge(diff / HOUR, "tiếng", true);
108
				else str = "Mới bây giờ";
109
				elt.innerHTML = str;
110
			}
111
		}

36
function daysInYear(year) {
37
	return isLeapYear(year) ? 366 : 365;
38
}

100
function days_before_month(year, month) {
101
    var post_leap_feb = month > 2 && is_leap(year);
102
    return DAYS_BEFORE_MONTH[month] + (post_leap_feb ? 1 : 0);
103
}