Develop Reference

How to check if date is in this week in javascript?

I have this date "2016-04-23T11:45:00Z" and I want to check this date in this week or not ?
Thanks,

Dates are hard, I would always suggest using a library dedicated to date handling as it reduces the chances of errors in your code.
MomentJS is a good one.
var now = moment();
var input = moment("2016-04-17T11:45:00Z");
var isThisWeek = (now.isoWeek() == input.isoWeek())
Edit: Please note as of 2020 moment may not be a good choice for new projects

This seems to be working for me.
function isDateInThisWeek(date) {
const todayObj = new Date();
const todayDate = todayObj.getDate();
const todayDay = todayObj.getDay();
// get first date of week
const firstDayOfWeek = new Date(todayObj.setDate(todayDate - todayDay));
// get last date of week
const lastDayOfWeek = new Date(firstDayOfWeek);
lastDayOfWeek.setDate(lastDayOfWeek.getDate() + 6);
// if date is equal or within the first and last dates of the week
return date >= firstDayOfWeek && date <= lastDayOfWeek;
}
const date = new Date();
const isInWeek = isDateInThisWeek(date);

<div ng-app="myApp">
<div class="container" ng-controller="Ctrl_List">
<h1>{{currentDate}}</h1>
<h1>{{numberCurrentDateWeeks}}</h1>
<h1>{{yourDate}}</h1>
<h1>{{numberYourDateWeeks}}</h1>
</div>
</div>
......
angular.module('myApp', [])
.controller("Ctrl_List", ["$scope", "$filter", function(s, $filter) {
s.yourDate = '2016-04-23T11:45:00Z'
s.currentDate = new Date();
s.numberCurrentDateWeeks = $filter('date')(s.currentDate, "w");
s.numberYourDateWeeks = $filter('date')(s.yourDate, "w");
}]);
then you got the Week numbers just compare or do whatever you like
cheers !

You can do that without any libraries by checking if the date.getTime() (milliseconds since epoch) is between last monday and next monday:
const WEEK_LENGTH = 604800000;
function onCurrentWeek(date) {
var lastMonday = new Date(); // Creating new date object for today
lastMonday.setDate(lastMonday.getDate() - (lastMonday.getDay()-1)); // Setting date to last monday
lastMonday.setHours(0,0,0,0); // Setting Hour to 00:00:00:00
const res = lastMonday.getTime() <= date.getTime() &&
date.getTime() < ( lastMonday.getTime() + WEEK_LENGTH);
return res; // true / false
}
(one week in ms = 24 * 60 * 60 * 1000 * 7 = 604,800,000)

May not be the most optimal solution, but I think it's quite readable:
function isThisWeek (date) {
const now = new Date();
const weekDay = (now.getDay() + 6) % 7; // Make sure Sunday is 6, not 0
const monthDay = now.getDate();
const mondayThisWeek = monthDay - weekDay;
const startOfThisWeek = new Date(+now);
startOfThisWeek.setDate(mondayThisWeek);
startOfThisWeek.setHours(0, 0, 0, 0);
const startOfNextWeek = new Date(+startOfThisWeek);
startOfNextWeek.setDate(mondayThisWeek + 7);
return date >= startOfThisWeek && date < startOfNextWeek;
}

This link explaines, how to do this without using any js libraries. https://gist.github.com/dblock/1081513
Code against link death:
function( d ) {
// Create a copy of this date object
var target = new Date(d.valueOf());
// ISO week date weeks start on monday
// so correct the day number
var dayNr = (d.getDay() + 6) % 7;
// Set the target to the thursday of this week so the
// target date is in the right year
target.setDate(target.getDate() - dayNr + 3);
// ISO 8601 states that week 1 is the week
// with january 4th in it
var jan4 = new Date(target.getFullYear(), 0, 4);
// Number of days between target date and january 4th
var dayDiff = (target - jan4) / 86400000;
// Calculate week number: Week 1 (january 4th) plus the
// number of weeks between target date and january 4th
var weekNr = 1 + Math.ceil(dayDiff / 7);
return weekNr;
}

I managed to do it with this simple trick and without any external library.
Considering monday as the first day of the week, the function takes as parameter a date string and do the validation before checking if the day indeed is in the current week.
function isInThisWeek(livr){
const WEEK = new Date()
// convert delivery date to Date instance
const DATEREF = new Date(livr)
// Check if date instance is in valid format (depends on the function arg)
if(DATEREF instanceof Date && isNaN(DATEREF)){
console.log("invalid date format")
return false}
// Deconstruct to get separated date infos
const [dayR, monthR, yearR] = [DATEREF.getDate(), DATEREF.getMonth(), DATEREF.getFullYear()]
// get Monday date
const monday = (WEEK.getDate() - WEEK.getDay()) + 1
// get Saturday date
const sunday = monday + 6
// Start verification
if (yearR !== WEEK.getFullYear()) { console.log("WRONG YEAR"); return false }
if (monthR !== WEEK.getMonth()) { console.log("WRONG MONTH"); return false }
if(dayR >= monday && dayR <= sunday) { return true }
else {console.log("WRONG DAY"); return false}
}

In the comments I saw that you stated that your week starts on Monday.
In that case, I guess it'd be a good idea to calculate the ISO week number of the 2 dates and see if you get the same week number for both of them.
To calculate the ISO week number, check this answer:
In case anyone else's week starts on Sunday instead, you can use this answer to calculate the week number accordingly.
then you can do something like this:
function isSameWeek(date1, date2) {
return date1.getWeekNumber() === date2.getWeekNumber();
}

const isDateInThisWeek = (date) => {
const today = new Date();
//Get the first day of the current week (Sunday)
const firstDayOfWeek = new Date(
today.setDate(today.getDate() - today.getDay())
);
//Get the last day of the current week (Saturday)
const lastDayOfWeek = new Date(
today.setDate(today.getDate() - today.getDay() + 6)
);
//check if my value is between a minimum date and a maximum date
if (date >= firstDayOfWeek && date <= lastDayOfWeek) {
return true;
} else {
return false;
}
};

get date with of a day with respect to a given date

I am trying to get the date of a day with respect to a particular date. Suppose i give A=date(22/07/2014) and sunday as input then the output should be date of coming sunday with respect to A date here the output will be 27 july.
Thanks in advance
edit: merge comment
tried with
dayto=7;
var td = new Date();
var nextSunday= new Date( td.getFullYear(),
td.getMonth(),
td.getDate() + (dayto-td.getDay()) );
but it returns in respect to today's date and if i change td variable with any other date then it do not works

This will do the job
<script>
var days = ['Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday'];
function findDayDate(date, dayInput) {
var d = new Date(Date.parse(date));
var day = days[ d.getDay() ];
while(true) {
if (day.toLowerCase() === dayInput.toLowerCase()) {
break;
} else {
d.setDate(d.getDate() + 1);
day = days[ d.getDay() ];
}
}
return d;
}
document.write(findDayDate("2005-07-08", "sunday"));
</script>

Check if one date is between two dates

I need to check if a date - a string in dd/mm/yyyy format -
falls between two other dates having the same format dd/mm/yyyy
I tried this, but it doesn't work:
var dateFrom = "02/05/2013";
var dateTo = "02/09/2013";
var dateCheck = "02/07/2013";
var from = Date.parse(dateFrom);
var to = Date.parse(dateTo);
var check = Date.parse(dateCheck );
if((check <= to && check >= from))
alert("date contained");
I used debugger and checked, the to and from variables have isNaN value.
Could you help me?

Date.parse supports the format mm/dd/yyyy not dd/mm/yyyy. For the latter, either use a library like moment.js or do something as shown below
var dateFrom = "02/05/2013";
var dateTo = "02/09/2013";
var dateCheck = "02/07/2013";
var d1 = dateFrom.split("/");
var d2 = dateTo.split("/");
var c = dateCheck.split("/");
var from = new Date(d1[2], parseInt(d1[1])-1, d1[0]); // -1 because months are from 0 to 11
var to = new Date(d2[2], parseInt(d2[1])-1, d2[0]);
var check = new Date(c[2], parseInt(c[1])-1, c[0]);
console.log(check > from && check < to)

Instead of comparing the dates directly, compare the getTime() value of the date. The getTime() function returns the number of milliseconds since Jan 1, 1970 as an integer-- should be trivial to determine if one integer falls between two other integers.
Something like
if((check.getTime() <= to.getTime() && check.getTime() >= from.getTime())) alert("date contained");

Try what's below. It will help you...
Fiddle : http://jsfiddle.net/RYh7U/146/
Script :
if(dateCheck("02/05/2013","02/09/2013","02/07/2013"))
alert("Availed");
else
alert("Not Availed");
function dateCheck(from,to,check) {
var fDate,lDate,cDate;
fDate = Date.parse(from);
lDate = Date.parse(to);
cDate = Date.parse(check);
if((cDate <= lDate && cDate >= fDate)) {
return true;
}
return false;
}

The answer that has 50 votes doesn't check for date in only checks for months. That answer is not correct. The code below works.
var dateFrom = "01/08/2017";
var dateTo = "01/10/2017";
var dateCheck = "05/09/2017";
var d1 = dateFrom.split("/");
var d2 = dateTo.split("/");
var c = dateCheck.split("/");
var from = new Date(d1); // -1 because months are from 0 to 11
var to = new Date(d2);
var check = new Date(c);
alert(check > from && check < to);
This is the code posted in another answer and I have changed the dates and that's how I noticed it doesn't work
var dateFrom = "02/05/2013";
var dateTo = "02/09/2013";
var dateCheck = "07/07/2013";
var d1 = dateFrom.split("/");
var d2 = dateTo.split("/");
var c = dateCheck.split("/");
var from = new Date(d1[2], parseInt(d1[1])-1, d1[0]); // -1 because months are from 0 to 11
var to = new Date(d2[2], parseInt(d2[1])-1, d2[0]);
var check = new Date(c[2], parseInt(c[1])-1, c[0]);
alert(check > from && check < to);

Simplified way of doing this based on the accepted answer.
In my case I needed to check if current date (Today) is pithing the range of two other dates so used newDate() instead of hardcoded values but you can get the point how you can use hardcoded dates.
var currentDate = new Date().toJSON().slice(0,10);
var from = new Date('2020/01/01');
var to = new Date('2020/01/31');
var check = new Date(currentDate);
console.log(check > from && check < to);

I have created customize function to validate given date is between two dates or not.
var getvalidDate = function(d){ return new Date(d) }
function validateDateBetweenTwoDates(fromDate,toDate,givenDate){
return getvalidDate(givenDate) <= getvalidDate(toDate) && getvalidDate(givenDate) >= getvalidDate(fromDate);
}

Here is a Date Prototype method written in typescript:
Date.prototype.isBetween = isBetween;
interface Date { isBetween: typeof isBetween }
function isBetween(minDate: Date, maxDate: Date): boolean {
if (!this.getTime) throw new Error('isBetween() was called on a non Date object');
return !minDate ? true : this.getTime() >= minDate.getTime()
&& !maxDate ? true : this.getTime() <= maxDate.getTime();
};

I did the same thing that #Diode, the first answer, but i made the condition with a range of dates, i hope this example going to be useful for someone
e.g (the same code to example with array of dates)
var dateFrom = "02/06/2013";
var dateTo = "02/09/2013";
var d1 = dateFrom.split("/");
var d2 = dateTo.split("/");
var from = new Date(d1[2], parseInt(d1[1])-1, d1[0]); // -1 because months are from 0 to 11
var to = new Date(d2[2], parseInt(d2[1])-1, d2[0]);
var dates= ["02/06/2013", "02/07/2013", "02/08/2013", "02/09/2013", "02/07/2013", "02/10/2013", "02/011/2013"];
dates.forEach(element => {
let parts = element.split("/");
let date= new Date(parts[2], parseInt(parts[1]) - 1, parts[0]);
if (date >= from && date < to) {
console.log('dates in range', date);
}
})

Try this:
HTML
<div id="eventCheck"></div>
JAVASCRIPT
// ----------------------------------------------------//
// Todays date
var today = new Date();
var dd = today.getDate();
var mm = today.getMonth()+1; //January is 0!
var yyyy = today.getFullYear();
// Add Zero if it number is between 0-9
if(dd<10) {
dd = '0'+dd;
}
if(mm<10) {
mm = '0'+mm;
}
var today = yyyy + '' + mm + '' + dd ;
// ----------------------------------------------------//
// Day of event
var endDay = 15; // day 15
var endMonth = 01; // month 01 (January)
var endYear = 2017; // year 2017
// Add Zero if it number is between 0-9
if(endDay<10) {
endDay = '0'+endDay;
}
if(endMonth<10) {
endMonth = '0'+endMonth;
}
// eventDay - date of the event
var eventDay = endYear + '/' + endMonth + '/' + endDay;
// ----------------------------------------------------//
// ----------------------------------------------------//
// check if eventDay has been or not
if ( eventDay < today ) {
document.getElementById('eventCheck').innerHTML += 'Date has passed (event is over)'; // true
} else {
document.getElementById('eventCheck').innerHTML += 'Date has not passed (upcoming event)'; // false
}
Fiddle:
https://jsfiddle.net/zm75cq2a/

Suppose for example your date is coming like this & you need to install momentjs for advance date features.
let cmpDate = Thu Aug 27 2020 00:00:00 GMT+0530 (India Standard Time)
let format = "MM/DD/YYYY";
let startDate: any = moment().format(format);
let endDate: any = moment().add(30, "days").format(format);
let compareDate: any = moment(cmpDate).format(format);
var startDate1 = startDate.split("/");
var startDate2 = endDate.split("/");
var compareDate1 = compareDate.split("/");
var fromDate = new Date(startDate1[2], parseInt(startDate1[1]) - 1, startDate1[0]);
var toDate = new Date(startDate2[2], parseInt(startDate2[1]) - 1, startDate2[0]);
var checkDate = new Date(compareDate1[2], parseInt(compareDate1[1]) - 1, compareDate1[0]);
if (checkDate > fromDate && checkDate < toDate) {
... condition works between current date to next 30 days
}

This may feel a bit more intuitive. The parameter is just a valid date string.
This function returns true if the date passed as argument is in the current week, or false if not.
function isInThisWeek(dateToCheck){
// Create a brand new Date instance
const WEEK = new Date()
// create a date instance with the function parameter
//(format should be like dd/mm/yyyy or any javascript valid date format )
const DATEREF = new Date(dateToCheck)
// If the parameter is a not a valid date, return false
if(DATEREF instanceof Date && isNaN(DATEREF)){
console.log("invalid date format")
return false}
// Get separated date infos (the date of today, the current month and the current year) based on the date given as parameter
const [dayR, monthR, yearR] = [DATEREF.getDate(), DATEREF.getMonth(), DATEREF.getFullYear()]
// get Monday date by substracting the day index (number) in the week from the day value (count)
//in the month (like october 15th - 5 (-> saturday index)) and +1 because
//JS weirdly starts the week on sundays
const monday = (WEEK.getDate() - WEEK.getDay()) + 1
// get Saturday date
const sunday = monday + 6
// Start verification
if (yearR !== WEEK.getFullYear()) { console.log("WRONG YEAR"); return false }
if (monthR !== WEEK.getMonth()) { console.log("WRONG MONTH"); return false }
if(dayR >= monday && dayR <= sunday) { return true }
else {console.log("WRONG DAY"); return false}
}

Try this
var gdate='01-05-2014';
date =Date.parse(gdate.split('-')[1]+'-'+gdate.split('-')[0]+'-'+gdate.split('-')[2]);
if(parseInt(date) < parseInt(Date.now()))
{
alert('small');
}else{
alert('big');
}
Fiddle

This question is very generic, hence people who are using date libraries also check for the answer, but I couldn't find any answer for the date libraries, hence I am posting the answer for Luxon users.
const fromDate = '2022-06-01T00:00:00.000Z';
const toDate = '2022-06-30T23:59:59.999Z';
const inputDate = '2022-08-09T20:26:13.380Z';
if (
DateTime.fromISO(inputDate) >= DateTime.fromISO(fromDate) &&
DateTime.fromISO(inputDate) <= DateTime.fromISO(toDate)
) {
console.log('within range');
} else {
console.log('not in range');
}

Check if a date within in range

I am trying to check if a date of format mm.dd.yyyy is greater than today and less than the date after 6 months from today.
Here is my code:
var isLinkExpiryDateWithinRange = function(value) {
var monthfield = value.split('.')[0];
var dayfield = value.split('.')[1];
var yearfield = value.split('.')[2];
var inputDate = new Date(yearfield, monthfield - 1, dayfield);
var today = new Date();
today = new Date(today.getFullYear(), today.getMonth(), today.getDate());
alert(inputDate > today);//alert-> true
var endDate = today;
endDate.setMonth(endDate.getMonth() + 6);
alert(inputDate > today);//alert-> false
if(inputDate > today && inputDate < endDate) {
alert('1');
} else {
alert('2');/always alert it
}
}
If I execute isLinkExpiryDateWithinRange('12.08.2012') I wish it will show 1 as this is within the range, but it is displaying 2. Moreover the first alert is showing true and the second one false.
Can anyone please explain what is happening?

Change:
var endDate = today;
to:
var endDate = new Date(today);
See the posts here for how objects are referenced and changed. There are some really good examples that help explain the issue, notably:
Instead, the situation is that the item passed in is passed by value.
But the item that is passed by value is itself a reference.
JSFiddle example

function isLinkExpiryDateWithinRange( value ) {
// format: mm.dd.yyyy;
value = value.split(".");
var todayDate = new Date(),
endDate = new Date( todayDate.getFullYear(), todayDate.getMonth() + 6, todayDate.getDate() +1 );
date = new Date(value[2], value[0]-1, value[1]);
return todayDate < date && date < endDate;
}
isLinkExpiryDateWithinRange("12.24.2012"); // true
isLinkExpiryDateWithinRange("12.24.2020"); // false

Below function checks if date selected is within 5 days from today. Date format used is "DD-MM-YYYY", you can use any format by changing value.split('-')[1] order and split character.
function showMessage() {
var value = document.getElementById("invoiceDueDate").value;
var inputDate = new Date(value.split('-')[2], value.split('-')[1] - 1, value.split('-')[0]);
var endDate = new Date();
endDate.setDate(endDate.getDate() + 5);// adding 5 days from today
if(inputDate < endDate) {
alert("If the due date selected for the invoice is within 5 days, and express settlement fee will apply to this transaction.");
}
}

How can I calculate the number of years between two dates?

I want to get the number of years between two dates. I can get the number of days between these two days, but if I divide it by 365 the result is incorrect because some years have 366 days.
This is my code to get date difference:
var birthday = value;//format 01/02/1900
var dateParts = birthday.split("/");
var checkindate = new Date(dateParts[2], dateParts[0] - 1, dateParts[1]);
var now = new Date();
var difference = now - checkindate;
var days = difference / (1000*60*60*24);
var thisyear = new Date().getFullYear();
var birthyear = dateParts[2];
var number_of_long_years = 0;
for(var y=birthyear; y <= thisyear; y++){
if( (y % 4 == 0 && y % 100 == 0) || y % 400 == 0 ) {
number_of_long_years++;
}
}
The day count works perfectly. I am trying to do add the additional days when it is a 366-day year, and I'm doing something like this:
var years = ((days)*(thisyear-birthyear))
/((number_of_long_years*366) + ((thisyear-birthyear-number_of_long_years)*365) );
I'm getting the year count. Is this correct, or is there a better way to do this?

Sleek foundation javascript function.
function calculateAge(birthday) { // birthday is a date
var ageDifMs = Date.now() - birthday;
var ageDate = new Date(ageDifMs); // miliseconds from epoch
return Math.abs(ageDate.getUTCFullYear() - 1970);
}

Probably not the answer you're looking for, but at 2.6kb, I would not try to reinvent the wheel and I'd use something like moment.js. Does not have any dependencies.
The diff method is probably what you want: http://momentjs.com/docs/#/displaying/difference/

Using pure javascript Date(), we can calculate the numbers of years like below
document.getElementById('getYearsBtn').addEventListener('click', function () {
var enteredDate = document.getElementById('sampleDate').value;
// Below one is the single line logic to calculate the no. of years...
var years = new Date(new Date() - new Date(enteredDate)).getFullYear() - 1970;
console.log(years);
});
<input type="text" id="sampleDate" value="1980/01/01">
<div>Format: yyyy-mm-dd or yyyy/mm/dd</div><br>
<button id="getYearsBtn">Calculate Years</button>

No for-each loop, no extra jQuery plugin needed... Just call the below function.. Got from Difference between two dates in years
function dateDiffInYears(dateold, datenew) {
var ynew = datenew.getFullYear();
var mnew = datenew.getMonth();
var dnew = datenew.getDate();
var yold = dateold.getFullYear();
var mold = dateold.getMonth();
var dold = dateold.getDate();
var diff = ynew - yold;
if (mold > mnew) diff--;
else {
if (mold == mnew) {
if (dold > dnew) diff--;
}
}
return diff;
}

I use the following for age calculation.
I named it gregorianAge() because this calculation gives exactly how we denote age using Gregorian calendar. i.e. Not counting the end year if month and day is before the month and day of the birth year.
/**
* Calculates human age in years given a birth day. Optionally ageAtDate
* can be provided to calculate age at a specific date
*
* #param string|Date Object birthDate
* #param string|Date Object ageAtDate optional
* #returns integer Age between birthday and a given date or today
*/
gregorianAge = function(birthDate, ageAtDate) {
// convert birthDate to date object if already not
if (Object.prototype.toString.call(birthDate) !== '[object Date]')
birthDate = new Date(birthDate);
// use today's date if ageAtDate is not provided
if (typeof ageAtDate == "undefined")
ageAtDate = new Date();
// convert ageAtDate to date object if already not
else if (Object.prototype.toString.call(ageAtDate) !== '[object Date]')
ageAtDate = new Date(ageAtDate);
// if conversion to date object fails return null
if (ageAtDate == null || birthDate == null)
return null;
var _m = ageAtDate.getMonth() - birthDate.getMonth();
// answer: ageAt year minus birth year less one (1) if month and day of
// ageAt year is before month and day of birth year
return (ageAtDate.getFullYear()) - birthDate.getFullYear()
- ((_m < 0 || (_m === 0 && ageAtDate.getDate() < birthDate.getDate()))?1:0)
}
<input type="text" id="birthDate" value="12 February 1982">
<div style="font-size: small; color: grey">Enter a date in an acceptable format e.g. 10 Dec 2001</div><br>
<button onClick='js:alert(gregorianAge(document.getElementById("birthDate").value))'>What's my age?</button>

Little out of date but here is a function you can use!
function calculateAge(birthMonth, birthDay, birthYear) {
var currentDate = new Date();
var currentYear = currentDate.getFullYear();
var currentMonth = currentDate.getMonth();
var currentDay = currentDate.getDate();
var calculatedAge = currentYear - birthYear;
if (currentMonth < birthMonth - 1) {
calculatedAge--;
}
if (birthMonth - 1 == currentMonth && currentDay < birthDay) {
calculatedAge--;
}
return calculatedAge;
}
var age = calculateAge(12, 8, 1993);
alert(age);

You can get the exact age using timesstamp:
const getAge = (dateOfBirth, dateToCalculate = new Date()) => {
const dob = new Date(dateOfBirth).getTime();
const dateToCompare = new Date(dateToCalculate).getTime();
const age = (dateToCompare - dob) / (365 * 24 * 60 * 60 * 1000);
return Math.floor(age);
};

let currentTime = new Date().getTime();
let birthDateTime= new Date(birthDate).getTime();
let difference = (currentTime - birthDateTime)
var ageInYears=difference/(1000*60*60*24*365)

Yep, moment.js is pretty good for this:
var moment = require('moment');
var startDate = new Date();
var endDate = new Date();
endDate.setDate(endDate.getFullYear() + 5); // Add 5 years to second date
console.log(moment.duration(endDate - startDate).years()); // This should returns 5

getYears(date1, date2) {
let years = new Date(date1).getFullYear() - new Date(date2).getFullYear();
let month = new Date(date1).getMonth() - new Date(date2).getMonth();
let dateDiff = new Date(date1).getDay() - new Date(date2).getDay();
if (dateDiff < 0) {
month -= 1;
}
if (month < 0) {
years -= 1;
}
return years;
}

for(var y=birthyear; y <= thisyear; y++){
if( (y % 4 == 0 && y % 100 == 0) || y % 400 == 0 ) {
days = days-366;
number_of_long_years++;
} else {
days=days-365;
}
year++;
}
can you try this way??

function getYearDiff(startDate, endDate) {
let yearDiff = endDate.getFullYear() - startDate.getFullYear();
if (startDate.getMonth() > endDate.getMonth()) {
yearDiff--;
} else if (startDate.getMonth() === endDate.getMonth()) {
if (startDate.getDate() > endDate.getDate()) {
yearDiff--;
} else if (startDate.getDate() === endDate.getDate()) {
if (startDate.getHours() > endDate.getHours()) {
yearDiff--;
} else if (startDate.getHours() === endDate.getHours()) {
if (startDate.getMinutes() > endDate.getMinutes()) {
yearDiff--;
}
}
}
}
return yearDiff;
}
alert(getYearDiff(firstDate, secondDate));

getAge(month, day, year) {
let yearNow = new Date().getFullYear();
let monthNow = new Date().getMonth() + 1;
let dayNow = new Date().getDate();
if (monthNow === month && dayNow < day || monthNow < month) {
return yearNow - year - 1;
} else {
return yearNow - year;
}
}

If you are using moment
/**
* Convert date of birth into age
* param {string} dateOfBirth - date of birth
* param {string} dateToCalculate - date to compare
* returns {number} - age
*/
function getAge(dateOfBirth, dateToCalculate) {
const dob = moment(dateOfBirth);
return moment(dateToCalculate).diff(dob, 'years');
};

If you want to calculate the years and keep the remainder of the time left for further calculations you can use this function most of the other answers discard the remaining time.
It returns the years and the remainder in milliseconds. This is useful if you want to calculate the time (days or minutes) left after you calculate the years.
The function works by first calculating the difference in years directly using *date.getFullYear()*.
Then it checks if the last year between the two dates is up to a full year by setting the two dates to the same year.
Eg:
oldDate= 1 July 2020,
newDate= 1 June 2022,
years =2020 -2022 =2
Now set old date to new date's year 2022
oldDate = 1 July, 2022
If the last year is not up to a full year then the year is subtracted by 1, the old date is set to the previous year and the interval from the previous year to the current date is calculated to give the remainder in milliseconds.
In the example since old date July 2022 is greater than June 2022 then it means a full year has not yet elapsed (from July 2021 to June 2022) therefore the year count is greater by 1. So years should be decreased by 1. And the actual year count from July 2020 to June 2022 is 1 year ,... months.
If the last year is a full year then the year count by *date.getFullYear()* is correct and the time that has elapsed from the current old date to new date is calculated as the remainder.
If old date= 1 April, 2020, new date = 1 June, 2022 and old date is set to April 2022 after calculating the year =2.
Eg: from April 2020 to June 2022 a duration of 2 years has passed with the remainder being the time from April 2022 to June 2022.
There are also checks for cases where the two dates are in the same year and if the user enters the dates in the wrong order the new Date is less recent than the old Date.
let getYearsAndRemainder = (newDate, oldDate) => {
let remainder = 0;
// get initial years between dates
let years = newDate.getFullYear() - oldDate.getFullYear();
if (years < 0) {// check to make sure the oldDate is the older of the two dates
console.warn('new date is lesser than old date in year difference')
years = 0;
} else {
// set the old date to the same year as new date
oldDate.setFullYear(newDate.getFullYear());
// check if the old date is less than new date in the same year
if (oldDate - newDate > 0) {
//if true, the old date is greater than the new date
// the last but one year between the two dates is not up to a year
if (years != 0) {// dates given in inputs are in the same year, no need to calculate years if the number of years is 0
console.log('Subtracting year');
//set the old year to the previous year
years--;
oldDate.setFullYear(oldDate.getFullYear() - 1);
}
}
}
//calculate the time difference between the old year and newDate.
remainder = newDate - oldDate;
if (remainder < 0) { //check for negative dates due to wrong inputs
console.warn('old date is greater than new Date');
console.log('new date', newDate, 'old date', oldDate);
}
return { years, remainder };
}
let old = new Date('2020-07-01');
console.log( getYearsAndRemainder(new Date(), old));

Date calculation work via the Julian day number. You have to take the first of January of the two years. Then you convert the Gregorian dates into Julian day numbers and after that you take just the difference.

Maybe my function can explain better how to do this in a simple way without loop, calculations and/or libs
function checkYearsDifference(birthDayDate){
var todayDate = new Date();
var thisMonth = todayDate.getMonth();
var thisYear = todayDate.getFullYear();
var thisDay = todayDate.getDate();
var monthBirthday = birthDayDate.getMonth();
var yearBirthday = birthDayDate.getFullYear();
var dayBirthday = birthDayDate.getDate();
//first just make the difference between years
var yearDifference = thisYear - yearBirthday;
//then check months
if (thisMonth == monthBirthday){
//if months are the same then check days
if (thisDay<dayBirthday){
//if today day is before birthday day
//then I have to remove 1 year
//(no birthday yet)
yearDifference = yearDifference -1;
}
//if not no action because year difference is ok
}
else {
if (thisMonth < monthBirthday) {
//if actual month is before birthday one
//then I have to remove 1 year
yearDifference = yearDifference -1;
}
//if not no action because year difference is ok
}
return yearDifference;
}

Bro, moment.js is awesome for this:
The diff method is what you want: http://momentjs.com/docs/#/displaying/difference/
The below function return array of years from the year to the current year.
const getYears = (from = 2017) => {
const diff = moment(new Date()).diff(new Date(`01/01/${from}`), 'years') ;
return [...Array(diff >= 0 ? diff + 1 : 0).keys()].map((num) => {
return from + num;
});
}
console.log(getYears(2016));
<script src="https://momentjs.com/downloads/moment.js"></script>

function dateDiffYearsOnly( dateNew,dateOld) {
function date2ymd(d){ w=new Date(d);return [w.getFullYear(),w.getMonth(),w.getDate()]}
function ymd2N(y){return (((y[0]<<4)+y[1])<<5)+y[2]} // or 60 and 60 // or 13 and 32 // or 25 and 40 //// with ...
function date2N(d){ return ymd2N(date2ymd(d))}
return (date2N(dateNew)-date2N(dateOld))>>9
}
test:
dateDiffYearsOnly(Date.now(),new Date(Date.now()-7*366*24*3600*1000));
dateDiffYearsOnly(Date.now(),new Date(Date.now()-7*365*24*3600*1000))

I went for the following very simple solution. It does not assume you were born in 1970 and it also takes into account the hour of the given birthday date.
function age(birthday) {
let now = new Date();
let year = now.getFullYear();
let years = year - birthday.getFullYear();
birthday = new Date(birthday.getTime()); // clone
birthday.setFullYear(year);
return now >= birthday ? years : years - 1;
}

This one Help you...
$("[id$=btnSubmit]").click(function () {
debugger
var SDate = $("[id$=txtStartDate]").val().split('-');
var Smonth = SDate[0];
var Sday = SDate[1];
var Syear = SDate[2];
// alert(Syear); alert(Sday); alert(Smonth);
var EDate = $("[id$=txtEndDate]").val().split('-');
var Emonth = EDate[0];
var Eday = EDate[1];
var Eyear = EDate[2];
var y = parseInt(Eyear) - parseInt(Syear);
var m, d;
if ((parseInt(Emonth) - parseInt(Smonth)) > 0) {
m = parseInt(Emonth) - parseInt(Smonth);
}
else {
m = parseInt(Emonth) + 12 - parseInt(Smonth);
y = y - 1;
}
if ((parseInt(Eday) - parseInt(Sday)) > 0) {
d = parseInt(Eday) - parseInt(Sday);
}
else {
d = parseInt(Eday) + 30 - parseInt(Sday);
m = m - 1;
}
// alert(y + " " + m + " " + d);
$("[id$=lblAge]").text("your age is " + y + "years " + m + "month " + d + "days");
return false;
});

if someone needs for interest calculation year in float format
function floatYearDiff(olddate, newdate) {
var new_y = newdate.getFullYear();
var old_y = olddate.getFullYear();
var diff_y = new_y - old_y;
var start_year = new Date(olddate);
var end_year = new Date(olddate);
start_year.setFullYear(new_y);
end_year.setFullYear(new_y+1);
if (start_year > newdate) {
start_year.setFullYear(new_y-1);
end_year.setFullYear(new_y);
diff_y--;
}
var diff = diff_y + (newdate - start_year)/(end_year - start_year);
return diff;
}