Develop Reference

Date overdue pop up alert not working with "IF" statement [duplicate]

Can someone suggest a way to compare the values of two dates greater than, less than, and not in the past using JavaScript? The values will be coming from text boxes.

The Date object will do what you want - construct one for each date, then compare them using the >, <, <= or >=.
The ==, !=, ===, and !== operators require you to use date.getTime() as in
var d1 = new Date();
var d2 = new Date(d1);
var same = d1.getTime() === d2.getTime();
var notSame = d1.getTime() !== d2.getTime();
to be clear just checking for equality directly with the date objects won't work
var d1 = new Date();
var d2 = new Date(d1);
console.log(d1 == d2); // prints false (wrong!)
console.log(d1 === d2); // prints false (wrong!)
console.log(d1 != d2); // prints true (wrong!)
console.log(d1 !== d2); // prints true (wrong!)
console.log(d1.getTime() === d2.getTime()); // prints true (correct)
I suggest you use drop-downs or some similar constrained form of date entry rather than text boxes, though, lest you find yourself in input validation hell.
For the curious, date.getTime() documentation:
Returns the numeric value of the specified date as the number of milliseconds since January 1, 1970, 00:00:00 UTC. (Negative values are returned for prior times.)

Compare < and > just as usual, but anything involving == or === should use a + prefix. Like so:
const x = new Date('2013-05-23');
const y = new Date('2013-05-23');
// less than, greater than is fine:
console.log('x < y', x < y); // false
console.log('x > y', x > y); // false
console.log('x <= y', x <= y); // true
console.log('x >= y', x >= y); // true
console.log('x === y', x === y); // false, oops!
// anything involving '==' or '===' should use the '+' prefix
// it will then compare the dates' millisecond values
console.log('+x === +y', +x === +y); // true

The easiest way to compare dates in javascript is to first convert it to a Date object and then compare these date-objects.
Below you find an object with three functions:
dates.compare(a,b)
Returns a number:
-1 if a < b
0 if a = b
1 if a > b
NaN if a or b is an illegal date
dates.inRange (d,start,end)
Returns a boolean or NaN:
true if d is between the start and end (inclusive)
false if d is before start or after end.
NaN if one or more of the dates are illegal.
dates.convert
Used by the other functions to convert their input to a date object. The input can be
a date-object : The input is returned as is.
an array: Interpreted as [year,month,day]. NOTE month is 0-11.
a number : Interpreted as number of milliseconds since 1 Jan 1970 (a timestamp)
a string : Several different formats is supported, like "YYYY/MM/DD", "MM/DD/YYYY", "Jan 31 2009" etc.
an object: Interpreted as an object with year, month and date attributes. NOTE month is 0-11.
.
// Source: http://stackoverflow.com/questions/497790
var dates = {
convert:function(d) {
// Converts the date in d to a date-object. The input can be:
// a date object: returned without modification
// an array : Interpreted as [year,month,day]. NOTE: month is 0-11.
// a number : Interpreted as number of milliseconds
// since 1 Jan 1970 (a timestamp)
// a string : Any format supported by the javascript engine, like
// "YYYY/MM/DD", "MM/DD/YYYY", "Jan 31 2009" etc.
// an object : Interpreted as an object with year, month and date
// attributes. **NOTE** month is 0-11.
return (
d.constructor === Date ? d :
d.constructor === Array ? new Date(d[0],d[1],d[2]) :
d.constructor === Number ? new Date(d) :
d.constructor === String ? new Date(d) :
typeof d === "object" ? new Date(d.year,d.month,d.date) :
NaN
);
},
compare:function(a,b) {
// Compare two dates (could be of any type supported by the convert
// function above) and returns:
// -1 : if a < b
// 0 : if a = b
// 1 : if a > b
// NaN : if a or b is an illegal date
// NOTE: The code inside isFinite does an assignment (=).
return (
isFinite(a=this.convert(a).valueOf()) &&
isFinite(b=this.convert(b).valueOf()) ?
(a>b)-(a<b) :
NaN
);
},
inRange:function(d,start,end) {
// Checks if date in d is between dates in start and end.
// Returns a boolean or NaN:
// true : if d is between start and end (inclusive)
// false : if d is before start or after end
// NaN : if one or more of the dates is illegal.
// NOTE: The code inside isFinite does an assignment (=).
return (
isFinite(d=this.convert(d).valueOf()) &&
isFinite(start=this.convert(start).valueOf()) &&
isFinite(end=this.convert(end).valueOf()) ?
start <= d && d <= end :
NaN
);
}
}

The relational operators < <= > >= can be used to compare JavaScript dates:
var d1 = new Date(2013, 0, 1);
var d2 = new Date(2013, 0, 2);
d1 < d2; // true
d1 <= d2; // true
d1 > d2; // false
d1 >= d2; // false
However, the equality operators == != === !== cannot be used to compare (the value of) dates because:
Two distinct objects are never equal for either strict or abstract comparisons.
An expression comparing Objects is only true if the operands reference the same Object.
You can compare the value of dates for equality using any of these methods:
var d1 = new Date(2013, 0, 1);
var d2 = new Date(2013, 0, 1);
/*
* note: d1 == d2 returns false as described above
*/
d1.getTime() == d2.getTime(); // true
d1.valueOf() == d2.valueOf(); // true
Number(d1) == Number(d2); // true
+d1 == +d2; // true
Both Date.getTime() and Date.valueOf() return the number of milliseconds since January 1, 1970, 00:00 UTC. Both Number function and unary + operator call the valueOf() methods behind the scenes.

By far the easiest method is to subtract one date from the other and compare the result.
var oDateOne = new Date();
var oDateTwo = new Date();
alert(oDateOne - oDateTwo === 0);
alert(oDateOne - oDateTwo < 0);
alert(oDateOne - oDateTwo > 0);

Comparing dates in JavaScript is quite easy... JavaScript has built-in comparison system for dates which makes it so easy to do the comparison...
Just follow these steps for comparing 2 dates value, for example you have 2 inputs which each has a Date value in String and you to compare them...
1. you have 2 string values you get from an input and you'd like to compare them, they are as below:
var date1 = '01/12/2018';
var date2 = '12/12/2018';
2. They need to be Date Object to be compared as date values, so simply convert them to date, using new Date(), I just re-assign them for simplicity of explanation, but you can do it anyway you like:
date1 = new Date(date1);
date2 = new Date(date2);
3. Now simply compare them, using the > < >= <=
date1 > date2; //false
date1 < date2; //true
date1 >= date2; //false
date1 <= date2; //true

Compare day only (ignoring time component):
Date.prototype.sameDay = function(d) {
return this.getFullYear() === d.getFullYear()
&& this.getDate() === d.getDate()
&& this.getMonth() === d.getMonth();
}
Usage:
if(date1.sameDay(date2)) {
// highlight day on calendar or something else clever
}
I no longer recommend modifying the prototype of built-in objects. Try this instead:
function isSameDay(d1, d2) {
return d1.getFullYear() === d2.getFullYear() &&
d1.getDate() === d2.getDate() &&
d1.getMonth() === d2.getMonth();
}
console.log(isSameDay(new Date('Jan 15 2021 02:39:53 GMT-0800'), new Date('Jan 15 2021 23:39:53 GMT-0800')));
console.log(isSameDay(new Date('Jan 15 2021 10:39:53 GMT-0800'), new Date('Jan 16 2021 10:39:53 GMT-0800')));
N.B. the year/month/day will be returned for your timezone; I recommend using a timezone-aware library if you want to check if two dates are on the same day in a different timezone.
e.g.
> (new Date('Jan 15 2021 01:39:53 Z')).getDate() // Jan 15 in UTC
14 // Returns "14" because I'm in GMT-08

what format?
If you construct a Javascript Date object, you can just subtract them to get a milliseconds difference (edit: or just compare them) :
js>t1 = new Date()
Thu Jan 29 2009 14:19:28 GMT-0500 (Eastern Standard Time)
js>t2 = new Date()
Thu Jan 29 2009 14:19:31 GMT-0500 (Eastern Standard Time)
js>t2-t1
2672
js>t3 = new Date('2009 Jan 1')
Thu Jan 01 2009 00:00:00 GMT-0500 (Eastern Standard Time)
js>t1-t3
2470768442
js>t1>t3
true

Note - Compare Only Date Part:
When we compare two date in javascript. It takes hours, minutes and seconds also into consideration.. So If we only need to compare date only, this is the approach:
var date1= new Date("01/01/2014").setHours(0,0,0,0);
var date2= new Date("01/01/2014").setHours(0,0,0,0);
Now: if date1.valueOf()> date2.valueOf() will work like a charm.

The simple way is,
var first = '2012-11-21';
var second = '2012-11-03';
if (new Date(first) > new Date(second) {
.....
}

SHORT ANSWER
Here is a function that return {boolean} if the from dateTime > to dateTime Demo in action
var from = '08/19/2013 00:00'
var to = '08/12/2013 00:00 '
function isFromBiggerThanTo(dtmfrom, dtmto){
return new Date(dtmfrom).getTime() >= new Date(dtmto).getTime() ;
}
console.log(isFromBiggerThanTo(from, to)); //true
Explanation
jsFiddle
var date_one = '2013-07-29 01:50:00',
date_two = '2013-07-29 02:50:00';
//getTime() returns the number of milliseconds since 01.01.1970.
var timeStamp_date_one = new Date(date_one).getTime() ; //1375077000000
console.log(typeof timeStamp_date_one);//number
var timeStamp_date_two = new Date(date_two).getTime() ;//1375080600000
console.log(typeof timeStamp_date_two);//number
since you are now having both datetime in number type
you can compare them with any Comparison operations
( >, < ,= ,!= ,== ,!== ,>= AND <=)
Then
if you are familiar with C# Custom Date and Time Format String this library should do the exact same thing and help you format your date and time dtmFRM whether you are passing in date time string or unix format
Usage
var myDateTime = new dtmFRM();
alert(myDateTime.ToString(1375077000000, "MM/dd/yyyy hh:mm:ss ampm"));
//07/29/2013 01:50:00 AM
alert(myDateTime.ToString(1375077000000,"the year is yyyy and the day is dddd"));
//this year is 2013 and the day is Monday
alert(myDateTime.ToString('1/21/2014', "this month is MMMM and the day is dd"));
//this month is january and the day is 21
DEMO
all you have to do is passing any of these format pacified in the library js file

You can use this code:
var firstValue = "2012-05-12".split('-');
var secondValue = "2014-07-12".split('-');
var firstDate=new Date();
firstDate.setFullYear(firstValue[0],(firstValue[1] - 1 ),firstValue[2]);
var secondDate=new Date();
secondDate.setFullYear(secondValue[0],(secondValue[1] - 1 ),secondValue[2]);
if (firstDate > secondDate)
{
alert("First Date is greater than Second Date");
}
else
{
alert("Second Date is greater than First Date");
}
And also check the MDN article for the Date class.

function datesEqual(a, b)
{
return (!(a>b || b>a))
}

var date = new Date(); // will give you todays date.
// following calls, will let you set new dates.
setDate()
setFullYear()
setHours()
setMilliseconds()
setMinutes()
setMonth()
setSeconds()
setTime()
var yesterday = new Date();
yesterday.setDate(...date info here);
if(date>yesterday) // will compare dates

BEWARE THE TIMEZONE
A javascript date has no notion of timezone. It's a moment in time (ticks since the epoch) with handy functions for translating to and from strings in the "local" timezone. If you want to work with dates using date objects, as everyone here is doing, you want your dates to represent UTC midnight at the start of the date in question. This is a common and necessary convention that lets you work with dates regardless of the season or timezone of their creation. So you need to be very vigilant to manage the notion of timezone, particularly when you create your midnight UTC Date object.
Most of the time, you will want your date to reflect the timezone of the user. Click if today is your birthday. Users in NZ and US click at the same time and get different dates. In that case, do this...
// create a date (utc midnight) reflecting the value of myDate and the environment's timezone offset.
new Date(Date.UTC(myDate.getFullYear(),myDate.getMonth(), myDate.getDate()));
Sometimes, international comparability trumps local accuracy. In that case, do this...
// the date in London of a moment in time. Device timezone is ignored.
new Date(Date.UTC(myDate.getUTCYear(), myDate.getyUTCMonth(), myDate.getUTCDate()));
Now you can directly compare your date objects as the other answers suggest.
Having taken care to manage timezone when you create, you also need to be sure to keep timezone out when you convert back to a string representation. So you can safely use...
toISOString()
getUTCxxx()
getTime() //returns a number with no time or timezone.
.toLocaleDateString("fr",{timezone:"UTC"}) // whatever locale you want, but ALWAYS UTC.
And totally avoid everything else, especially...
getYear(),getMonth(),getDate()

Via Moment.js
Jsfiddle: http://jsfiddle.net/guhokemk/1/
function compare(dateTimeA, dateTimeB) {
var momentA = moment(dateTimeA,"DD/MM/YYYY");
var momentB = moment(dateTimeB,"DD/MM/YYYY");
if (momentA > momentB) return 1;
else if (momentA < momentB) return -1;
else return 0;
}
alert(compare("11/07/2015", "10/07/2015"));
The method returns 1 if dateTimeA is greater than dateTimeB
The method returns 0 if dateTimeA equals dateTimeB
The method returns -1 if dateTimeA is less than dateTimeB

Just to add yet another possibility to the many existing options, you could try:
if (date1.valueOf()==date2.valueOf()) .....
...which seems to work for me. Of course you do have to ensure that both dates are not undefined...
if ((date1?date1.valueOf():0)==(date2?date2.valueOf():0) .....
This way we can ensure that a positive comparison is made if both are undefined also, or...
if ((date1?date1.valueOf():0)==(date2?date2.valueOf():-1) .....
...if you prefer them not to be equal.

If following is your date format, you can use this code:
var first = '2012-11-21';
var second = '2012-11-03';
if(parseInt(first.replace(/-/g,""),10) > parseInt(second.replace(/-/g,""),10)){
//...
}
It will check whether 20121121 number is bigger than 20121103 or not.

Subtract two date get the difference in millisecond, if you get 0 it's the same date
function areSameDate(d1, d2){
return d1 - d2 === 0
}

Say you got the date objects A and B, get their EPOC time value, then subtract to get the difference in milliseconds.
var diff = +A - +B;
That's all.

One way to compare two dates is to use the dates.js library.
The Date.compare(Date date1, Date date2) method that returns a number which means the one of following result:
-1 = date1 is less than date2.
0 = values are equal.
1 = date1 is greater than date2.

Performance
Today 2020.02.27 I perform tests of chosen solutions on Chrome v80.0, Safari v13.0.5 and Firefox 73.0.1 on MacOs High Sierra v10.13.6
Conclusions
solutions d1==d2 (D) and d1===d2 (E) are fastest for all browsers
solution getTime (A) is faster than valueOf (B) (both are medium fast)
solutions F,L,N are slowest for all browsers
Details
In below snippet solutions used in performance tests are presented. You can perform test in you machine HERE
function A(d1,d2) {
return d1.getTime() == d2.getTime();
}
function B(d1,d2) {
return d1.valueOf() == d2.valueOf();
}
function C(d1,d2) {
return Number(d1) == Number(d2);
}
function D(d1,d2) {
return d1 == d2;
}
function E(d1,d2) {
return d1 === d2;
}
function F(d1,d2) {
return (!(d1>d2 || d2>d1));
}
function G(d1,d2) {
return d1*1 == d2*1;
}
function H(d1,d2) {
return +d1 == +d2;
}
function I(d1,d2) {
return !(+d1 - +d2);
}
function J(d1,d2) {
return !(d1 - d2);
}
function K(d1,d2) {
return d1 - d2 == 0;
}
function L(d1,d2) {
return !((d1>d2)-(d1<d2));
}
function M(d1,d2) {
return d1.getFullYear() === d2.getFullYear()
&& d1.getDate() === d2.getDate()
&& d1.getMonth() === d2.getMonth();
}
function N(d1,d2) {
return (isFinite(d1.valueOf()) && isFinite(d2.valueOf()) ? !((d1>d2)-(d1<d2)) : false );
}
// TEST
let past= new Date('2002-12-24'); // past
let now= new Date('2020-02-26'); // now
console.log('Code d1>d2 d1<d2 d1=d2')
var log = (l,f) => console.log(`${l} ${f(now,past)} ${f(past,now)} ${f(now,now)}`);
log('A',A);
log('B',B);
log('C',C);
log('D',D);
log('E',E);
log('G',G);
log('H',H);
log('I',I);
log('J',J);
log('K',K);
log('L',L);
log('M',M);
log('N',N);
p {color: red}
<p>This snippet only presents tested solutions (it not perform tests itself)</p>
Results for chrome

In order to create dates from free text in JavaScript you need to parse it into the Date object.
You could use Date.parse() which takes free text and tries to convert it into a new date but if you have control over the page I would recommend using HTML select boxes instead or a date picker such as the YUI calendar control or the jQuery UI Datepicker.
Once you have a date, as other people have pointed out, you can use simple arithmetic to subtract the dates and convert it back into a number of days by dividing the number (in seconds) by the number of seconds in a day (60*60*24 = 86400).

var date_today=new Date();
var formated_date = formatDate(date_today);//Calling formatDate Function
var input_date="2015/04/22 11:12 AM";
var currentDateTime = new Date(Date.parse(formated_date));
var inputDateTime = new Date(Date.parse(input_date));
if (inputDateTime <= currentDateTime){
//Do something...
}
function formatDate(date) {
var hours = date.getHours();
var minutes = date.getMinutes();
var ampm = hours >= 12 ? 'PM' : 'AM';
hours = hours % 12;
hours = hours ? hours : 12; // the hour '0' should be '12'
hours = hours < 10 ? '0'+hours : hours ;
minutes = minutes < 10 ? '0'+minutes : minutes;
var strTime = hours+":"+minutes+ ' ' + ampm;
return date.getFullYear()+ "/" + ((date.getMonth()+1) < 10 ? "0"+(date.getMonth()+1) :
(date.getMonth()+1) ) + "/" + (date.getDate() < 10 ? "0"+date.getDate() :
date.getDate()) + " " + strTime;
}

An Improved version of the code posted by "some"
/* Compare the current date against another date.
*
* #param b {Date} the other date
* #returns -1 : if this < b
* 0 : if this === b
* 1 : if this > b
* NaN : if a or b is an illegal date
*/
Date.prototype.compare = function(b) {
if (b.constructor !== Date) {
throw "invalid_date";
}
return (isFinite(this.valueOf()) && isFinite(b.valueOf()) ?
(this>b)-(this<b) : NaN
);
};
usage:
var a = new Date(2011, 1-1, 1);
var b = new Date(2011, 1-1, 1);
var c = new Date(2011, 1-1, 31);
var d = new Date(2011, 1-1, 31);
assertEquals( 0, a.compare(b));
assertEquals( 0, b.compare(a));
assertEquals(-1, a.compare(c));
assertEquals( 1, c.compare(a));

I usually store Dates as timestamps(Number) in databases.
When I need to compare, I simply compare among those timestamps or
convert it to Date Object and then compare with > <if necessary.
Note that == or === does not work properly unless your variables are references of the same Date Object.
Convert those Date objects to timestamp(number) first and then compare equality of them.
Date to Timestamp
var timestamp_1970 = new Date(0).getTime(); // 1970-01-01 00:00:00
var timestamp = new Date().getTime(); // Current Timestamp
Timestamp to Date
var timestamp = 0; // 1970-01-01 00:00:00
var DateObject = new Date(timestamp);

Before comparing the Dates object, try setting both of their milliseconds to zero like Date.setMilliseconds(0);.
In some cases where the Date object is dynamically created in javascript, if you keep printing the Date.getTime(), you'll see the milliseconds changing, which will prevent the equality of both dates.

Let's suppose that you deal with this 2014[:-/.]06[:-/.]06 or this 06[:-/.]06[:-/.]2014 date format, then you may compare dates this way
var a = '2014.06/07', b = '2014-06.07', c = '07-06/2014', d = '07/06.2014';
parseInt(a.replace(/[:\s\/\.-]/g, '')) == parseInt(b.replace(/[:\s\/\.-]/g, '')); // true
parseInt(c.replace(/[:\s\/\.-]/g, '')) == parseInt(d.replace(/[:\s\/\.-]/g, '')); // true
parseInt(a.replace(/[:\s\/\.-]/g, '')) < parseInt(b.replace(/[:\s\/\.-]/g, '')); // false
parseInt(c.replace(/[:\s\/\.-]/g, '')) > parseInt(d.replace(/[:\s\/\.-]/g, '')); // false
As you can see, we strip separator(s) and then compare integers.

My simple answer for this question
checkDisabled(date) {
const today = new Date()
const newDate = new Date(date._d)
if (today.getTime() > newDate.getTime()) {
return true
}
return false
}

If both of your dates come in the format "YYYY-MM-DD", you can skip the Date object and compare strings directly.
This works because of how the strings are compared in JS
let date1 = '2022-12-13';
let date2 = '2022-02-13';
console.log(`${date1} > ${date2}`, date1 > date2);
console.log(`${date1} < ${date2}`, date1 < date2);
console.log(`${date1} == ${date2}`, date1 == date2);

Comparing different date formats [duplicate]

Can someone suggest a way to compare the values of two dates greater than, less than, and not in the past using JavaScript? The values will be coming from text boxes.

The Date object will do what you want - construct one for each date, then compare them using the >, <, <= or >=.
The ==, !=, ===, and !== operators require you to use date.getTime() as in
var d1 = new Date();
var d2 = new Date(d1);
var same = d1.getTime() === d2.getTime();
var notSame = d1.getTime() !== d2.getTime();
to be clear just checking for equality directly with the date objects won't work
var d1 = new Date();
var d2 = new Date(d1);
console.log(d1 == d2); // prints false (wrong!)
console.log(d1 === d2); // prints false (wrong!)
console.log(d1 != d2); // prints true (wrong!)
console.log(d1 !== d2); // prints true (wrong!)
console.log(d1.getTime() === d2.getTime()); // prints true (correct)
I suggest you use drop-downs or some similar constrained form of date entry rather than text boxes, though, lest you find yourself in input validation hell.
For the curious, date.getTime() documentation:
Returns the numeric value of the specified date as the number of milliseconds since January 1, 1970, 00:00:00 UTC. (Negative values are returned for prior times.)

Compare < and > just as usual, but anything involving == or === should use a + prefix. Like so:
const x = new Date('2013-05-23');
const y = new Date('2013-05-23');
// less than, greater than is fine:
console.log('x < y', x < y); // false
console.log('x > y', x > y); // false
console.log('x <= y', x <= y); // true
console.log('x >= y', x >= y); // true
console.log('x === y', x === y); // false, oops!
// anything involving '==' or '===' should use the '+' prefix
// it will then compare the dates' millisecond values
console.log('+x === +y', +x === +y); // true

The easiest way to compare dates in javascript is to first convert it to a Date object and then compare these date-objects.
Below you find an object with three functions:
dates.compare(a,b)
Returns a number:
-1 if a < b
0 if a = b
1 if a > b
NaN if a or b is an illegal date
dates.inRange (d,start,end)
Returns a boolean or NaN:
true if d is between the start and end (inclusive)
false if d is before start or after end.
NaN if one or more of the dates are illegal.
dates.convert
Used by the other functions to convert their input to a date object. The input can be
a date-object : The input is returned as is.
an array: Interpreted as [year,month,day]. NOTE month is 0-11.
a number : Interpreted as number of milliseconds since 1 Jan 1970 (a timestamp)
a string : Several different formats is supported, like "YYYY/MM/DD", "MM/DD/YYYY", "Jan 31 2009" etc.
an object: Interpreted as an object with year, month and date attributes. NOTE month is 0-11.
.
// Source: http://stackoverflow.com/questions/497790
var dates = {
convert:function(d) {
// Converts the date in d to a date-object. The input can be:
// a date object: returned without modification
// an array : Interpreted as [year,month,day]. NOTE: month is 0-11.
// a number : Interpreted as number of milliseconds
// since 1 Jan 1970 (a timestamp)
// a string : Any format supported by the javascript engine, like
// "YYYY/MM/DD", "MM/DD/YYYY", "Jan 31 2009" etc.
// an object : Interpreted as an object with year, month and date
// attributes. **NOTE** month is 0-11.
return (
d.constructor === Date ? d :
d.constructor === Array ? new Date(d[0],d[1],d[2]) :
d.constructor === Number ? new Date(d) :
d.constructor === String ? new Date(d) :
typeof d === "object" ? new Date(d.year,d.month,d.date) :
NaN
);
},
compare:function(a,b) {
// Compare two dates (could be of any type supported by the convert
// function above) and returns:
// -1 : if a < b
// 0 : if a = b
// 1 : if a > b
// NaN : if a or b is an illegal date
// NOTE: The code inside isFinite does an assignment (=).
return (
isFinite(a=this.convert(a).valueOf()) &&
isFinite(b=this.convert(b).valueOf()) ?
(a>b)-(a<b) :
NaN
);
},
inRange:function(d,start,end) {
// Checks if date in d is between dates in start and end.
// Returns a boolean or NaN:
// true : if d is between start and end (inclusive)
// false : if d is before start or after end
// NaN : if one or more of the dates is illegal.
// NOTE: The code inside isFinite does an assignment (=).
return (
isFinite(d=this.convert(d).valueOf()) &&
isFinite(start=this.convert(start).valueOf()) &&
isFinite(end=this.convert(end).valueOf()) ?
start <= d && d <= end :
NaN
);
}
}

The relational operators < <= > >= can be used to compare JavaScript dates:
var d1 = new Date(2013, 0, 1);
var d2 = new Date(2013, 0, 2);
d1 < d2; // true
d1 <= d2; // true
d1 > d2; // false
d1 >= d2; // false
However, the equality operators == != === !== cannot be used to compare (the value of) dates because:
Two distinct objects are never equal for either strict or abstract comparisons.
An expression comparing Objects is only true if the operands reference the same Object.
You can compare the value of dates for equality using any of these methods:
var d1 = new Date(2013, 0, 1);
var d2 = new Date(2013, 0, 1);
/*
* note: d1 == d2 returns false as described above
*/
d1.getTime() == d2.getTime(); // true
d1.valueOf() == d2.valueOf(); // true
Number(d1) == Number(d2); // true
+d1 == +d2; // true
Both Date.getTime() and Date.valueOf() return the number of milliseconds since January 1, 1970, 00:00 UTC. Both Number function and unary + operator call the valueOf() methods behind the scenes.

By far the easiest method is to subtract one date from the other and compare the result.
var oDateOne = new Date();
var oDateTwo = new Date();
alert(oDateOne - oDateTwo === 0);
alert(oDateOne - oDateTwo < 0);
alert(oDateOne - oDateTwo > 0);

Comparing dates in JavaScript is quite easy... JavaScript has built-in comparison system for dates which makes it so easy to do the comparison...
Just follow these steps for comparing 2 dates value, for example you have 2 inputs which each has a Date value in String and you to compare them...
1. you have 2 string values you get from an input and you'd like to compare them, they are as below:
var date1 = '01/12/2018';
var date2 = '12/12/2018';
2. They need to be Date Object to be compared as date values, so simply convert them to date, using new Date(), I just re-assign them for simplicity of explanation, but you can do it anyway you like:
date1 = new Date(date1);
date2 = new Date(date2);
3. Now simply compare them, using the > < >= <=
date1 > date2; //false
date1 < date2; //true
date1 >= date2; //false
date1 <= date2; //true

Compare day only (ignoring time component):
Date.prototype.sameDay = function(d) {
return this.getFullYear() === d.getFullYear()
&& this.getDate() === d.getDate()
&& this.getMonth() === d.getMonth();
}
Usage:
if(date1.sameDay(date2)) {
// highlight day on calendar or something else clever
}
I no longer recommend modifying the prototype of built-in objects. Try this instead:
function isSameDay(d1, d2) {
return d1.getFullYear() === d2.getFullYear() &&
d1.getDate() === d2.getDate() &&
d1.getMonth() === d2.getMonth();
}
console.log(isSameDay(new Date('Jan 15 2021 02:39:53 GMT-0800'), new Date('Jan 15 2021 23:39:53 GMT-0800')));
console.log(isSameDay(new Date('Jan 15 2021 10:39:53 GMT-0800'), new Date('Jan 16 2021 10:39:53 GMT-0800')));
N.B. the year/month/day will be returned for your timezone; I recommend using a timezone-aware library if you want to check if two dates are on the same day in a different timezone.
e.g.
> (new Date('Jan 15 2021 01:39:53 Z')).getDate() // Jan 15 in UTC
14 // Returns "14" because I'm in GMT-08

what format?
If you construct a Javascript Date object, you can just subtract them to get a milliseconds difference (edit: or just compare them) :
js>t1 = new Date()
Thu Jan 29 2009 14:19:28 GMT-0500 (Eastern Standard Time)
js>t2 = new Date()
Thu Jan 29 2009 14:19:31 GMT-0500 (Eastern Standard Time)
js>t2-t1
2672
js>t3 = new Date('2009 Jan 1')
Thu Jan 01 2009 00:00:00 GMT-0500 (Eastern Standard Time)
js>t1-t3
2470768442
js>t1>t3
true

Note - Compare Only Date Part:
When we compare two date in javascript. It takes hours, minutes and seconds also into consideration.. So If we only need to compare date only, this is the approach:
var date1= new Date("01/01/2014").setHours(0,0,0,0);
var date2= new Date("01/01/2014").setHours(0,0,0,0);
Now: if date1.valueOf()> date2.valueOf() will work like a charm.

The simple way is,
var first = '2012-11-21';
var second = '2012-11-03';
if (new Date(first) > new Date(second) {
.....
}

SHORT ANSWER
Here is a function that return {boolean} if the from dateTime > to dateTime Demo in action
var from = '08/19/2013 00:00'
var to = '08/12/2013 00:00 '
function isFromBiggerThanTo(dtmfrom, dtmto){
return new Date(dtmfrom).getTime() >= new Date(dtmto).getTime() ;
}
console.log(isFromBiggerThanTo(from, to)); //true
Explanation
jsFiddle
var date_one = '2013-07-29 01:50:00',
date_two = '2013-07-29 02:50:00';
//getTime() returns the number of milliseconds since 01.01.1970.
var timeStamp_date_one = new Date(date_one).getTime() ; //1375077000000
console.log(typeof timeStamp_date_one);//number
var timeStamp_date_two = new Date(date_two).getTime() ;//1375080600000
console.log(typeof timeStamp_date_two);//number
since you are now having both datetime in number type
you can compare them with any Comparison operations
( >, < ,= ,!= ,== ,!== ,>= AND <=)
Then
if you are familiar with C# Custom Date and Time Format String this library should do the exact same thing and help you format your date and time dtmFRM whether you are passing in date time string or unix format
Usage
var myDateTime = new dtmFRM();
alert(myDateTime.ToString(1375077000000, "MM/dd/yyyy hh:mm:ss ampm"));
//07/29/2013 01:50:00 AM
alert(myDateTime.ToString(1375077000000,"the year is yyyy and the day is dddd"));
//this year is 2013 and the day is Monday
alert(myDateTime.ToString('1/21/2014', "this month is MMMM and the day is dd"));
//this month is january and the day is 21
DEMO
all you have to do is passing any of these format pacified in the library js file

You can use this code:
var firstValue = "2012-05-12".split('-');
var secondValue = "2014-07-12".split('-');
var firstDate=new Date();
firstDate.setFullYear(firstValue[0],(firstValue[1] - 1 ),firstValue[2]);
var secondDate=new Date();
secondDate.setFullYear(secondValue[0],(secondValue[1] - 1 ),secondValue[2]);
if (firstDate > secondDate)
{
alert("First Date is greater than Second Date");
}
else
{
alert("Second Date is greater than First Date");
}
And also check the MDN article for the Date class.

function datesEqual(a, b)
{
return (!(a>b || b>a))
}

var date = new Date(); // will give you todays date.
// following calls, will let you set new dates.
setDate()
setFullYear()
setHours()
setMilliseconds()
setMinutes()
setMonth()
setSeconds()
setTime()
var yesterday = new Date();
yesterday.setDate(...date info here);
if(date>yesterday) // will compare dates

BEWARE THE TIMEZONE
A javascript date has no notion of timezone. It's a moment in time (ticks since the epoch) with handy functions for translating to and from strings in the "local" timezone. If you want to work with dates using date objects, as everyone here is doing, you want your dates to represent UTC midnight at the start of the date in question. This is a common and necessary convention that lets you work with dates regardless of the season or timezone of their creation. So you need to be very vigilant to manage the notion of timezone, particularly when you create your midnight UTC Date object.
Most of the time, you will want your date to reflect the timezone of the user. Click if today is your birthday. Users in NZ and US click at the same time and get different dates. In that case, do this...
// create a date (utc midnight) reflecting the value of myDate and the environment's timezone offset.
new Date(Date.UTC(myDate.getFullYear(),myDate.getMonth(), myDate.getDate()));
Sometimes, international comparability trumps local accuracy. In that case, do this...
// the date in London of a moment in time. Device timezone is ignored.
new Date(Date.UTC(myDate.getUTCYear(), myDate.getyUTCMonth(), myDate.getUTCDate()));
Now you can directly compare your date objects as the other answers suggest.
Having taken care to manage timezone when you create, you also need to be sure to keep timezone out when you convert back to a string representation. So you can safely use...
toISOString()
getUTCxxx()
getTime() //returns a number with no time or timezone.
.toLocaleDateString("fr",{timezone:"UTC"}) // whatever locale you want, but ALWAYS UTC.
And totally avoid everything else, especially...
getYear(),getMonth(),getDate()

Via Moment.js
Jsfiddle: http://jsfiddle.net/guhokemk/1/
function compare(dateTimeA, dateTimeB) {
var momentA = moment(dateTimeA,"DD/MM/YYYY");
var momentB = moment(dateTimeB,"DD/MM/YYYY");
if (momentA > momentB) return 1;
else if (momentA < momentB) return -1;
else return 0;
}
alert(compare("11/07/2015", "10/07/2015"));
The method returns 1 if dateTimeA is greater than dateTimeB
The method returns 0 if dateTimeA equals dateTimeB
The method returns -1 if dateTimeA is less than dateTimeB

Just to add yet another possibility to the many existing options, you could try:
if (date1.valueOf()==date2.valueOf()) .....
...which seems to work for me. Of course you do have to ensure that both dates are not undefined...
if ((date1?date1.valueOf():0)==(date2?date2.valueOf():0) .....
This way we can ensure that a positive comparison is made if both are undefined also, or...
if ((date1?date1.valueOf():0)==(date2?date2.valueOf():-1) .....
...if you prefer them not to be equal.

If following is your date format, you can use this code:
var first = '2012-11-21';
var second = '2012-11-03';
if(parseInt(first.replace(/-/g,""),10) > parseInt(second.replace(/-/g,""),10)){
//...
}
It will check whether 20121121 number is bigger than 20121103 or not.

Subtract two date get the difference in millisecond, if you get 0 it's the same date
function areSameDate(d1, d2){
return d1 - d2 === 0
}

Say you got the date objects A and B, get their EPOC time value, then subtract to get the difference in milliseconds.
var diff = +A - +B;
That's all.

One way to compare two dates is to use the dates.js library.
The Date.compare(Date date1, Date date2) method that returns a number which means the one of following result:
-1 = date1 is less than date2.
0 = values are equal.
1 = date1 is greater than date2.

Performance
Today 2020.02.27 I perform tests of chosen solutions on Chrome v80.0, Safari v13.0.5 and Firefox 73.0.1 on MacOs High Sierra v10.13.6
Conclusions
solutions d1==d2 (D) and d1===d2 (E) are fastest for all browsers
solution getTime (A) is faster than valueOf (B) (both are medium fast)
solutions F,L,N are slowest for all browsers
Details
In below snippet solutions used in performance tests are presented. You can perform test in you machine HERE
function A(d1,d2) {
return d1.getTime() == d2.getTime();
}
function B(d1,d2) {
return d1.valueOf() == d2.valueOf();
}
function C(d1,d2) {
return Number(d1) == Number(d2);
}
function D(d1,d2) {
return d1 == d2;
}
function E(d1,d2) {
return d1 === d2;
}
function F(d1,d2) {
return (!(d1>d2 || d2>d1));
}
function G(d1,d2) {
return d1*1 == d2*1;
}
function H(d1,d2) {
return +d1 == +d2;
}
function I(d1,d2) {
return !(+d1 - +d2);
}
function J(d1,d2) {
return !(d1 - d2);
}
function K(d1,d2) {
return d1 - d2 == 0;
}
function L(d1,d2) {
return !((d1>d2)-(d1<d2));
}
function M(d1,d2) {
return d1.getFullYear() === d2.getFullYear()
&& d1.getDate() === d2.getDate()
&& d1.getMonth() === d2.getMonth();
}
function N(d1,d2) {
return (isFinite(d1.valueOf()) && isFinite(d2.valueOf()) ? !((d1>d2)-(d1<d2)) : false );
}
// TEST
let past= new Date('2002-12-24'); // past
let now= new Date('2020-02-26'); // now
console.log('Code d1>d2 d1<d2 d1=d2')
var log = (l,f) => console.log(`${l} ${f(now,past)} ${f(past,now)} ${f(now,now)}`);
log('A',A);
log('B',B);
log('C',C);
log('D',D);
log('E',E);
log('G',G);
log('H',H);
log('I',I);
log('J',J);
log('K',K);
log('L',L);
log('M',M);
log('N',N);
p {color: red}
<p>This snippet only presents tested solutions (it not perform tests itself)</p>
Results for chrome

In order to create dates from free text in JavaScript you need to parse it into the Date object.
You could use Date.parse() which takes free text and tries to convert it into a new date but if you have control over the page I would recommend using HTML select boxes instead or a date picker such as the YUI calendar control or the jQuery UI Datepicker.
Once you have a date, as other people have pointed out, you can use simple arithmetic to subtract the dates and convert it back into a number of days by dividing the number (in seconds) by the number of seconds in a day (60*60*24 = 86400).

var date_today=new Date();
var formated_date = formatDate(date_today);//Calling formatDate Function
var input_date="2015/04/22 11:12 AM";
var currentDateTime = new Date(Date.parse(formated_date));
var inputDateTime = new Date(Date.parse(input_date));
if (inputDateTime <= currentDateTime){
//Do something...
}
function formatDate(date) {
var hours = date.getHours();
var minutes = date.getMinutes();
var ampm = hours >= 12 ? 'PM' : 'AM';
hours = hours % 12;
hours = hours ? hours : 12; // the hour '0' should be '12'
hours = hours < 10 ? '0'+hours : hours ;
minutes = minutes < 10 ? '0'+minutes : minutes;
var strTime = hours+":"+minutes+ ' ' + ampm;
return date.getFullYear()+ "/" + ((date.getMonth()+1) < 10 ? "0"+(date.getMonth()+1) :
(date.getMonth()+1) ) + "/" + (date.getDate() < 10 ? "0"+date.getDate() :
date.getDate()) + " " + strTime;
}

An Improved version of the code posted by "some"
/* Compare the current date against another date.
*
* #param b {Date} the other date
* #returns -1 : if this < b
* 0 : if this === b
* 1 : if this > b
* NaN : if a or b is an illegal date
*/
Date.prototype.compare = function(b) {
if (b.constructor !== Date) {
throw "invalid_date";
}
return (isFinite(this.valueOf()) && isFinite(b.valueOf()) ?
(this>b)-(this<b) : NaN
);
};
usage:
var a = new Date(2011, 1-1, 1);
var b = new Date(2011, 1-1, 1);
var c = new Date(2011, 1-1, 31);
var d = new Date(2011, 1-1, 31);
assertEquals( 0, a.compare(b));
assertEquals( 0, b.compare(a));
assertEquals(-1, a.compare(c));
assertEquals( 1, c.compare(a));

I usually store Dates as timestamps(Number) in databases.
When I need to compare, I simply compare among those timestamps or
convert it to Date Object and then compare with > <if necessary.
Note that == or === does not work properly unless your variables are references of the same Date Object.
Convert those Date objects to timestamp(number) first and then compare equality of them.
Date to Timestamp
var timestamp_1970 = new Date(0).getTime(); // 1970-01-01 00:00:00
var timestamp = new Date().getTime(); // Current Timestamp
Timestamp to Date
var timestamp = 0; // 1970-01-01 00:00:00
var DateObject = new Date(timestamp);

Before comparing the Dates object, try setting both of their milliseconds to zero like Date.setMilliseconds(0);.
In some cases where the Date object is dynamically created in javascript, if you keep printing the Date.getTime(), you'll see the milliseconds changing, which will prevent the equality of both dates.

Let's suppose that you deal with this 2014[:-/.]06[:-/.]06 or this 06[:-/.]06[:-/.]2014 date format, then you may compare dates this way
var a = '2014.06/07', b = '2014-06.07', c = '07-06/2014', d = '07/06.2014';
parseInt(a.replace(/[:\s\/\.-]/g, '')) == parseInt(b.replace(/[:\s\/\.-]/g, '')); // true
parseInt(c.replace(/[:\s\/\.-]/g, '')) == parseInt(d.replace(/[:\s\/\.-]/g, '')); // true
parseInt(a.replace(/[:\s\/\.-]/g, '')) < parseInt(b.replace(/[:\s\/\.-]/g, '')); // false
parseInt(c.replace(/[:\s\/\.-]/g, '')) > parseInt(d.replace(/[:\s\/\.-]/g, '')); // false
As you can see, we strip separator(s) and then compare integers.

My simple answer for this question
checkDisabled(date) {
const today = new Date()
const newDate = new Date(date._d)
if (today.getTime() > newDate.getTime()) {
return true
}
return false
}

If both of your dates come in the format "YYYY-MM-DD", you can skip the Date object and compare strings directly.
This works because of how the strings are compared in JS
let date1 = '2022-12-13';
let date2 = '2022-02-13';
console.log(`${date1} > ${date2}`, date1 > date2);
console.log(`${date1} < ${date2}`, date1 < date2);
console.log(`${date1} == ${date2}`, date1 == date2);

how compare two dates with moment.js

I have three different types of dates and I can not compare them.
let withOneDayLess = moment().subtract(1, "days").format("DD-MM-YYYY");
//let justnow = moment().format("DD-MM-YYYY");
let takenAt = moment.unix(story.takenAt).format("DD-MM-YYYY");
if(takenAt >= withOneDayLess){
Arrstory.push(story)
console.log(takenAt," - " ,withOneDayLess)
};
story.takenAt is the date of a story in unix, and I need all the stories between yesterday and today, but I think the if compares only the first number, giving me stories that do not correspond

I'm assuming your currentDate variable is also created as a .format("DD-MM-YYYY") method call... so you're not comparing dates - you're comparing strings. Compare the dates to get your desired result:
var d1 = moment().subtract(1,"days");
var d2 = moment();
if (d1 < d2) alert(d1);
let currentDate = moment();
let story = { takenAt: 1746713004 };
let withOneDayLess = moment().subtract(1, "days").format("DD-MM-YYYY");
let justnow = moment().format("DD-MM-YYYY");
let takenAt = moment.unix(story.takenAt).format("DD-MM-YYYY");
// this will never alert - typeof(takenAt) === "string" and the comparison
// "08-05-2025" is not >= "Sat Jan 05 2019 10:36:11 GMT-0800" as currentDate
// get coerced to a string to do the comparison if it's not a string already.
if(takenAt >= currentDate){
alert("takenAt is later than currentDate");
}
// this WILL work because it's comparing a moment date to a moment date directly.
takenAt = moment.unix(story.takenAt);
if(takenAt >= currentDate){
alert(takenAt.format("DD-MM-YYYY") + " is later than " + currentDate.format("DD-MM-YYYY"));
}

Change particles if is winter in javascript

I have two configurations (json) for particles js. One of them is for winter time, so it should be active from 21. December to 21. March. I tried many things, and still not working (Not because is still November :) )
Last thing I tried is this
var today = new Date();
var tDate = today.getDate();
var tMonth = today.getMonth();
var startingDate = new Date();
var sDate = startingDate.setDate(1);
var sMonth = startingDate.setMonth(10);
var endingDate = new Date();
var eDate = endingDate.setDate(21);
var eMonth = endingDate.setMonth(2);
if (tMonth >= sMonth && tMonth <= eMonth) {
if (tDate >= sDate && tDate <= eDate) {
particlesJS.load('particles', '../../Content/Scripts/particles/particles-config-winter.json');
}
}
else {
particlesJS.load('particles', '../../Content/Scripts/particles/particles-config.json');
}
This does not make sense, because starting and ending date is both 21. I tried to compare as string, didn't work out. I have no ideas how to compare two dates in javascript. Any help?

You could use this function:
function isWinter(dt) {
const m = dt.getMonth();
return m == 11 ? dt.getDate() >= 21 : m == 2 ? dt.getDate() < 21 : m < 2;
}
Call it for today's date like this:
if (isWinter(new Date())) { /*....*/ }
One of the issues in your attempt is that setMonth and setDate methods return the modified date as number of milliseconds (not just a month or day part) and mutate the date on which the method is called.
Explanation of the function:
The ternary expression uses this logic:
If the month is December (11), then return true when the day-of-the-month is at least 21 or false otherwise: this is what dt.getDate() >= 21 evaluates to (true or false).
Otherwise, if the month is March (2), then return true when the day-of-the-month is less than 21 or false otherwise: same principle as above, but reversed
Otherwise, return true when the month comes before March ( < 2 ) and false otherwise: this is what m < 2 evaluates to.

Date manipulation is always a struggle. If you don't mind libraries to handle this for you, i would suggest you to look at MomentJs which makes it easy to manipulate date and time. However each library you add, you add unnecessary code which you might not need. Therefore if you only need do a few date manipulations, it might not be worth it and trincot's's answer is perfect, if you don't really need MomentJs.
Following the line of trincot's answer, this is how you do the same thing in MomentJs:
function isWinter(date){
date.year(moment().year()); //Normalize year.
let winterStart = moment('21-12', 'DD-MM');
let winterEnd = moment('21-03', 'DD-MM');
return !date.isBetween(winterEnd, winterStart, 'day')
}
//Tests:
let today = moment('20-12', 'DD-MM');
alert(isWinter(today)); //false
today = moment('21-12', 'DD-MM');
alert(isWinter(today)); //true
today = moment('21-03', 'DD-MM');
alert(isWinter(today)); //true
today = moment('22-03', 'DD-MM');
alert(isWinter(today)); //false
today = moment('22-03-2019', 'DD-MM-YYYY');
alert(isWinter(today)); //false
today = moment('21-03-2019', 'DD-MM-YYYY');
alert(isWinter(today)); //true
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.22.2/moment.min.js"></script>

To explain why your code doesn't work:
var today = new Date();
var tDate = today.getDate();
var tMonth = today.getMonth();
var startingDate = new Date();
// This sets the date to the first of the month, and sets sDate to a number
// that is the time value of the adjusted date
var sDate = startingDate.setDate(1);
// This sets the month to November and sMonth to the adjusted time value
var sMonth = startingDate.setMonth(10);
var endingDate = new Date();
// As above, this sets endingDate to 21 March and sets eDate and eMonth to numbers
var eDate = endingDate.setDate(21);
var eMonth = endingDate.setMonth(2);
// This will never be true after 1970-01-01 as you're comparing a months to a time values
if (tMonth >= sMonth && tMonth <= eMonth) {
if (tDate >= sDate && tDate <= eDate) {
Even if this used correct values, the logic doesn't work as even for a date in the range, you're then comparing the date (day number) when that should only be compared if the month is March or November, not any other month (per Trincot's answer).
It's easier if you create dates for 21 March and 21 December in the current year, then see if the current date falls in the range. If it does, it's not winter. If it doesn't, it's winter. I've assumed that the range is inclusive, adjust the dates if that isn't the case.
function isWinter(date = new Date()) {
var start = new Date(date.getFullYear(), 2, 21);
var end = new Date(date.getFullYear(), 11, 21);
return date > start && date < end;
}
[new Date(2018, 0, 1), // 1 Jan 2018, winter
new Date(2018, 2,21), // 21 Mar 2018, winter
new Date(2018, 5, 1), // 1 Jun 2018, not winter
new Date(2018,11,21), // 21 Dec 2018, winter
new Date() // Today ...
].forEach(d => console.log(`${d} is ${isWinter(d)?'not ':''}winter`));

javascript date validation not validation February 31

I am trying to write some code with will validate form data. I have a date field which should have a mm/dd/yyyy format. I needed to catch exceptions such as February 31, so I added this code:
var d = new Date(dob);
if (isNaN(d.getTime())) { //this if is to take care of February 31, BUT IT DOESN'T!
error = 1;
message += "<li>Invalid Date</li>";
} else {
var date_regex = /^(0[1-9]|1[0-2])\/(0[1-9]|1\d|2\d|3[01])\/(19|20)\d{2}$/;
var validFormat = date_regex.test(dob);
if (!(validFormat)) {
error = 1;
message += "<li>Invalid date format - date must have format mm/dd/yyyy</li>";
}
}
However I found something very weird: while the date 02/32/2000 errors as an invalid date, 02/31/2000 does not!

Due to what I said in the comments...
Another way you could check if a date is valid is by checking whether or not the stuff you passed into the new Date function is the same as what comes out of it, like this:
// Remember that the month is 0-based so February is actually 1...
function isValidDate(year, month, day) {
var d = new Date(year, month, day);
if (d.getFullYear() == year && d.getMonth() == month && d.getDate() == day) {
return true;
}
return false;
}
then you could do this:
if (isValidDate(2013,1,31))
and it would return true if valid and false if invalid.

After wrecking my head with the obscurity of Date .getMonth() (and also weekday by .getDay()) being 0-index (despite year, day and all the others not being like so... oh god...) I've re-wrote Jeff's answer to make it more readable and more friendly-usable to whom consume the method from outside.
ES6 code
You can call passing month as 1-indexed as you'd normally expect.
I've parsed inputs using Number constructor so I can use strict equality to more confidently compare values.
I'm using the UTC version methods to avoid having to deal with the local timezone.
Also, I broke steps down into some variables for the sake of readability.
/**
*
* #param { number | string } day
* #param { number | string } month
* #param { number| string } year
* #returns { boolean }
*/
function validateDateString(day, month, year) {
day = Number(day);
month = Number(month) - 1; //bloody 0-indexed month
year = Number(year);
let d = new Date(year, month, day);
let yearMatches = d.getUTCFullYear() === year;
let monthMatches = d.getUTCMonth() === month;
let dayMatches = d.getUTCDate() === day;
return yearMatches && monthMatches && dayMatches;
}

Are you able to use a library?
My first port of call for date handling in Javascript is moment.js: "A javascript date library for parsing, validating, manipulating, and formatting dates."

The ususal way to validate a 'mm/dd/yyyy' date string is to create a date object and verify that its month and date are the same as the input.
function isvalid_mdy(s){
var day, A= s.match(/[1-9][\d]*/g);
try{
A[0]-= 1;
day= new Date(+A[2], A[0], +A[1]);
if(day.getMonth()== A[0] && day.getDate()== A[1]) return day;
throw new Error('Bad Date ');
}
catch(er){
return er.message;
}
}
isvalid_mdy('02/31/2000')
/* returned value: (Error)Bad Date */

Assuming month input is 1-12 (1-based, not 0-based):
function isValidDate(year, month, day) {
var d = new Date(year, month - 1, day);
return month == d.getMonth() + 1;
}
isValidDate(2019, 12, 0); //=> false
isValidDate(2020, 2, 29); //=> true
isValidDate(2021, 2, 29); //=> false
isValidDate(2022, 2, 31); //=> false

Basically an alternative to the above-mentioned examples
function (date) {
if (!/(0[1-9]|1[0-9]|2[0-9]|3[0-1])\/(0[1-9]|1[0-2])\/([1-2][0-9]{3})/g.test(date))
{
alert('Incorrect date format please follow this form: dd/mm/yyyy');
return;
}
else
{
// secondary validation
const parts = (date).split('/').map((p) => parseInt(p, 10));
let day = Number(parts[0]);
let month = Number(parts[1]) - 1; // 0-indexed month
let year = Number(parts[2]);
let d = new Date(year, month, day);
if (!(d.getFullYear() == year && d.getMonth() == month && d.getDate() == day))
{
alert('Incorrect date, please enter the correct day entry');
return;
}
}
}

I may be a little late for posting an answer but here is what worked best for me
var user_date = (`${user_values.month_value} ${user_values.date_value} , ${user_values.year_value}`)
const d = new Date(user_date);
let day = d.getDate()
if(user_values.date_value != day){
setdate_validation({
display:'flex'
})
}
else{
setdate_validation({
display:'none'
})
console.log(user_values)
so in the above code what happens is i get different inputs from my user like one dropdown for date another for month and so on , i collect them and store it with .getdate() now .getdate() function returns the value of day , so if i stored (02 21 , 2002) then the .getdate() will return 21 ,
but there is a catch if i enter an invalid date like (02 30, 2002) where 30 is invalid in month of february then the .getdate() function returns not the same date but the date in next month or increment as much you are far away from a valid date like if 28 is valid and I entered 29 then .getdate() will show 1 as the output so i just compare the result of .getdate() with my current date value which is entered and if it is not same then the date is invalid.
(this code is from react using usestates)