Determining Date Equality in Javascript

Question

I need to find out if two dates the user selects are the same in Javascript. The dates are passed to this function in a String ("xx/xx/xxxx").That is all the granularity I need.

Here is my code:

        var valid = true;
    var d1 = new Date($('#datein').val());
    var d2 = new Date($('#dateout').val());
    alert(d1+"\n"+d2);
    if(d1 > d2) {
        alert("Your check out date must be after your check in date.");
        valid = false;
    } else if(d1 == d2) {
        alert("You cannot check out on the same day you check in.");
        valid = false;
    }

The javascript alert after converting the dates to objects looks like this:

Tue Jan 25 2011 00:00:00 GMT-0800 (Pacific Standard Time)

The test to determine if date 1 is greater than date 2 works. But using the == or === operators do not change valid to false.

Have you checked this post out: http://stackoverflow.com/questions/338463/how-do-i-do-a-date-comparison-in-javascript. Does it help? — JohnMerlino, Jan 03 '11 at 18:21
Tempted to flag this as a duplicate but I think this is a fringe case of the same issue, so I'm not. — Liam, Nov 20 '13 at 10:52
This is not a duplicate. The post mentionned (and the accepted answer) are about determining if a date is before or after another, not about equality. — yannick1976, Jul 23 '15 at 17:49

score 178 · Accepted Answer · edited Apr 22 '18 at 07:20

178

Use the getTime() method. It will check the numeric value of the date and it will work for both the greater than/less than checks as well as the equals checks.

EDIT:

if (d1.getTime() === d2.getTime())

edited Apr 22 '18 at 07:20

Andrew Rasmussen

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answered Jan 03 '11 at 18:20

spinon

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1

And the stackoverflow question I posted above shows an example. The questions were identical. – JohnMerlino Jan 03 '11 at 18:22
29

A simpler way: `if( +d1 == +d2 )` – GetFree Jul 01 '15 at 20:32

score 24 · Answer 2 · answered Sep 11 '13 at 13:56

24

If you don't want to call getTime() just try this:

(a >= b && a <= b)

answered Sep 11 '13 at 13:56

devmiles.com

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WTF? Why does that work but the equality operator does not? Where is the sense in that? – Kuepper Sep 20 '13 at 12:56
12

The equality operator checks for reference equality. This means it only returns true if the two variables refer the the same object. If you create two Date objects (`var a = new Date(); var b = new Date();`), they will never be equal. – Tomas Oct 11 '13 at 09:40
Is this not a JS bug or is it a limitation of the equality operator and overloading ability? – Josh M. Oct 29 '13 at 20:41
2

This is what equality does for objects, it checks references. – devmiles.com Oct 30 '13 at 11:00
5

@devmiles.com except for string, that are compared by value also, `var a ="str1"; var b = "str"+"1"; a == b // true` – amd Jun 18 '14 at 11:57
11

wierd. You would have thought this would have actually been a place where a seperation between == and === would make sense... Oh wait its javascript. We dont do sense here! – JonnyRaa Aug 13 '14 at 11:13
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@Towa, That works because the >= and <= operators only work on numbers, so they try to convert their operands to numbers. And to convert an object (such as a Date) to a number, JavaScript calls the valueOf() function to get a numeric representation. valueOf() returns the same thing as getTime(): https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/valueOf – Mike Schenk Dec 09 '16 at 21:34

score 3 · Answer 3 · answered Mar 21 '17 at 19:57

3

var d1 = new Date($('#datein').val());
var d2 = new Date($('#dateout').val());

use two simple ways to check equality

if( d1.toString() === d2.toString())
if( +d1 === +d2)

answered Mar 21 '17 at 19:57

Arjun Kubendran

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score 0 · Answer 4 · answered Aug 08 '23 at 16:08

0

Instead of comparing the dates directly, you can check that their difference is zero.

if (d1 - d2 === 0)

answered Aug 08 '23 at 16:08

Liam Bohl

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score -3 · Answer 5 · answered Feb 08 '21 at 03:36

-3

var date = Wed Oct 07 2015 19:48:08 GMT+0200 (Central European Daylight Time);

var dateOne = new Date(date);
var dateTwo = new Date();

var isEqual = dateOne.getDate() === dateTwo.getDate()

this will give you the dates equality

answered Feb 08 '21 at 03:36

Jack Van

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The community encourages adding explanations alongisde code, rather than purely code-based answers (see [here](https://meta.stackoverflow.com/questions/300837/what-comment-should-i-add-to-code-only-answers)). – costaparas Feb 08 '21 at 05:30
3

This is wrong. The 7th April is not the same as the 7th March. – Mark Fisher Apr 07 '21 at 20:45

Determining Date Equality in Javascript

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