comparing javascript dates

Question

I have two javascript dates and I want to know if they're the same date. The two dates can be for the same date but have different times: Date1 can be set for 3PM while Date2 can be set for 1AM.

I tried these two options but neither work:

// doesn't work when same date but different time
if (Date1.getTime() === Date2.getTime()) 

// gives true when dates are in different months
if (Date1.getUTCDate() === Date2.getUTCDate())

What the best way to get true when Date1 and Date2 are the same day, regardless of the actual time within the day?

Thanks.

frenchie · Accepted Answer · 2012-11-15 20:05:22Z

1

You can get the day, month and year of the dates and check if they are equal.

if (date1.getUTCDate() == date2.getUTCDate() && 
    date1.getUTCMonth() == date2.getUTCMonth() && 
    date1.getUTCFullYear() == date2.getUTCFullYear()) {
 // dates are on the same day
}

edited Nov 15, 2012 at 20:05

frenchie

52.3k117 gold badges321 silver badges531 bronze badges

answered Nov 15, 2012 at 19:55

Aamir

5,4602 gold badges32 silver badges47 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

frenchie Over a year ago

Shouldn't it be getDate() ?? I edit your answer. It seems to be the best way to do it.

Aamir Over a year ago

@frenchie: Yes, you are correct. getDay() gets the day of the week which wouldn't work. Thanks for fixing it! :)

Daniel A. White · Accepted Answer · 2012-11-15 19:51:16Z

1

Why don't you use toDateString for your comparison?

answered Nov 15, 2012 at 19:51

Daniel A. White

192k49 gold badges389 silver badges473 bronze badges

2 Comments

frenchie Over a year ago

Is there a catch with UTC comparison?

frenchie Over a year ago

I've been burned with UTC and Local before.

J. K. · Accepted Answer · 2012-11-15 19:55:37Z

1

var equalDates = function (a, b) {
  var a_time = a.getTime();
  var b_time = b.getTime();

  var a_days = Math.floor(a_time / (24 * 3600 * 1000));
  var b_days = Math.floor(b_time / (24 * 3600 * 1000));

  return (a_days === b_days);
};

You first get the times in miliseconds. Then you round down to days (since 1970-01-01) and compare those.

answered Nov 15, 2012 at 19:55

J. K.

8,3781 gold badge38 silver badges36 bronze badges

Comments

Chase · Accepted Answer · 2012-11-15 20:15:52Z

1

Use the setHours: function on your date object and set hours, minutes, seconds and milliseconds to zero:

var today = new Date().setHours(0,0,0,0)

For your specific example, you could use:

if(date1.setHours(0,0,0,0) === date2.setHours(0,0,0,0))

where date1 and date2 are your date objects.

setHours:

Sets the hours for a specified date according to local time, and returns the number of milliseconds since 1 January 1970 00:00:00 UTC until the time represented by the updated Date instance.

EXAMPLE:

var today1 = new Date().setHours(0,0,0,0); 
var today2 = new Date().setHours(1,0,0,0); //notice the 1 here

var today3 = new Date().setHours(0,0,0,0); 
var today4 = new Date().setHours(0,0,0,0);

console.log(today1 === today2); //returns false
console.log(today3 === today4); //returns true

edited Nov 15, 2012 at 20:15

answered Nov 15, 2012 at 20:03

Chase

29.6k1 gold badge52 silver badges49 bronze badges

4 Comments

Chase Over a year ago

@frenchie - The concept is much cleaner than checking each element of the date independently.

frenchie Over a year ago

True but look at the number of lines and the gymnastics involved. In truth, it's a matter of personal preference but I prefer less code. I know it works, which is why I upvoted.

Chase Over a year ago

@frenchie - I completely understand. Although the number of lines is simply a "for instance" and can be reduced to merely if(date1.setHours(0,0,0,0) === date2.setHours(0,0,0,0)) where date1 and date2 are your date objects. Either way, I can't argue with personal preference :D

frenchie Over a year ago

Yup, programming is part science, part art. Thanks for your answer; I might use the concept of date1.setHours(0,0,0,0) in other parts of my future code. Happy coding!

Collectives™ on Stack Overflow

comparing javascript dates

4 Answers 4

2 Comments

2 Comments

Comments

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

2 Comments

2 Comments

Comments

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related