Calculate duration between two date times in javascript

Question

I need to calculate the duration between two datetimes in JavaScript. I have tried this code:

var today = new Date();
var dd = today.getDate();
var mm = today.getMonth()+1; //January is 0!

var yyyy = today.getFullYear();
if(dd<10){dd='0'+dd} if(mm<10){mm='0'+mm} today = mm+'/'+dd+'/'+yyyy;  //Current Date
console.log("current date"+today);


var valuestart ="8:00 AM";
var valuestop = "4:00 PM";//$("select[name='timestop']").val();

//create date format          
var timeStart = new Date("01/01/2007 " + valuestart).getHours();
var timeEnd = new Date("01/01/2007 " + valuestop).getHours();

var hourDiff = timeEnd - timeStart;             
console.log("duration"+hourDiff);

From this, I am able to get Current Date and duration. But when I replace the date "01/01/2007" with the variable "today", I am getting the result as NaN. Please guide me in where I am wrong. Thanks in advance.

Show us the code that's not working. Right now 'today' is a Date object — Geoffrey Burdett, Feb 04 '14 at 14:05
Its correct in the above code.But when i change that into var timeStart=new Date(""+today+""+valuestart+"").getHours(); and similar in timeEnd, i am getting problem — user2247744, Feb 04 '14 at 14:06

score 3 · Answer 1 · edited May 23 '17 at 11:48

You should work on the epoch milliseconds. The idea is to transform everything to the epoch millis representation, perform your calculations, then go back to another format if needed.

There are many articles on the subject:

score 2 · Accepted Answer · answered Feb 04 '14 at 14:13

Try this :

        var today = new Date();
        var dd = today.getDate();
        var mm = today.getMonth()+1; //January is 0!

        var yyyy = today.getFullYear();
        if(dd<10){dd='0'+dd} if(mm<10){mm='0'+mm} today = dd+'/'+mm+'/'+yyyy;  //Current Date

        var valuestart ="8:00 AM";
        var valuestop = "4:00 PM";//$("select[name='timestop']").val();

        //create date format  
        var timeStart = new Date(today + " " + valuestart).getHours();
        var timeEnd = new Date(today + " " + valuestop).getHours();

        var hourDiff = timeEnd - timeStart;  
        alert("duration:"+hourDiff);

score 1 · Answer 3 · answered Feb 04 '14 at 14:08

1

today is of Date type whereas "01/01/2007" is a string. Trying to concatenate a Date object with "8:00 AM" will not work. You will have to turn today variable into a string or use today.setHours(8)

answered Feb 04 '14 at 14:08

KJ Price

5,774
3
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How to convert Date type into string – user2247744 Feb 04 '14 at 14:10
If you have jQuery, it will be easy. $.datepicker.formatDate('mm/dd/yyyy', today); – KJ Price Feb 04 '14 at 14:12
If you do not have jQuery, you will likely have to use the built-in methods from the Date object to build the string: (today.getMonth() + 1) + '/' + today.getDate() + '/' + today.getFullYear(). Something like that. – KJ Price Feb 04 '14 at 14:14
No i have not suppose to use datepicker.I will get the time from server – user2247744 Feb 04 '14 at 14:16

VincentTu · Answer 4 · 2021-12-20T07:41:52.273

0

Maybe It's a little bit late. I second the answer from Christophe Roussy. First, calculate the difference in UTC format, then turn the unit - hour. I think it's easier to understand and maintain. Here's the code

var date1 = new Date(`some_valid_start_date_format`);
var date2 = new Date(`some_end_start_date_format`);

var duration = date2.valueOf() - date1.valueOf(); // The unit is millisecond
var hourDiff = parseInt(duration / (60 * 60 * 1000)) // Turn the duration into hour format

edited Dec 20 '21 at 07:41

answered Dec 29 '20 at 06:16

VincentTu

1
2

Think you need some brackets around that duration line: `parseInt(duration / (60 * 60 * 1000))` – 0atman Dec 15 '21 at 10:52
ok, edited, thx for the correctness – VincentTu Dec 20 '21 at 07:42
Thanks for the answer! Nice and succinct, I used it in my program :-) – 0atman Dec 21 '21 at 09:17

score 0 · Answer 5 · answered Sep 23 '22 at 15:00

0

I tried luxon and it's very handy:

Given dt1 and dt2 as ISO representation of date time,

luxon.DateTime.fromISO(dt1).diff(
  luxon.DateTime.fromISO(dt2),
  ['years', 'months', 'days', 'hours', 'minutes', 'seconds']
).values

answered Sep 23 '22 at 15:00

shawnzhu

7,233
4
35
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Calculate duration between two date times in javascript

5 Answers5