how to calculate "time 1" - "time 2" in JavaScript?

Question

Friends,

I would like to calculate difference between two times. For example I have

var workedHours = '05:00:00';

var defaultWorkDay = '08:00:00';

So I'm needing to calc workedHours - defaultWorkDay and expect a '-03:00:00' result.

I've tried moment.js but with no success.

Do you have some suggestion?

possible duplicate of [Check time difference in Javascript](http://stackoverflow.com/questions/1787939/check-time-difference-in-javascript) — Cheery, Nov 17 '14 at 21:38
moment.js should handle this beautifully. Can you post the moment.js-based code you tried? — DeeDee, Nov 17 '14 at 21:38
If you actually tried something, you should post that code and explain how you expected it to work, and what happened instead. — Pointy, Nov 17 '14 at 21:41
Would you be able to convert the hours into time (like a Unix timestamp), do your arithmetic, and then convert the difference into hours? — mts7, Nov 17 '14 at 21:45
@Pointy I've tried. `var worked = moment.utc("2014-11-18 05:00:00","YYYY-MM-DD HH:mm:ss");` `var defaultDay = moment.utc("2014-11-18 08:00:00", "YYYY-MM-DD HH:mm:ss"); ` `var diff = moment.utc(worked).diff(moment.utc(defaultDay));` diff is "0" — quicoli, Nov 18 '14 at 09:37
@NabilKadimi What?! Your statement makes no sense. If you're suggesting that moment.js is in fact not a good solution, I'll point you to the first accepted answer, written by a person who never used the framework yet immediately saw how to use it. — DeeDee, Nov 18 '14 at 17:15

score 1 · Accepted Answer · edited Nov 17 '14 at 22:31

1

I never used moment.js , but I think this should work for you:

    var defaultWorkDay = '08:00:00';
    var workedHours = '05:00:00';
    var a = moment.duration(defaultWorkDay);
    var b = moment.duration(workedHours);
    
    console.log( [ b.subtract(a).hours(), b.subtract(a).minutes(), b.subtract(a).seconds() ]
    ) // [-3:0:0]

<script src="http://momentjs.com/downloads/moment.min.js"></script>

http://momentjs.com/docs/#/durations/subtract/

edited Nov 17 '14 at 22:31

Nabil Kadimi

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answered Nov 17 '14 at 21:51

I believe that adding 31 KB (minified) for such a basic operation is unnecessary. – Nabil Kadimi Nov 17 '14 at 21:57
I modified to work with minutes and seconds as well. – Nabil Kadimi Nov 17 '14 at 22:01
to work properly: `var diff = b.subtract(a);` `var hour = diff.hours();` `var minute = diff.minutes();` `var second = diff.seconds();` – quicoli Nov 18 '14 at 10:29

Nabil Kadimi · Answer 2 · 2014-11-17T22:01:53.433

You can do this like this if you are sure the format is always hours:minutes:secnodes...:

var start = "05:00:00";
var end = "08:00:00";

var startArr = start.split(':');
var endArr = end.split(':'); 

var diffInSeconds = 0
    + ( endArr[0] - startArr[0] ) * 3600
    + ( endArr[1] - startArr[1] ) * 60
    + ( endArr[2] - startArr[2] ) ;

console.log ( 'The difference is : ' + diffInSeconds + ' seconds.');

// => The difference is 10800 seconds.

score 0 · Answer 3 · answered Nov 17 '14 at 22:00

Turn your hours into dates with time by prefixing them with a date (like below) and then do math using .getTime() on the Date object. Then convert those milliseconds into your hours, or whatever other time unit you desire.

  var date1 = new Date("2000-01-01 05:00:00");
  var date2 = new Date("2000-01-01 08:00:00");
  var msTimeOffset = date1.getTime() - date2.getTime();
  var hourTimeOffset = msTimeOffset / 1000 / 60 / 60;
  expect(hourTimeOffset).toBe(-3); // passes

how to calculate "time 1" - "time 2" in JavaScript?

3 Answers3