How to subtract date time in JavaScript

Question

I have a field at a grid containing date time and I need to know the difference between that and the current date time  What could be the best way of doing so   The dates are stored like  2011-02-07 15 13 06

User · Answer

If you wish to get difference in wall clock time, for local timezone and with day-light saving awareness.


Date.prototype.diffDays = function (date: Date): number {

    var utcThis = Date.UTC(this.getFullYear(), this.getMonth(), this.getDate(), this.getHours(), this.getMinutes(), this.getSeconds(), this.getMilliseconds());
    var utcOther = Date.UTC(date.getFullYear(), date.getMonth(), date.getDate(), date.getHours(), date.getMinutes(), date.getSeconds(), date.getMilliseconds());

    return (utcThis - utcOther) / 86400000;
};

Test


it('diffDays - Czech DST', function () {
    // expect this to parse as local time
    // with Czech calendar DST change happened 2012-03-25 02:00
    var pre = new Date('2012/03/24 03:04:05');
    var post = new Date('2012/03/27 03:04:05');

    // regardless DST, you still wish to see 3 days
    expect(pre.diffDays(post)).toEqual(-3);
});

Diff minutes or seconds is in same fashion.

User · Answer

This will give you the difference between two dates  in milliseconds  var diff   Math abs date1 - date2     In your example  it d be  var diff   Math abs new Date   - compareDate     You need to make sure that compareDate is a valid Date object   Something like this will probably work for you  var diff   Math abs new Date   - new Date dateStr replace  - g           i e  turning  2011-02-07 15 13 06  into new Date  2011 02 07 15 13 06    which is a format the Date constructor can comprehend

User · Answer

You can just substract two date objects   var d1   new Date       now  var d2   new Date  2011 02 01       some date var diff   Math abs d1-d2       difference in milliseconds

User · Answer

Unless you are subtracting dates on same browser client and don t care about edge cases like day light saving time changes  you are probably better off using moment js which offers powerful localized APIs  For example  this is what I have in my utils js   subtractDates  function date1  date2        return moment subtract date1  date2  milliseconds       millisecondsSince  function dateSince        return moment   subtract dateSince  milliseconds

User · Answer

You can use getTime   method to convert the Date to the number of milliseconds since January 1  1970  Then you can easy do any arithmetic operations with the dates  Of course you can convert the number back to the Date with setTime    See here an example

[javascript] How to subtract date/time in JavaScript?

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