Creating date with 31 as day gives 30 in output

Question

I'm creating dates from strings with the format 'yyyy-MM-dd' but they're always created on the previous day for some reason. If I set the date as '2012-10-31' the Date object with actually be 30 of October and not 31. For example, this:

var d1=new Date('2012-10-31');

Will output this:

Tue Oct 30 2012 19:30:00 GMT-0430 (Venezuela Standard Time)

Can someone explain why this happens?

How can I compensate then? To get the time in my actual timezone? — 8vius, Oct 31 '12 at 13:42
Look at [this question](http://stackoverflow.com/questions/7556591/javascript-date-object-always-one-day-off). — undefined, Oct 31 '12 at 13:47

score 1 · Answer 1 · answered Oct 31 '12 at 13:45

1

Try this

var d1=new Date(2012, 10-1, 31, 0, 0 ,0);
document.write(d1);

which produces

Wed Oct 31 2012 00:00:00 GMT-0400 (Eastern Daylight Time)

the key is to remove the quotes and manually set the time. Also note that 'month' is zero based and so for readability I subtract one from it

answered Oct 31 '12 at 13:45

Eonasdan

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I see the problem now, since the date isn't getting created with any time information is just takes it as GMT 0000 and rolls it back to my timezone. – 8vius Oct 31 '12 at 13:47

score 1 · Answer 2 · answered Oct 31 '12 at 13:48

1

This happens because dates are converted to a string based on your local time zone.

The date variable actually contains October 31st 0:00 UTC. When you convert it to string, it is converted using your own time-zone, which is 4:30 hours behind UTC.

answered Oct 31 '12 at 13:48

zmbq

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Nippey · Accepted Answer · 2012-10-31T14:22:43.680

With no further parameters, Date() create your time-stamp with GMT+0000.

Converting your date to string with no further parameters either, it will use the localised notation.
If you want to create a date matching your time-zone, do:

var d1=new Date('2012-10-31 GMT-0430');
//That's what you should get
//"Wed Oct 31 2012 00:00:00 GMT-0430"

Using this date now, you can convert the local time to the time of other timezones if you execute d1.toString() in a browser with a different timezone:

d1.toString();
//That's what I get
//"Wed Oct 31 2012 05:30:00 GMT+0100"

Creating date with 31 as day gives 30 in output

3 Answers3