This is my code:

var d = new Date();
var date = 29;
var month = 1; // Feb
var year = 2012; // Bissextile year
d.setUTCDate(date);
d.setUTCMonth(month);
d.setUTCFullYear(year);
d.setUTCHours(0);
d.setUTCMinutes(0);
d.setUTCSeconds(0);
document.write(d.getUTCDate()+"<br />"+d.getUTCMonth()+"<br />"+d);

This is the result in Firefox:

1
2
Thu Mar 01 2012 11:00:00 GMT+1100 (AUS Eastern Standard Time)

When the value of date is 28:

28
1
Tue Feb 28 2012 11:00:00 GMT+1100 (AUS Eastern Standard Time)

There is no Wednesday!

Is it an error of JS or there is another method to find Wed Feb 29 2012 here?

This is my code:

var d = new Date();
var date = 29;
var month = 1; // Feb
var year = 2012; // Bissextile year
d.setUTCDate(date);
d.setUTCMonth(month);
d.setUTCFullYear(year);
d.setUTCHours(0);
d.setUTCMinutes(0);
d.setUTCSeconds(0);
document.write(d.getUTCDate()+"<br />"+d.getUTCMonth()+"<br />"+d);

This is the result in Firefox:

1
2
Thu Mar 01 2012 11:00:00 GMT+1100 (AUS Eastern Standard Time)

When the value of date is 28:

28
1
Tue Feb 28 2012 11:00:00 GMT+1100 (AUS Eastern Standard Time)

There is no Wednesday!

Is it an error of JS or there is another method to find Wed Feb 29 2012 here?

• javascript
• time

Share Improve this question Follow asked Mar 5, 2014 at 13:26 KaiKai 15511 gold badge22 silver badges1313 bronze badges 1

• it's not a bug, it's a feature – Sergio Commented Mar 5, 2014 at 13:47

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1 Answer 1

Sorted by: Reset to default 10

The problem is the order in which you are setting the items.

You're starting from today, which is March 5th, 2014.

You are then setting the date to 29. Result: March 29th, 2014.

Then you set the month to 1. Result: Feburary 29th, 2014. Oh wait, that's wrong because 2014 is not a leap year, so JS corrects it to March 1st, 2014.

Finally, you set the year. Final result is March 1st, 2012.

Try setting the year first, then the day, then the month.

Alternatively, use the constructor properly: new Date(2012,1,29) should work just fine.