28

I have an issue -

The javascript Date("mm-dd-yyyy") constructor doesn't work for FF. It works fine for IE.

  • IE : new Date("04-02-2008") => "Wed Apr 2 00:00:00 EDT 2008"
  • FF2 : new Date("04-02-2008") => Invalid Date

So lets try another constructor. Trying this constructor Date("yyyy", "mm", "dd")

  • IE : new Date("2008", "04", "02"); => "Fri May 2 00:00:00 EDT 2008"
  • FF : new Date("2008", "04", "02"); => "Fri May 2 00:00:00 EDT 2008"
  • IE : new Date("2008", "03", "02"); => "Wed Apr 2 00:00:00 EDT 2008"
  • FF : new Date("2008", "03", "02"); => "Wed Apr 2 00:00:00 EDT 2008"

So the Date("yyyy", "mm", "dd") constructor uses an index of 0 to represent January.

Has anyone dealt with this?
There must be a better way than subtracting 1 from the months.

Wayne
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Brad8118
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6 Answers6

45

It is the definition of the Date object to use values 0-11 for the month field.

I believe that the constructor using a String is system-dependent (not to mention locale/timezone dependent) so you are probably better off using the constructor where you specify year/month/day as seperate parameters.

BTW, in Firefox, 

new Date("04/02/2008");

works fine for me - it will interpret slashes, but not hyphens. I think this proves my point that using a String to construct a Date object is problemsome. Use explicit values for month/day/year instead:

new Date(2008, 3, 2);
matt b
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17

nice trick indeed, which i just found out the hard way (by thinking thru it). But i used a more natural date string with hyphen :-)

var myDateArray = "2008-03-02".split("-");
var theDate = new Date(myDateArray[0],myDateArray[1]-1,myDateArray[2]); 
alert(theDate);
joedotnot
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3

Using

var theDate = new Date(myDate[0],myDate[1]-1,myDate[2]);

Is fine, but it shows some strange behaviors when month and day values are erroneous.

Try casting a date where both myDate[1]-1 and myDate[2] have values of 55. Javascript still returns a date, though the input is obviously not correct.

I would have preferred javascript to return an error in such a case.

Bruno Vieira
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Frank
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2

@Frank: you are right. When you need to validate date,

var theDate = new Date(myDate[0],myDate[1]-1,myDate[2]);

will not work.

What happens is that it keeps on adding the extra parameter. For example:

new Date("2012", "11", "57") // Date {Sat Jan 26 2013 00:00:00 GMT+0530 (IST)}

Date object takes the extra days (57-31=26) and adds it to the date we created.

Or if we try constructing a date object with:

new Date("2012", "11", "57", "57") //Date {Mon Jan 28 2013 09:00:00 GMT+0530 (IST)}

an extra 2 days and 9 hours (57=24+24+9) are added.

Umber Ferrule
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Constantine M
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1

You're quite right, month is indicated as an index, so January is month number 0 and December is month number 11 ...

-- and there is no work-around as it is stated clearly in the ECMA-script-definition, though simple tricks commonly will work:

var myDate = "2008,03,02".split(",");
var theDate = new Date(myDate[0],myDate[1]-1,myDate[2]); 
alert(theDate);
roenving
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0

Bold statement.

This might have your interest: JavaScript Pretty Date.

cllpse
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