Comments on: Timezone/DST handling in Javascript

By: Eyal

Eyal — Mon, 28 Dec 2009 16:00:16 +0000

Hi,

There is a potential problem (that unfortunately happened to me), with the float calculations.
If for example (now_utc – now_local.getTime()) / (1000 * 3600)

results in 4.9999, parseInt would result in now_diff=4 instead of the desired 5. I changed it to Math.round and it seemed to solve the problem.

By: l8nite

l8nite — Fri, 28 Aug 2009 19:29:16 +0000

After debugging a little I think you just need to change “new Date.UTC(…)” to “Date.UTC(…)”. I also added Milliseconds, since the Date object supports it.

By: l8nite

l8nite — Fri, 28 Aug 2009 19:23:05 +0000

Actually, now it doesn’t seem to work for any valid DST datetime…

By: l8nite

l8nite — Fri, 28 Aug 2009 18:25:35 +0000

/* unit tests */
var aDSTTests = [
// U.S.: 1987 - 2006
[ "Apr 02, 2006 01:59:00", false ],
[ "Apr 02, 2006 02:00:00", true ],
[ "Oct 29, 2006 01:59:00", true ],
[ "Oct 29, 2006 02:00:00", false ],

// U.S.: 2007 -
[ "Mar 11, 2007 01:59:00", false ],
[ "Mar 11, 2007 02:00:00", true ],
[ "Nov 04, 2007 01:59:00", true ],
[ "Nov 04, 2007 02:00:00", false ],
];

for (var i = 0; i < aDSTTests.length; i++)
{
var sDate = aDSTTests[i][0];
var bFlag = aDSTTests[i][1];
var oDate = new Date(sDate);

print(oDate);

if (oDate.getDST() != bFlag) {
print("FAIL: " + sDate + ", expected " + (bFlag ? 'on' : 'off'));
}
else {
print("PASS: " + sDate + ", expected " + (bFlag ? 'on' : 'off'));
}

if (i != aDSTTests.length – 1) {
print();
}
}

By: l8nite

l8nite — Fri, 28 Aug 2009 18:24:56 +0000

Actually, same results with the new code. Here’s what I’m using to test it:

/* unit tests */
var aDSTTests = [
// U.S.: 1987 - 2006
[ "Apr 02, 2006 01:59:00", false ],
[ "Apr 02, 2006 02:00:00", true ],
[ "Oct 29, 2006 01:59:00", true ],
[ "Oct 29, 2006 02:00:00", false ],

// U.S.: 2007 -
[ "Mar 11, 2007 01:59:00", false ],
[ "Mar 11, 2007 02:00:00", true ],
[ "Nov 04, 2007 01:59:00", true ],
[ "Nov 04, 2007 02:00:00", false ],
];

for (var i = 0; i < aDSTTests.length; i++)
{
var sDate = aDSTTests[i][0];
var bFlag = aDSTTests[i][1];
var oDate = new Date(sDate);

print(oDate);

if (oDate.getDST() != bFlag) {
print("FAIL: " + sDate + ", expected " + (bFlag ? 'on' : 'off'));
}
else {
print("PASS: " + sDate + ", expected " + (bFlag ? 'on' : 'off'));
}

if (i != aDSTTests.length – 1) {
print();
}
}

By: l8nite

l8nite — Fri, 28 Aug 2009 18:03:42 +0000

Thanks for the fix! Is there a particular license on this code?

By: l8nite

l8nite — Tue, 25 Aug 2009 21:19:17 +0000

FAIL: Mar 11, 2007 01:59:00, expected off
PASS: Mar 11, 2007 02:00:00, expected on
FAIL: Nov 04, 2007 01:59:00, expected on
PASS: Nov 04, 2007 02:00:00, expected off