Adding a week to Date in JavaScript: rounding error or daylight savings?

I am trying to add seven days to a Data object, however at some stage I start getting strange results.

var currDate = new Date(2011, 2, 28)
  , oldTicks = currDate.getTime()
  , newTicks = oldTicks + (86400000 * 7)
  , nextWeek = new Date(newTicks)
console.log('Old ticks: ' + oldTicks)
console.log('New ticks: ' + newTicks)
console.log('New date : ' + nextWeek)

The output I get, both Chrome/FF is:

Old ticks: 1301230800000
New ticks: 1301835600000
log: New date : Sun Apr 03 2011 23:00:00 GMT+1000 (EST)

Expected to get:

lo开发者_如何学Gog: New date : Mon Apr 04 2011 23:00:00 GMT+1000 (EST)

As you can see, instead of adding 7 days, just 6 were added. The code above, however, works fine with other dates, say 2011 Apr 28 or 2011 May 28.

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Crescent Fresh is correct form what I can deduce. Looking up timezones GMT+1000 (EST) looks like Australia Eastern Standard Time - from wikipedia - list of timezones by UTC offset

And from wikipedia - daylist savings time around the world, shows that Australia switches from standard to daylight savings time in between the date ranges specified by the OP.

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If it were me I'd do:

var curDate = new Date(),

var aWeekLater = new Date(curDate.getFullYear(), curDate.getMonth(), curDate.getDate() + 7);

with some possible adjustments for time of day.

That said, when I try your code in my Chrome developer console, I get 04 Apr as the answer.