Calculate correct current AEST/ADST time

current-au-nsw-time.js

var getCurrentAestDate = function ( ) {
	var d = new Date(),
		timezone = 10,
		utc = d.getTime() - ( d.getTimezoneOffset() * 60000 ),
		// Current +10 (AEST) time
		aest = new Date( utc + (3600000 * -timezone) ),
		// Current +11 (ADST) time
		adst = new Date( utc + (3600000 * -(timezone+1)) ),
		// Set to start of the month DST starts (October)
		// and time of rollover (0200)
		dstStart = new Date(aest.getFullYear(), (10-1), 1, 2, 0, 0, 0),
		// Set to start of the month DST ends (April)
		// and time of rollover (0300)
		dstEnd = new Date(aest.getFullYear(), (04-1), 1, 3, 0, 0, 0);

	// Now, calculate the position of the first Sunday of the start and end month,
	// which is when DST actually starts, or ends.
	// One of 1001 great uses for mod!
	dstStart.setDate( dstStart.getDate() + ((7 - dstStart.getDay()) % 7) );
	dstEnd.setDate( dstEnd.getDate() + ((7 - dstEnd.getDate()) % 7) );

	// Now we simply check if the current date is between the two regions
	// If ADST is after the end datetime and AEST is before the start datetime,
	// then DST is not in effect. You have to think about this one a little bit...
	// it matters which clock you check, otherwise you might have incorrect 1 hour
	// edge cases around the start/end datetimes.
	// An alternative and perhaps easier way to calculate all this would be to just
	// work everything out against UTC and do away with the need for two Dates.
	if ( adst.getTime() > dstEnd.getTime() && aest.getTime() < dstStart.getTime() ) {

		// No DST!
		return aest;

	}

	// Yes, DST!
	return adst;

};