javascript to parse ISO-8601 date format

ParseISO8601.js

function ParseISO8601(iso)
{
	// 0 = whole string
	// 1 = year
	// 2 = month
	// 3 = day
	// 4 = whole time part
	// 5 = hour
	// 6 = minute
	// 7 = second
	// 8 = fractional (with dot)
	// 9 = whole timezone (possibly Z)
	// 10 = offset sign (+ or -)
	// 11 = offset hours
	// 12 = offset minutes (with colon)
	// 13 = offset minutes
	_rxISO : /^(\d{4})-(\d\d)-(\d\d)([T ](\d\d):(\d\d):(\d\d)(\.\d+)?(Z|([+-])(\d\d)(:(\d\d))?)?)?$/,
		
	var r = System.Date._rxISO.exec(iso);
	if (!r)
		return new Date(Date.parse(iso));

	var year = Number(r[1]), month = Number(r[2]) - 1, day = Number(r[3]);
	if (!r[4])
		return new Date(year, month, day);

	var hour = Number(r[5]), minute = Number(r[6]), second = Number(r[7]);
	var ms = r[8]? Number((r[8] + "000").substr(1, 3)): 0;
	if (!r[9])
		return new Date(year, month, day, hour, minute, second, ms);

	var oh = r[11]? Number(r[10]) + Number(r[11]): 0;
	var om = r[13]? Number(r[10]) + Number(r[13]): 0;
	hour -= oh;
	minute -= om;
	return new Date(Date.UTC(year, month, day, hour, minute, second, ms));
}