MooTools More "new Date().parse()" yields wrong month in Chrome / WebKit

Question

Consider this snippet using the latest MooTools Core & More 1.5 (view in jsFiddle):

console.log(new Date().parse('2014-09-20 00:00:00'));

When I run this code, I usually get something along the lines of

Sat Sep 20 2014 00:00:00 GMT+0200 (Central Europe Daylight Time)

However, when I use Chrome (38.0.2125.104 m) or a PyQt 4 WebKit window and use a Russian time zone (anything in Windows with an RTZ in its name), the date is 1 month in the future:

Mon Oct 20 2014 00:00:00 GMT+0300 (Eastern Europe Daylight Time)

This apparently does not occur with Firefox or Internet Explorer, or apparently any non-Russian time zone.

Anybody know why ?

Answer 1

The issue is apparently caused by Chrome bugs 417640 and 420269.

Dates between 2014-01-01 00:00:00 (inclusive) and 2014-01-01 01:00:00 (exclusive) simply do not exist as such, they resolve to 2013-12-31 23:00:00 - 2013-12-31 23:59:59 instead.

You can reproduce this with an RTZ:

var d = new Date();

d.setHours(0);
d.setMinutes(0);
d.setSeconds(0);
d.setYear(2014);
d.setDate(1);

d.setMonth(0);
console.log(d.getMonth()); // Yields 11 rather than 0

This is because Date.parse('2014-01-01 00:00:00') yields 2013-12-31 in the date part due to time zone issues.

This bug affects other dates as well because of the way MooTools' Date extensions work (initializing dates with year-01-01 00:00:00 and then subsequently setting extracted values, e.g. 12:34:56 Sep 25, 2014 would be derived like this:

2014-01-01 00:00:00 // Initialization
2013-12-31 23:00:00 // Resolved date with RTZ
2014-12-31 23:00:00 // Year
2014-09-31 23:00:00 // Month
2014-10-01 23:00:00 // Resolved date with overflow
2014-10-25 23:00:00 // Day of month
2014-10-25 12:34:56 // Time