JavaScript's getDate returns wrong date

The Date.parse method is implementation dependent (new Date(string) is equivalent to Date.parse(string)).

While this format will be available on modern browsers, you cannot be 100% sure that the browser will interpret exactly your desired format.

I would recommend you to manipulate your string, and use the Date constructor with the year, month and day arguments:

// parse a date in yyyy-mm-dd format
function parseDate(input) {
  var parts = input.match(/(\d+)/g);
  // new Date(year, month [, date [, hours[, minutes[, seconds[, ms]]]]])
  return new Date(parts[0], parts[1]-1, parts[2]); // months are 0-based
}

It's a daylight saving time issue, because Date() uses local time.

I live in Brazil and Oct-21-2012 is the start of daylight saving time in most of my country, so local dates at Oct-21-2012 between 0:0 and 1:0 doesn't exist in Brazil!

Some people comment here that it works. It happens because the right or wrong hour return depends on the local user country.

See: http://www.timeanddate.com/news/time/brazil-dst-2012.html

In Brazil, in 2012 Java thinks that DST starts at Oct-14 (actually it start at 1 week later)

var dt = new Date(2012,9,14); 
alert(dt.getHours());

produces 1 and

See: http://www.timeanddate.com/time/dst/2013.html

The solution is use UTC (Coordinated Universal Time) time, because there is no Daylight Saving changes and you use a kind of abstract time. In most practical applications there is no problem.

var dt = new Date( Date.UTC(2012, 9, 21, 8, 5, 12));
alert( (dt.getUTCMonth()+1) + '/' + dt.getUTCDate() + '/' + 
        dt.getUTCFullYear() + " " + dt.getUTCHours()+ ':' + 
        dt.getUTCMinutes() + ':' + dt.getUTCSeconds() );

it's easier if someone doesn't use hours, minutes and seconds, just place a dummy hour value greater or equal than 1, as I have shown above.

Any chance it's treating the string argument as UTC and the resulting Date object as local time, or vice versa? That could throw it off. Compare d.getDate() to d.getUTCDate().