wrong day when adding a year

[mdbaniani]

var start = moment('1370/1/1', 'jYYYY/jM/jD').add(1, 'jYear');
console.log(start.format('jYYYY/jM/jD'))

will result in : 1370/12/30

I expected : 1371/1/1.

Is this expected behavior? please correct me if I am wrong

also:

moment('1370/12/30', 'jYYYY/jM/jD').jMonth() should result in 12 but returns 11.

[mdbaniani]

apparently, setting noon time (12:00) for date object before manipulating, solved the problem:

start.set("hour", 12).set("minute", 0);

[behrang]

This must be the daylight saving time interfering. It's better to set a time in this case. Also, months are zero-based in moment.