Day Numbers

Use datetime.now().timetuple().tm_yday. For a specific date: datetime(2024, 7, 1).timetuple().tm_yday returns 183.

const d = new Date(); const start = new Date(d.getFullYear(), 0, 0); const diff = d - start; const oneDay = 1000 * 60 * 60 * 24; const dayOfYear = Math.floor(diff / oneDay); — this returns 1-based day number.

In a non-leap year, day 60 is March 1. In a leap year, day 60 is February 29 (the leap day itself). So all days from March 1 onward are shifted by one day number in a leap year.

Add the day number minus 1 to January 1 of the year. In Python: datetime(year, 1, 1) + timedelta(days=day_number - 1). In JavaScript: new Date(year, 0, day_number).