function weekNumber()

in tapestry-framework/src/org/apache/tapestry/form/DatePicker.js [813:851]

• 30 lines of code
• 10 McCabe index (conditional complexity)

function weekNumber(cal, date) {

	var dow = date.getDay();
	var doy = dayOfYear(date);
	var year = date.getFullYear();

	// Compute the week of the year.  Valid week numbers run from 1 to 52
	// or 53, depending on the year, the first day of the week, and the
	// minimal days in the first week.  Days at the start of the year may
	// fall into the last week of the previous year; days at the end of
	// the year may fall into the first week of the next year.
	var relDow = (dow + 7 - cal.getFirstDayOfWeek()) % 7; // 0..6
	var relDowJan1 = (dow - doy + 701 - cal.getFirstDayOfWeek()) % 7; // 0..6
	var week = Math.floor((doy - 1 + relDowJan1) / 7); // 0..53
	if ((7 - relDowJan1) >= cal.getMinimalDaysInFirstWeek()) {
		++week;
	}

	if (doy > 359) { // Fast check which eliminates most cases
		// Check to see if we are in the last week; if so, we need
		// to handle the case in which we are the first week of the
		// next year.
		var lastDoy = yearLength(year);
		var lastRelDow = (relDow + lastDoy - doy) % 7;
		if (lastRelDow < 0) {
			lastRelDow += 7;
		}
		if (((6 - lastRelDow) >= cal.getMinimalDaysInFirstWeek())
			&& ((doy + 7 - relDow) > lastDoy)) {
			week = 1;
		}
	} else if (week == 0) {
		// We are the last week of the previous year.
		var prevDoy = doy + yearLength(year - 1);
		week = weekOfPeriod(cal, prevDoy, dow);
	}

	return week;
}