if(arguments.length == 1){ firstDayOfWeek = 0; } // Sunday var firstDayOfYear = new Date(dateObject.getFullYear(), 0, 1).getDay(); var adj = (firstDayOfYear - firstDayOfWeek + 7) % 7; var week = Math.floor((dojo.date.locale._getDayOfYear(dateObject) + adj - 1) / 7); // if year starts on the specified day, start counting weeks at 1 if(firstDayOfYear == firstDayOfWeek){ week++; } return week; // Number