Then assemble all week date range of data, the drop-down list (such as "x-xxxx in Week / xx month / xx day")

1  // Week 
2  var Options = ""; // for binding circumferential drop down 
. 3  var SetWFD = 1; // set one week from Monday to Sunday starting 7 
. 4  var firstDayOfYear = new new a Date (yearSelected, 0, 1) ; // New Year's Day 
5  var ? YDDayOfWeek = firstDayOfYear.getDay () == 0 7: firstDayOfYear.getDay (); // Sunday needs to be translated into seven, or computing would be more trouble 
6  var addDays YDDayOfWeek => SetWFD (7 -? (YDDayOfWeek - SetWFD)): (SetWFD - YDDayOfWeek);
 7 firstDayOfYear.addDays (addDays); // first week of the year is: for the first time after a week start day of the week (such as Monday to start day for the week , then the New Year for the first time Monday that week is the first week) 
8  var day = firstDayOfYear.clone();
 9 var weekNum = 1;
10 while (day.getFullYear() == firstDayOfYear.getFullYear()) {
11     var startTime = day;
12     var start = startTime.Format("yyyy/MM/dd");
13     var endTime = startTime.clone();
14     endTime.addDays(6);
15     var end = endTime.Format("yyyy/MM/dd");
16     if ((startTime <= now && now < endTime) || (weekNum == 1 && ((startTime < now && endTime < now) || (startTime > now && endTime > now)))) {
17         selectItem = start + '-' + end;
18         options += '<option value="' + start + '-' + end + '" selected="selected">第' + weekNum + '周(' + start + '-' + end + ')</option>';
19     } else {
20         options += '<option value="' + start + '-' + end + '">第' + weekNum + '周(' + start + '-' + end + ')</option>';
21     }
22     weekNum++;
23     day.addDays(7);
24 }

Use discretion

https://www.cnblogs.com/5MBPerSec/p/12154882.html  wherein reference herein addDays