first and last saturday of a month

I’m working on an expenses application. In order to do it, I need to display the entire month, with full weeks in each (from Saturday to Friday).

To do this, I need to know what date the Saturday in the first week falls, and the date of the first Saturday in the following month.

Here’s the code (assuming year is a 4-digit year, and month is a 1-12 number):

      // { start date
      var start=new Date(year, month-1, 1);
      var day=start.getDay();
      day=(day+1)%7; 

      start=new Date(start-3600000*24*day);

      // }
      // { end date
      month++;
      if (month==13) {
        month=1;
        year++;
      }
      var end=new Date(year, month-1, 1);
      var day=end.getDay();
      day=7-((day+1)%7);

      end=new Date((+end)+3600000*24*day);

      // }

can’t be bothered explaining it – just trust that it’s right Image may be NSFW.
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