Calculate start/end dates for common ranges in Javascript.

date_ranges.js

  // Calculate and set ranges: today, yesterday, this week, past week, this month, past month, this year
  switch(newValue) {
      case 'today':
          initial_date.setValue(new Date());
          end_date.setValue(new Date());
          break;
      case 'yesterday':
          var d = new Date();
          d.setDate(d.getDate() - 1);
          initial_date.setValue(d);
          end_date.setValue(d);
          break;
      case 'thisweek':
          var d = new Date();
          var first = d.getDate() - d.getDay() + 1;
          var last = first + 6;
          initial_date.setValue(new Date(d.setDate(first)));
          end_date.setValue(new Date(d.setDate(last)));
          break;
      case 'pastweek':
          var d = new Date();
          var first = d.getDate() - d.getDay() - 7 + 1;
          var last = first + 6;
          initial_date.setValue(new Date(d.setDate(first)));
          end_date.setValue(new Date(d.setDate(last)));
          break;
      case 'thismonth':
          var date = new Date(), y = date.getFullYear(), m = date.getMonth();
          initial_date.setValue(new Date(y, m, 1));
          end_date.setValue(new Date(y, m + 1, 0));
          break;
      case 'pastmonth':
          var date = new Date(), y = date.getFullYear(), m = date.getMonth() - 1;
          initial_date.setValue(new Date(y, m, 1));
          end_date.setValue(new Date(y, m + 1, 0));
          break;
      case 'thisyear':
          var date = new Date(), y = date.getFullYear();
          initial_date.setValue(new Date(y, 0, 1));
          end_date.setValue(new Date(y, 11, 31));
          break;
      default:
          break;
  }