JavaScript gets the day, week, month, year start and end time

1. 1. 
      /**
      * Get start date, end date for this week, quarter, month, month
      */
      var now = new Date (); Current date
      var nowdayofweek = Now.getday (); The day of the week today
      var nowday = Now.getdate (); Current day
      var nowmonth = Now.getmonth (); Current month
      var nowyear = Now.getyear (); When the year before
      Nowyear + = (Nowyear < 2000)? 1900:0; //
      
      
      var lastmonthdate = new Date (); Last month date
      Lastmonthdate.setdate (1);
      Lastmonthdate.setmonth (Lastmonthdate.getmonth ()-1);
      var lastyear = Lastmonthdate.getyear ();
      var lastmonth = Lastmonthdate.getmonth ();
      
      Formatted Date: YYYY-MM-DD
      function FormatDate (date) {
      var myyear = Date.getfullyear ();
      var mymonth = Date.getmonth () +1;
      var myweekday = Date.getdate ();
      
      if (Mymonth < 10) {
      Mymonth = "0" + mymonth;
      }
      if (Myweekday < 10) {
      Myweekday = "0" + myweekday;
      }
      Return (myyear+ "-" +mymonth + "-" + myweekday);
      }
      
      Get the number of days in a month
      function Getmonthdays (mymonth) {
      var monthstartdate = new Date (Nowyear, Mymonth, 1);
      var monthenddate = new Date (nowyear, Mymonth + 1, 1);
      var days = (monthenddate-monthstartdate)/(1000 * 60 * 60 * 24);
      return days;
      }
      
      Get the start month of the quarter
      function Getquarterstartmonth () {
      var quarterstartmonth = 0;
      if (nowmonth<3) {
      Quarterstartmonth = 0;
      }
      if (2<nowmonth && nowmonth<6) {
      Quarterstartmonth = 3;
      }
      if (5<nowmonth && nowmonth<9) {
      Quarterstartmonth = 6;
      }
      if (nowmonth>8) {
      Quarterstartmonth = 9;
      }
      return quarterstartmonth;
      }
      
      Get the start date for this week
      function Getweekstartdate () {
      var weekstartdate = new Date (nowyear, Nowmonth, Nowday-nowdayofweek);
      return FormatDate (weekstartdate);
      }
      
      Get the end date for this week
      function Getweekenddate () {
      var weekenddate = new Date (nowyear, Nowmonth, Nowday + (6-nowdayofweek));
      return FormatDate (weekenddate);
      }
      
      Get the start date for this month
      function Getmonthstartdate () {
      var monthstartdate = new Date (Nowyear, Nowmonth, 1);
      return FormatDate (monthstartdate);
      }
      
      Get the end date for this month
      function Getmonthenddate () {
      var monthenddate = new Date (nowyear, Nowmonth, Getmonthdays (Nowmonth));
      return FormatDate (monthenddate);
      }
      
      
      Get start time last month
      function Getlastmonthstartdate () {
      var lastmonthstartdate = new Date (Nowyear, Lastmonth, 1);
      return FormatDate (lastmonthstartdate);
      }
      
      
      Get last month end time
      function Getlastmonthenddate () {
      var lastmonthenddate = new Date (nowyear, Lastmonth, Getmonthdays (Lastmonth));
      return FormatDate (lastmonthenddate);
      }
      
      Get the start date for the quarter
      function Getquarterstartdate () {
      
      var quarterstartdate = new Date (Nowyear, Getquarterstartmonth (), 1);
      return FormatDate (quarterstartdate);
      }
      
      Or the end date of the quarter
      function Getquarterenddate () {
      var quarterendmonth = Getquarterstartmonth () + 2;
      var quarterstartdate = new Date (nowyear, Quarterendmonth, Getmonthdays (Quarterendmonth));
      return FormatDate (quarterstartdate);
      }
      
      

JavaScript gets the day, week, month, year start and end time