使用JS获取从周号和年份开始的日期范围，其中每周从星期日开始

Question

我有以下代码来获取一周的开始和结束日期

Date.prototype.getWeek = function() {
  var date = new Date(this.getTime());
  date.setHours(0, 0, 0, 0);
  // Thursday in current week decides the year.
  date.setDate(date.getDate() + 3 - (date.getDay() + 6) % 7);
  // January 4 is always in week 1.
  var week1 = new Date(date.getFullYear(), 0, 4);
  // Adjust to Thursday in week 1 and count number of weeks from date to week1.
  return 1 + Math.round(((date.getTime() - week1.getTime()) / 86400000 - 3 + (week1.getDay() + 6) % 7) / 7);
}

function getDateRangeOfWeek(weekNo, y){
    var d1, numOfdaysPastSinceLastMonday, rangeIsFrom, rangeIsTo;
    d1 = new Date(''+y+'');
    numOfdaysPastSinceLastMonday = d1.getDay() - 1;
    d1.setDate(d1.getDate() - numOfdaysPastSinceLastMonday);
    d1.setDate(d1.getDate() + (7 * (weekNo - d1.getWeek())));
    rangeIsFrom = (d1.getMonth() + 1) + "-" + d1.getDate() + "-" + d1.getFullYear();
    d1.setDate(d1.getDate() + 6);
    rangeIsTo = (d1.getMonth() + 1) + "-" + d1.getDate() + "-" + d1.getFullYear() ;
    return rangeIsFrom + " to " + rangeIsTo;
};

但是在这里，一周从星期一开始。从每周的星期日开始，我该如何实现相同的目标？