获取当周的周六、周日

需求：无论当前是哪一天，获取当天所在周的周末 是哪一天

实现步骤：
比如，今天周一，则周日距离今天还有（7-1）=6天，那么将今天的时间（毫秒数），加上六天后的时间（6*_dayLongTime 毫秒数），然后根据date函数，转换为几月几日。

1、获取当天的时间

let _nowTime=new Date().getTime();

2、获取当天是星期几

let _week=_date.getDay();

3、设置一天的时长

let _dayLongTime=24*60*60*1000;

4、获取周六周日距离现在还有多少毫秒

let  _furtureSundayTimes = _nowTime + (7 - _week) * _dayLongTime;
let  _furtureSaturdayTimes = _nowTime + (6 - _week) * _dayLongTime;

5、将毫秒数转为date对象

_furtureSundayTimes = new Date(_furtureSundayTimes);
_furtureSaturdayTimes = new Date(_furtureSaturdayTimes);

6、根据日期获取几月几日

// staurday
  let _satYear = _furtureSaturdayTimes.getFullYear();
  let _satMonth = _furtureSaturdayTimes.getMonth() + 1;
  let _satDay = _furtureSaturdayTimes.getDate();

  //sunday
  let _sunYear = _furtureSundayTimes.getFullYear();
  let _sunMonth = _furtureSundayTimes.getMonth() + 1;
  let _sunDay = _furtureSundayTimes.getDate();

7、格式化

 _satMonth = _satMonth >= 10 ? _satMonth : '0' + _satMonth;
  _satDay = _satDay >= 10 ? _satDay : '0' + _satDay;

  _sunMonth = _sunMonth >= 10 ? _sunMonth : '0' + _sunMonth;
  _sunDay = _sunDay >= 10 ? _sunDay : '0' + _sunDay;


  _mealSunDay = _satYear+'-'+_satMonth+'-'+_satDay;
  _mealSaturDay = _sunYear+ '-'+_sunMonth+'-'+_sunDay;

8、注：之所以不仅获取周六，然后周日则用周六加1，就行，因为很有可能改周末不在同一个月份，比如3.31周六，4.01周日，月份不相同

9、方法体

function getWeekDay() {
  let _date = new Date();
  let _nowTime = _date.getTime();

  let _week = _date.getDay();
  let _dayLongTime = 24 * 60 * 60 * 1000;

  let _furtureSundayTimes = _nowTime + (7 - _week) * _dayLongTime;
  let _furtureSaturdayTimes = _nowTime + (6 - _week) * _dayLongTime;

  _furtureSundayTimes = new Date(_furtureSundayTimes);
  _furtureSaturdayTimes = new Date(_furtureSaturdayTimes);


  // staurday
  let _satYear = _furtureSaturdayTimes.getFullYear();
  let _satMonth = _furtureSaturdayTimes.getMonth() + 1;
  let _satDay = _furtureSaturdayTimes.getDate();
  //sunday
  let _sunYear = _furtureSundayTimes.getFullYear();
  let _sunMonth = _furtureSundayTimes.getMonth() + 1;
  let _sunDay = _furtureSundayTimes.getDate();


  _satMonth = _satMonth >= 10 ? _satMonth : '0' + _satMonth;
  _satDay = _satDay >= 10 ? _satDay : '0' + _satDay;

  _sunMonth = _sunMonth >= 10 ? _sunMonth : '0' + _sunMonth;
  _sunDay = _sunDay >= 10 ? _sunDay : '0' + _sunDay;


  _mealSunDay = _satYear+'-'+_satMonth+'-'+_satDay;
  _mealSaturDay = _sunYear+ '-'+_sunMonth+'-'+_sunDay;
  let _weekendDay = [{
    saturDay: _mealSunDay
  }, {
    sunDay: _mealSaturDay
  }]
  return _weekendDay;
}