根据周，从一个日期范围内筛选

// 筛选
let startDate = new Date('2021-08-20'); // 筛选的开始时间
let endDate = new Date('2021-09-20'); // 结束时间
let s_time = startDate.getTime();
let e_time = endDate.getTime();
let time_diff = e_time - s_time;
var d_arr = [];
for(var i=0; i<= time_diff; i += 86400000){
    let __date = new Date(s_time+i);
    let year = __date.getFullYear();
    let month = __date.getMonth()+1;
    let day = __date.getDate();
    let date = year+ "-" +month+ "-" +day;
    d_arr.push(date)
}
var weekDay = [1,2,3] // 要筛选的周
let dateArray = [] // 最后筛选出来的日期
d_arr.forEach(it => {
    weekDay.forEach(el => {
      if (new Date(it).getDay() == el) {   
        dateArray.push(it)
      }
    })
})

console.log(dateArray)