js 日期格式转换

中国标准时间转换为特定格式时间（以2020-006-06为例）

    initDate(date){
      
      return  date.getFullYear() + "-" + (date.getMonth()> 9 ? (date.getMonth() + 1) : "0" + (date.getMonth() + 1)) + "-" +(date.getDate()> 9 ? (date.getDate()) : "0" + (date.getDate()));
    },

本周、上周的开始日期和结束日期

    getTime(n) {
      let now = new Date();
        let year = now.getFullYear();
        let month = now.getMonth() + 1;
        let day = now.getDay(); //返回星期几的某一天;
        n = day == 0 ? n + 6 : n + (day - 1)
        now.setDate(now.getDate() - n);
        let date = now.getDate();
        let s = year + "-" + (month < 10 ? ('0' + month) : month) + "-" + (date < 10 ? ('0' + date) : date);
        return s;
    },
    /***参数都是以周一为基准的***/
    //上周的开始时间
    console.log(this.getTime(7));
    //上周的结束时间
    console.log(this.getTime(1));
    //本周的开始时间
    console.log(this.getTime(0));
    //本周的结束时间
    console.log(this.getTime(-6));
    //下周的开始时间
    console.log(this.getTime(-7))
    //下周的结束时间
    console.log(this.getTime(-13))

上月开始时间和结束时间

 lastMonth(){
     let nowday = new Date();
     let year = nowday.getFullYear();
     let month = nowday.getMonth();
     if(month==0){
         month=12;
         year=year-1;
     }
     if (month < 10) {
          month = "0" + month;
     }
     let firstDayOfPreMonth = year + "-" + month + "-" + "01";
     let lastDay = new Date(year, month, 0);
     let lastDayOfPreMonth = year + "-" + month + "-" + lastDay.getDate();
     firstDayOfPreMonth = firstDayOfPreMonth.toString();
     lastDayOfPreMonth = lastDayOfPreMonth.toString();
     let value4 = [];
     value4.push(firstDayOfPreMonth); //开始时间
     value4.push(lastDayOfPreMonth); //结束时间
     return value4
  },
 // 输出结果为 ["2020-05-01", "2020-05-31"]

本月开始日期、结束日期

      CurrentMonthLast(){
        let date=new Date();
        let currentMonth=date.getMonth();
        let nextMonth=++currentMonth;
        let nextMonthFirstDay=new Date(date.getFullYear(),nextMonth,1);
        let oneDay=1000*60*60*24;
        let start = this.initDate(new Date(new Date().setDate(1)))
        let end = this.initDate(new Date(nextMonthFirstDay-oneDay))
        return  [start,end] 
      },
      //输出结果 ["2020-06-01", "2020-06-30"]