获取当前日期是第几周，以及本周的星期一是几号

 1 var dateNow = new Date();
 2 var year = dateNow.getFullYear();
 3 var month = dateNow.getMonth() + 1;
 4 var day = dateNow.getDate();
 5 var week = getYearWeek(year, month, day);//今天是第几周
 6 var WeekFirstDay = new Date(dateNow - (dateNow.getDay() - 1) * 86400000);
 7 var day1 = (WeekFirstDay.getMonth() + 1) + '-' + WeekFirstDay.getDate();//本周星期一的日期
 8 WeekFirstDay.setDate(WeekFirstDay.getDate() + 7);
 9 var day2 = (WeekFirstDay.getMonth() + 1) + '-' + WeekFirstDay.getDate();//下周星期二的日期
10 
11 function getYearWeek(year, month, date) {
12     /*  
13         dateNow是当前日期 
14         dateFirst是当年第一天  
15         dataNumber是当前日期是今年第多少天  
16         用dataNumber + 当前年的第一天的周差距的和在除以7就是本年第几周  
17     */
18     let dateNow = new Date(year, parseInt(month) - 1, date);
19     let dateFirst = new Date(year, 0, 1);
20     let dataNumber = Math.round((dateNow.valueOf() - dateFirst.valueOf()) / 86400000);
21     return Math.ceil((dataNumber + ((dateFirst.getDay() + 1) - 1)) / 7);
22 };