2020-05-30 js获取上周，本周，下周日期

<script>

         //获取时间段 （一周的时间 七天）

               var formatDate = function(date) {

                 var year = date.getFullYear(); //年

                 var month = date.getMonth() + 1; //月

                 var day = date.getDate(); //日;

                 return year + "-" + month + "-" + day;

               };

               var addDate = function(date, n) {

                 date.setDate(date.getDate() + n);

                 return date;

               };

               var setDate = function(date) {

                var week = date.getDay() - 1;

                 date = addDate(date, week * -1);

                 var weekList = [];

                 for (var i = 0; i < 7; i++) {

                   weekList[i] = formatDate(i == 0 ? date : addDate(date, 1));

                 }

                 return weekList;

               };

               var lastWeek = setDate(addDate(new Date(),-7)); //上周

               var thisWeek = setDate(addDate(new Date(), 0)); //本周

               var nextWeek = setDate(addDate(new Date(), +7)); //下周

               var today = formatDate(new Date()); //今日日期

      </script>