<script type="text/javascript">
              //日期，在原有日期基礎上，增加days天數，默認增加1天
              function addDate(date, days) {
                  if(days == undefined || days == ‘‘) {
                      days = 1;
                  }
                  var date = new Date(date);
                  date.setDate(date.getDate() + days);
                  var month = date.getMonth() + 1;
                var day = date.getDate();
                 var mm = "‘" + month + "‘";
                 var dd = "‘" + day + "‘";
                 
                 //單位數前面加0
                 if(mm.length == 3) {
                     month = "0" + month;
                 }
                 if(dd.length == 3) {
                     day = "0" + day;
                 }
 
                 var time = date.getFullYear() + "-" + month + "-" + day
                 return time;
             }
 
             var addTime = addDate("2017-07-24", 2);
             console.log(addTime);//2017-07-26
         </script>
轉自：https://www.cnblogs.com/wush-1215/p/7230397.html
 

【日期處理】在日期加上幾天，返回日期。