subtract current date from another date in javascript code example

Example 1: javascript subtract days from date

var myCurrentDate=new Date();
var myPastDate=new Date(myCurrentDate);
    myPastDate.setDate(myPastDate.getDate() - 8);//myPastDate is now 8 days in the past

Example 2: how to substract date object javascript

Example
<html>
   <head>
      <title>JavaScript setDate Method</title>
   </head>
   <body>
      <script>
         var dt = new Date("December 30, 2017 11:20:25");
         dt.setDate( dt.getDate() - 10 );
         document.write( dt );
      </script>
   </body>
</html>
Output
Wed Dec 20 2017 11:20:25 GMT+0530 (India Standard Time)