date subtraction in javascript code example

Example 1: subtracting two date objects in javacript

function findDayDifference(date1, date2) {
	// always round down
  return Math.floor((Math.abs(date2-date1))/(1000*60*60*24));
}

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)