To subtract days to a JavaScript Date object, use the setDate() method. Under that, get the current days and subtract days. JavaScript date setDate() method sets the day of the month for a specified date according to local time.
Example
You can try to run the following code to subtract 10 days from the current date.
<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)