To add seconds to a JavaScript Date object, use the setSeconds() method. Under that, get the current seconds and add 10 seconds to it. JavaScript date setSeconds() method sets the seconds for a specified date according to local time.
You can try to run the following code to add 10 seconds to date.
Example
<html>
<head>
<title>JavaScript setSeconds Method</title>
</head>
<body>
<script>
var dt = new Date("December 30, 2017 11:20:25");
dt.setSeconds( dt.getSeconds() + 10 );
document.write( dt );
</script>
</body>
</html>Output
Sat Dec 30 2017 11:20:35 GMT+0530 (India Standard Time)