To convert time in seconds, firstly get the current time. Then, multiply the hours to 3600 and minutes to 60; rest you can see below −
(hours*3600) + (min*60) + sec
Example
You can try to run the following code to get the current time in seconds −
<html>
<head>
<title>JavaScript Get Seconds</title>
</head>
<body>
<script>
var dt = new Date();
var sec = dt.getSeconds();
document.write("Seconds: " + sec);
var min = dt.getMinutes();
document.write("<br>Minutes: " + min);
var hrs = dt.getHours();
document.write("<br>Hours: " + hrs);
var total_seconds = (hrs*3600) + (min*60) + sec;
document.write("<br>Total seconds: " + total_seconds) ;
</script>
</body>
</html>Output
Seconds: 35 Minutes: 37 Hours: 9 Total seconds: 34655