How to get seconds since epoch in JavaScript?

Given a date, we have to find the number of seconds since the epoch (i.e. 1 January 1970, 00:00:00 UTC ). The getTime() method in the JavaScript returns the number of milliseconds since January 1, 1970, or epoch. If we divide these milliseconds by 1000 and then integer part will give us the number of seconds since epoch.

Example:

Input: Date = 27-04-2020, 11:55:55
Output: Seconds since epoch - 1587968755

Syntax:

new Date(year, month, day, hours, minutes, seconds, milliseconds)

Example:

<script type="text/javascript">
    function seconds_since_epoch(d){
        return Math.floor( d / 1000 );
    }

    // Driver Code
    var d = new Date(2020, 4, 29, 22, 00, 00, 00);
    var sec = seconds_since_epoch(d);
    document.write("Date " + d + " has "
                   + sec+ " seconds till epoch.");
</script>

Output:

Date Fri May 29 2020 22:00:00 GMT+0530 (India Standard Time) 
has 1590769800 seconds till epoch.