moment().duration().seconds();

npm install moment

const moment = require('moment'); 
  
let durationOne = moment.duration(50, 'seconds'); 
let durationTwo = moment.duration(368, 'seconds'); 
  
// This returns 50 as the number of 
// seconds is less than a whole minute (60 seconds) 
console.log( 
    "durationOne seconds is:", durationOne.seconds() 
) 
  
// This returns 8 as the duration has 
// 6 complete minutes (360 seconds),  
// and therefore returns the value of 
// seconds of the next minute (next 8 seconds) 
console.log( 
    "durationTwo seconds is:", durationTwo.seconds() 
)

durationOne seconds is: 50
durationTwo seconds is: 8

const moment = require('moment'); 
  
let durationA =  
    moment.duration(36500, 'milliseconds'); 
let durationB =  
    moment.duration(3858, 'milliseconds'); 
  
// The asSeconds() method will return the 
// length of the duration in seconds 
console.log( 
    "Length of durationA in seconds is:", durationA.asSeconds() 
) 
  
// It returns the number of complete seconds 
console.log("durationA seconds is:", durationA.seconds()) 
  
console.log( 
    "Length of durationB in seconds is:", durationB.asSeconds() 
) 
  
// It returns the number of complete seconds 
console.log("durationB seconds is:", durationB.seconds())

Length of durationA in seconds is: 36.5
durationA seconds is: 36
Length of durationB in seconds is: 3.858
durationB seconds is: 3