moment().duration().clone();

npm install moment

const moment = require('moment'); 
  
let durationOne = moment.duration(9, 'months'); 
console.log( 
    "durationOne data:", 
    durationOne.toISOString() 
); 
  
let durationTwo = durationOne.clone(); 
console.log( 
    "durationTwo data:", durationTwo.toISOString() 
);

durationOne data: P9M
durationTwo data: P9M

const moment = require('moment'); 
  
let durationA =  
    moment.duration({months: 10, days: 7, hours: 3}); 
console.log( 
    "durationA data:", durationA.toISOString() 
); 
  
let durationB = durationA.clone(); 
console.log( 
    "durationB data:", durationB.toISOString() 
);

durationA data: P10M7DT3H
durationB data: P10M7DT3H
durationC data: P10M7DT3H