Hi Sourabh,

check the below code.

getTimeDiff();  

  function getTimeDiff(){  

  var startDate = current.u_start_date.getGlideObject();  

  var endDate = current.u_end_date.getGlideObject();  

  current.u_duration = gs.dateDiff(startDate.getDisplayValueInternal(),endDate.getDisplayValueInternal(),false);  

  }

Thanks,

Harshvardhan