calculate difference in time between hour minute and sec code example

Example: calculate total time from start and end datetime

var date1 = new Date('2019-02-27T23:34:25');
var date2 = new Date('2019-02-28T15:55:38');
var ElapsedSeconds = (date2 - date1) / 1000;
// var ElapsedHours = ElapsedSeconds / 3600;