Here's some fun I had solving something similar in node.
function formatTimeDiff(date1, date2) {
return Array(3)
.fill([3600, date1.getTime() - date2.getTime()])
.map((v, i, a) => {
a[i+1] = [a[i][0]/60, ((v[1] / (v[0] * 1000)) % 1) * (v[0] * 1000)];
return `0${Math.floor(v[1] / (v[0] * 1000))}`.slice(-2);
}).join(':');
}
const millis = 1000;
const utcEnd = new Date(1541424202 * millis);
const utcStart = new Date(1541389579 * millis);
const utcDiff = formatTimeDiff(utcEnd, utcStart);
console.log(`Dates:
Start : ${utcStart}
Stop : ${utcEnd}
Elapsed : ${utcDiff}
`);
/*
Outputs:
Dates:
Start : Mon Nov 05 2018 03:46:19 GMT+0000 (UTC)
Stop : Mon Nov 05 2018 13:23:22 GMT+0000 (UTC)
Elapsed : 09:37:02
*/
You can see it in action at https://repl.it/@GioCirque/TimeSpan-Formatting