subtract time from date - moment js

Question

I have for instance this datetime:

01:20:00 06-26-2014

and I want to subtract a time like this:

00:03:15

Answer 1

I use moment.js http://momentjs.com/

var start = moment(StartTimeString).toDate().getTime();
var end = moment(EndTimeString).toDate().getTime();
var timespan = end - start;
var duration = moment(timespan);
var output = duration.format("YYYY-MM-DDTHH:mm:ss");