Comparing two dates is as simple as
var differenceInMs = dateNewer - dateOlder;
So, convert the timestamps back into Date instances
var d1 = new Date('2013-08-02T10:09:08Z'), // 10:09 to
d2 = new Date('2013-08-02T10:20:08Z'); // 10:20 is 11 mins
Get the difference
var diff = d2 - d1;
Format this as desired
if (diff > 60e3) console.log(
Math.floor(diff / 60e3), 'minutes ago'
);
else console.log(
Math.floor(diff / 1e3), 'seconds ago'
);
// 11 minutes ago