moment.js has some really nice convenience methods to manipulate date objects
The .subtract method, allows you to subtract a certain amount of time units from a date, by providing the amount and a timeunit string.
var now = new Date();
// Sun Jan 22 2017 17:12:18 GMT+0200 ...
var olderDate = moment(now).subtract(3, 'minutes').toDate();
// Sun Jan 22 2017 17:09:18 GMT+0200 ...