Here you can find the source of addMinute()
Date.prototype.addMinute = function(){
this.setTime(this.getTime() + (60 * 1000));
};
Date.prototype.addMinute = function addMinute () {
this.setMinutes(this.getMinutes() + 1);
this.setSeconds(0);
};
function addMinutes(date, minutes) { return new Date(date.getTime() + minutes*60000); };
Date.prototype.addMinutes = function(hours) { this.setMinutes(this.getMinutes() + hours); return this; };
Date.prototype.addMinutes = function(m) { this.setTime(this.getTime() + (m*60*1000)); return this;