Here you can find the source of addMonth()
Date.prototype.addMonth = function () { var date = new Date(this.valueOf()); date.setMonth(date.getMonth() + 1);//from ww w . jav a 2 s . c om return date; };
Date.prototype.addMonth = function(){
this.setMonth(this.getMonth() + 1);
};
Date.prototype.addMonth = function addMonth () {
this.setDate(1);
this.setHours(0);
this.setMinutes(0);
this.setSeconds(0);
this.setMonth(this.getMonth() + 1);
};
Date.prototype.addMonths = function(m) { var d = this.getDate(); this.setMonth(this.getMonth() + m); if (this.getDate() < d) this.setDate(0); };
Date.prototype.addMonths = function(months){ return new Date(this.getTime() + months*this.getDaysInMonthOfYear()*24*60*60*1000);
Date.prototype.addMonths = function(months) { var n = this.getDate(); this.setDate(1); this.setMonth(this.getMonth() + months); this.setDate(Math.min(n, this.getDaysInMonth())); return this; };