Nodejs Utililty Methods Date Add

Date.prototype.DateAdd = function(strInterval, Number) {
  var dtTmp = this;
  switch (strInterval) {
  case 's':
    return new Date(Date.parse(dtTmp) + (1000 * Number));
  case 'n':
    return new Date(Date.parse(dtTmp) + (60000 * Number));
  case 'h':
    return new Date(Date.parse(dtTmp) + (3600000 * Number));
...

Date.prototype.add=function(amount,field){
  if(amount){
    switch (field)
      case "y":
        this.setFullYear(this.getFullYear() + amount);
        break;
      case "q":
        this.setMonth(this.getMonth() + amount * 3);
...

Date.MILLI = 'ms';
Date.SECOND = 's';
Date.MINUTE = 'mi';
Date.HOUR = 'h';
Date.DAY = 'd';
Date.MONTH = 'mo';
Date.YEAR = 'y';
Date.prototype.add = function(interval, value){
  var d = this.clone();
...

Date.prototype.add = function(thisMany) {
  var self = this;
  return { minutes: function() {
    var newDate = new Date(self);
    newDate.setMinutes(self.getMinutes() + thisMany);
    return newDate; }};
};

Number.prototype.addDate=function(num){
    var date=this;
    var dates=[];
    var d=new Date(Number(date).dateFormat());
    d.setDate(d.getDate()+(num));
    dates.push(d.getFullYear());
    dates.push(Number(d.getMonth()+1).addZero());
    dates.push(Number(d.getDate()).addZero());
    var next_date=dates.join("");
...

Date.prototype.addMilliseconds = function(value)
    this.setTime(this.getTime() + value);
    return this;
};

Date.prototype.dateAdd = function (interval, number) {
    var d = new Date(this);
    var k = { 'y': 'FullYear', 'q': 'Month', 'm': 'Month', 'w': 'Date', 'd': 'Date', 'h': 'Hours', 'n': 'Minutes', 's': 'Seconds', 'ms': 'MilliSeconds' };
    var n = { 'q': 3, 'w': 7 };
    eval('d.set' + k[interval] + '(d.get' + k[interval] + '()+' + ((n[interval] || 1) * number) + ')');
    return d;

Date.prototype.dateAdd = function (interval, number) {
    var d = this;
    var k = {
        'y': 'FullYear',
        'q': 'Month',
        'm': 'Month',
        'w': 'Date',
        'd': 'Date',
        'h': 'Hours',
...

Date.prototype.dateAdd = function(size,value) {
    value = parseInt(value);
    var incr = 0;
    switch (size) {
        case 'year':
            this.setFullYear(this.getUTCFullYear()+value);
            break;
        case 'month':
            value = value + this.getUTCMonth();
...