function DateAdd( interval, number, date )
{
 var wDate = new Date( date );
 var time  = 0;

 try {
  switch ( interval ) {
  case "yyyy":
   wDate = new Date( wDate.getFullYear()+number, wDate.getMonth(), wDate.getDate(), wDate.getHours(), wDate.getMinutes(), wDate.getSeconds() );
   break;
  case "q":
   wDate = new Date( wDate.getFullYear(), wDate.getMonth()+number*3, wDate.getDate(), wDate.getHours(), wDate.getMinutes(), wDate.getSeconds() );
   break;
  case "m":
   wDate = new Date( wDate.getFullYear(), wDate.getMonth()+number, wDate.getDate(), wDate.getHours(), wDate.getMinutes(), wDate.getSeconds() );
   var compDate = new Date( wDate.getFullYear(), wDate.getMonth()+number, 1, wDate.getHours(), wDate.getMinutes(), wDate.getSeconds() );
   if ( wDate.getMonth() != compDate.getMonth() ) {
    wDate.setDate( 1 );
    wDate.setTime( wDate.getTime() - (24*60*60*1000) );
   }
   break;
  case "y":
  case "d":
  case "w":
   wDate = new Date( wDate.getFullYear(), wDate.getMonth(), wDate.getDate()+number, wDate.getHours(), wDate.getMinutes(), wDate.getSeconds() );
   break;
  case "ww":
   wDate = new Date( wDate.getFullYear(), wDate.getMonth(), wDate.getDate()+number*7, wDate.getHours(), wDate.getMinutes(), wDate.getSeconds() );
   break;
  case "h":
   wDate = new Date( wDate.getFullYear(), wDate.getMonth(), wDate.getDate(), wDate.getHours()+number, wDate.getMinutes(), wDate.getSeconds() );
   break;
  case "n":
   wDate = new Date( wDate.getFullYear(), wDate.getMonth(), wDate.getDate(), wDate.getHours(), wDate.getMinutes()+number, wDate.getSeconds() );
   break;
  case "s":
   wDate = new Date( wDate.getFullYear(), wDate.getMonth(), wDate.getDate(), wDate.getHours(), wDate.getMinutes(), wDate.getSeconds()+number );
   break;
  default:
  }
 } catch ( e ) {
  return date;
 }

 wDate.setTime( wDate.getTime() + time );

 return wDate;
}