jsは今日と過去の日付を取得します.

function GetDateStr(AddDayCount) { 
    var dd = new Date(); 
    dd.setDate(dd.getDate()+AddDayCount);//  AddDayCount      
    var y = dd.getFullYear(); 
    var m = dd.getMonth()+1;//          
    var d = dd.getDate(); 
    //    
    if(m < 10){
      m = "0" + m;
    }else{
      m = m;
    }
    //    n     
    if(d < 10){//    <10
      d = "0" + d;
    }else{
      d = d;
    }
    return y+"-"+m+"-"+d; 
  } 

function GetMonthStr(AddMonthCount) { 
    var dd = new Date(); 
    dd.setMonth(dd.getMonth()+AddMonthCount);//  AddMonthCount      
    var y = dd.getFullYear(); 
    var m = dd.getMonth()+1;//          
    var d = dd.getDate(); 
    //    
    if(m < 10){
      m = "0" + m;
    }else{
      m = m;
    }
    //    n     
    if(d < 10){//    <10
      d = "0" + d;
    }else{
      d = d;
    }
    return y+"-"+m+"-"+d; 
  } 

function GetYearStr(AddYearCount) { 
    var dd = new Date(); 
    dd.setYear(dd.getFullYear()+AddYearCount);//  AddMonthCount      
    var y = dd.getFullYear(); 
    var m = dd.getMonth()+1;//          
    var d = dd.getDate(); 
    //    
    if(m < 10){
      m = "0" + m;
    }else{
      m = m;
    }
    //    n     
    if(d < 10){//    <10
      d = "0" + d;
    }else{
      d = d;
    }
    return y+"-"+m+"-"+d; 
  }