年月日三联动下拉框

< HTML >
     < HEAD >
         < title > 年月日三联动下拉框 title >
         < meta  http-equiv ='Content-Type'  content ='text/html;  charset =gb2312' >
         < meta  name ='author'  content ='http://singlepine.cnblogs.com/' >
     HEAD >
     < body >
         < form  name ="form1" >
             < select  name ="YYYY"  onchange ="YYYYDD(this.value)" >
                 < option  value =""  selected > 请选择 年 option >
             select >
             < select  name ="MM"  onchange ="MMDD(this.value)" >
                 < option  value =""  selected > 选择 月 option >
             select >
             < select  name ="DD" >
                 < option  value =""  selected > 选择 日 option >
             select >
         form >
         < script  language ="JavaScript" >
     script >
     body >
HTML >