The JS implementation calculates the age based on the date of birth


<script language=javascript>  
  function   ages(str)  
  {  
        var   r   =   str.match(/^(d{1,4})(-|/)(d{1,2})2(d{1,2})$/);    
        if(r==null)return   false;    
        var   d=   new   Date(r[1],   r[3]-1,   r[4]);    
        if   (d.getFullYear()==r[1]&&(d.getMonth()+1)==r[3]&&d.getDate()==r[4])  
        {  
              var   Y   =   new   Date().getFullYear();  
              return(" age    =   "+   (Y-r[1])   +"    One full year of life ");  
        }  
        return(" Wrong date format! ");  
  }  
  alert(ages("1980-03-22"));  
  alert(ages("2002-01-31"));  
  alert(ages("2002-01-41"));  
  </script>