function f_date(obj){
var s;
var dtoday = new Date()
s = '' + obj.value;
if (s == ''){return true;}
var reg2 = /^\d{1,2}(\-|\/|\.)\d{1,2}\1\d{4}$/;
var reg3 = /^\d{1,2}(\-|\/|\.)\d{1,2}\1\d{2}$/;
var reg1 = /^\d{1,2}(\-|\/|\.)\d{1,2}$/;
if (!reg2.test(s)){
  if (reg1.test(s)){
     obj.value = s + '/' + dtoday.getFullYear();
     s = '' + obj.value;
  } else {
    if (reg3.test(s)){
    n = s.length;
    s_year = s.substr(n-2,2);
    if ((s_year - 1 + 1) > 50){s_cent = '19'} else {s_cent = '20'}
    s = s.substr(0,n-2) + s_cent + s_year;
    obj.value = s;
    
    } else {
    alert('Invalid Date');
    obj.focus();
    obj.value = '';
    return false;
    }
  }
}
var parts = s.split(RegExp.$1); 
dd = parts[1];mm = parts[0];yy=parts[2];
var dt = new Date(parseFloat(yy), parseFloat(mm)-1, parseFloat(dd), 0, 0, 0, 0);
   if (parseFloat(dd) != dt.getDate()) {
   alert('Invalid Date');
    obj.focus();
    obj.value = '';
    return false; }
   if (parseFloat(mm)-1 != dt.getMonth()) { 
   alert('Invalid Date');
    obj.focus()
    obj.value = '';
    return false; 
    }
return true;
}