function isInt(myNum) {
         // get the modulus: if it's 0, then it's an integer
         var myMod = myNum % 1;

         if (myMod == 0) {
                 return true;
         } else {
                 return false;
         }
}

function getYears(){
var Now = new Date();
Annee = Now.getFullYear();

mainform.adYear.length=1;

for (i=0;i<=6;i++){
NewOpt =  new Option;
NewOpt.value = Annee;
NewOpt.text = Annee;
Annee -= 1;
mainform.adYear.options[i+1] =  NewOpt;}
}

function getListDays(){
Jour = mainform.adDay.value;
Mois = mainform.adMonth.value;
Annee = mainform.adYear.value;
if (Annee == "") {Bis = false;}
else {Bis = isInt(Annee/4);}
switch (Mois) {
case "2":
if (Bis == true) {nbDays=29;}
else {nbDays=28;}
break;
case "4":
nbDays=30;
break;
case "6":
nbDays=30;
break;
case "9":
nbDays=30;
break;
case "11":
nbDays=30;
break;
default:
nbDays=31;
break;}
mainform.adDay.length=1;
for (i=1; i<=nbDays; i++){
NewOpt =  new Option;
NewOpt.value = i;
NewOpt.text = i;
if (i == Jour){NewOpt.selected = true;} 
mainform.adDay.options[i] =  NewOpt;}
}