function calcAge(bdag, bmaand, bjaar){
 if(bdag=='noval' || bmaand=='noval'){
 yearsOld = 'noval';
 }
 else{
 dDate = parseInt(bdag,10);
 dMonth = parseInt(bmaand,10);
 dYear = parseInt(bjaar,10);
 if (ageForm.gebmaand.selectedIndex<1) return 'novalMonth';
 if (ageForm.gebdag.selectedIndex<1) return 'novalDate';
 if (isNaN(dYear) || (bjaar.length!=4) || ((dYear + "").length!=bjaar.length)) return 'novalYear';
 curDate = new Date();
 yearsOld = curDate.getFullYear() - dYear;
 monthsOld = (curDate.getMonth() + 1) - dMonth;
 daysOld = curDate.getDate() - dDate;
 if ((monthsOld < 0) || (monthsOld == 0 && daysOld < 0)) yearsOld --;
 if (yearsOld < 0) yearsOld = 'novalYear';
} 
 return yearsOld;
}

function Check()
{
 ageForm = document.form1;
 bmaand = ageForm.gebmaand.options[ageForm.gebmaand.selectedIndex].value;
 bdag = ageForm.gebdag.value;
 //bjaar = "19" + ageForm.gebjaar.value;
 bjaar = ageForm.gebjaar.value;
 
 minage = ageForm.ageok.value;
 enterage = calcAge(bdag, bmaand, bjaar);
 
 if(enterage=='noval' || enterage=='novalYear' || enterage=='novalMonth' || enterage=='novalDate' || ageForm.ageok.value=='noval')
   {
    if(enterage=='noval' || ageForm.ageok.value=='noval'){
    alert("Alle velden verplicht invullen");
    }    
   }   
   else 
   { 
    if (enterage >=minage){
    document.location.href="http://www.themillerway.nl/horecaof.php";
    }
    else if (enterage < minage && enterage > 0){
    document.location.href="javascript:alert('Sorry, om deze site te bezoeken moet je minimaal 18 jaar oud zijn.')";
    return;
     }
   }
 }