reservationForm.onsubmit = function(){
let index = 0;
customSelect.classList.remove('empty');
for(let i = 0;i<reservationFormReq.length;i++){
reservationFormReq[i].classList.remove('error');
if(reservationFormReq[i].value === ''){
reservationFormReq[i].classList.add('error');
index++;
}
}
if(index === 0){
alert('succses');
}
}