function verif_mail(email) { 
   	var reg = /^[a-z0-9._-]+@[a-z0-9.-]{2,}[.][a-z]{2,3}$/
   	return (reg.exec(email)!=null)
}
function validResa() {
	if ( document.reservation.nom.value == '' || document.reservation.prenom.value == '' ) {
		alert('Thanks to give your first name and your last name');
		return false;
	}
	if ( document.reservation.telephone.value == '' ) {
		alert('Thanks to give your phone number');
		return false;
	}
	if ( document.reservation.mail.value == '' ) {
		alert('Thanks to give your email address');
		return false;
	}
	if ( verif_mail(document.reservation.mail.value) == false ) {
		alert('Thanks to give a valid email address');
		return false;
	}
	if ( document.reservation.datearrivee.value == '' ) {
		alert("Thanks to give your date of arrival");
		return false;
	}
	if ( document.reservation.datedepart.value == '' ) {
		alert("Thanks to give your date of departure");
		return false;
	}
	if ( document.reservation.nbpersonnes.value == 0 ) {
		alert("Thanks to give the number of persons");
		return false;
	}
	if ( document.reservation.pays.value == 0 ) {
		alert("Thanks to give your contry");
		return false;
	}
	return true;	
}