function submitform() {
	var x = document.getElementsByTagName("input");
	for (var i = 0; i < x.length; i++) {
		if (x[i].className == "button") {
			x[i].onclick = function () {

				y = this.parentNode.parentNode.parentNode.parentNode.parentNode;

				//alert(y);
				validate(y);
			return false;
			}
		}
	}
}

function alertMessage() {
	alert (
			'De velden met een *\n'+
			'zijn verplicht.\n' +
			'Vult u ze aub in.' 
		);
	
}
function alertMessage2() {
	alert (
			'U bent vergeten \n'+
			'Dhr. of Mevr.\n' +
			'aan te geven.' 
		);
	
}
function checkEmail(address){
	var testresults = false;;
	var filter=/^([\w-]+(?:\.[\w-]+)*)@((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$/i;
	
	if (filter.test(address)){
		testresults=true;
	} else {
		testresults = false;
	}
	return (testresults);
}
function validate(form) {
	var formOk  = true;
	var message = "";
		
	///////// CONTACT ///////////////////////////
	/////////////////////////////////////////////

		if (form.id == "contact") {
			if (
			form.opmerkingen.value == "" ||
			form.voorletters.value == "" ||
			form.achternaam.value == "" ||
			form.straat.value == "" ||
			form.huisnummer.value == "" ||	
			form.postcode.value == "" ||
			form.emailAdres.value == "" ||
			form.telefoon.value == "" ||
			form.plaats.value == "" ){		
				alertMessage();
				formOk  = false;
			}
			// check radio button gender
			else if (form.geslacht[0].checked == false && 
			form.geslacht[1].checked == false){
				alertMessage2();
				formOk  = false;
			} else {
				if (!checkEmail(form.emailAdres.value)) {
					alert (
						'Het email adres \n'+
						'is niet geldig.' 
					);
					formOk  = false;
				}
			}
		}
	if (formOk){
		form.submit();
	}
		
}