function toggleErrorLabel(label,state) {
	if(state == 'on') {
		document.getElementById(label).className = "errorlabel";
	}else{
		document.getElementById(label).className = "normallabel";
	}
}

function isValidEmail(str) {
   return (str.indexOf(".") > 2) && (str.indexOf("@") > 0);
}

function ValidateContactForm() {

	var form = document.getElementById('contactform');
	var error = 0;
	var errorMessage = 'For sending this form adjust the following:\n\n';
		
	if(form.naam.value == "") { 
		errorMessage += '- Name is missing\n';
		error = 1;
		toggleErrorLabel('label_naam','on');
	}else{
		toggleErrorLabel('label_naam');
	}
	if(form.email.value == "") {
		errorMessage += '- Emailaddress is missing\n';
		error = 1;
		toggleErrorLabel('label_email','on');
	}else{
		if(isValidEmail(form.email.value)) {
			toggleErrorLabel('label_email');
		}else{
			errorMessage += '- Emailaddress is wrong\n';
			error = 1;
			toggleErrorLabel('label_email','on');	
		}	
	}
	if(form.bericht.value == "") { 
		errorMessage += '- Message is missing\n';
		error = 1; 	
		toggleErrorLabel('label_bericht','on');
	}else{
		toggleErrorLabel('label_bericht');
	}
	
	if(error){
		alert(errorMessage);
		return false; 
	}else{
		return true;
	}
}

function clearDefault(el)
{
  if (el.defaultValue == el.value) el.value = '';
}

function setDefault(el)
{
  if (el.value == '') el.value = el.defaultValue;
}