function validRequired(formField,fieldLabel)
{
	var result = true;
	if (formField.value == "")
	{
		alert("Vul je " + fieldLabel +" in.");
		formField.focus();
		result = false;
	}
	return result;
}

function validNum(formField,fieldLabel)
{
	var result = true;
 	if (!inValidCharSet(formField.value,"-0123456789"))
 	{
 		alert("Geef "  + fieldLabel +" in cijfers.");
		formField.focus();
		result = false;
	}
	return result;
}

function inValidCharSet(str,charset)
{
	var result = true;
	// Note: doesn't use regular expressions to avoid early Mac browser bugs
	for (var i=0;i<str.length;i++)
		if (charset.indexOf(str.substr(i,1))<0)
		{
			result = false;
			break;
		}
	return result;
}

function validEmail(formField)
{
	var result = true;
	if(formField.value =="")
	{
	}
	else
	{
		if ((formField.value.length < 3) || !isEmailAddr(formField.value))
		{
			alert("Geef een volledig emailadres van de vorm: jouwnaam@jouwdomein.nl");
			formField.focus();
			result = false;
		}
	}

  return result;
}

function isEmailAddr(email)
{
  var result = false;
  var theStr = new String(email);
  var index = theStr.indexOf("@");
  if (index > 0)
  {
    var pindex = theStr.indexOf(".",index);
    if ((pindex > index+1) && (theStr.length > pindex+1))
	result = true;
  }
  return result;
}

['straat'];
['postcode'];

function validateForm(theForm)
{
	if (!validRequired(theForm.naam,"naam"))
		return false;

	if (!validRequired(theForm.straat,"straat"))
		return false;

	if (!validRequired(theForm.postcode,"postcode"))
		return false;

	if (!validRequired(theForm.telefoonnummer,"telefoonnummer"))
		return false;

	if (!validNum(theForm.telefoonnummer,"telefoonnummer"))
		return false;

	if (!validEmail(theForm.email_adres,"emailadres"))
		return false;

	return true;
}