function checkMailafriend(myForm)
{
	var result = true;
	
	if (myForm.o_naam.value == "")
	{
		alert("Voer aub zijn / haar naam in");
		myForm.o_naam.focus();
		result = false;
	}
	else if (myForm.naam.value == "")
	{
		alert("Voer aub uw naam in");
		myForm.naam.focus();
		result = false;
	}
	else if (!isEmailAddr(myForm.o_email.value))
	{
		alert("Voer aub een geldig email adres van hem / haar in");
		myForm.o_email.focus();
		result = false;
	}
	else if (!isEmailAddr(myForm.email.value))
	{
		alert("Voer aub een geldig email van u in");
		myForm.email.focus();
		result = false;
	}
	
	return result;
}

function validRequired(formField,message)
{
	var result = true;
	
	if (formField.value == "")
	{
		alert(message);
		formField.focus();
		result = false;
	}
	
	return result;
}

function validCheckbox(formField,message)
{
	var result = true;
	
	if (!formField.checked)
	{
		alert(message);
		formField.focus();
		result = false;
	}
	
	return result;
}

function checkAllRadios(form) 
{
 var el = formField.elements;
 for(var i = 0 ; i < el.length ; ++i) {
	if(el[i].type == "radio") {
		var radiogroup = el[el[i].name]; // get the whole set of radio buttons.
		var itemchecked = false;
		for(var j = 0 ; j < radiogroup.length ; ++j) {
			if(radiogroup[j].checked) {
				itemchecked = true;
				break;
			}
		}
		if(!itemchecked) { 
			alert("U heeft niets ingevoerd bij " + el[i].name + ".");
			return false;
		}
	}
}
return true;
}

function checkRadio(formField, RadioName, message) 
{
 var el = formField.elements(RadioName);
 for(var i = 0 ; i < el.length ; ++i) {
	if(el[i].type == "radio") {
		var radiogroup = el[el[i].name]; // get the whole set of radio buttons of specified name.
		var itemchecked = false;
		for(var j = 0 ; j < radiogroup.length ; ++j) {
			if(radiogroup[j].checked) {
				itemchecked = true;
				break;
			}
		}
		if(!itemchecked) { 
			alert(message);
			return false;
		}
	}
}
return true;
}

function allDigits(str)
{
	return inValidCharSet(str,"0123456789");
}

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,message,required)
{
	var result = true;
	
	if (required && !validRequired(formField,message))
		result = false;

	if (result && ((formField.value.length < 3) || !isEmailAddr(formField.value)) )
	{
		alert("Dit is geen geldig e-mail adres...");
		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;
}

function validNum(formField,message,required)
{
	var result = true;

	if (required && !validRequired(formField,message))
		result = false;
  
 	if (result)
 	{
 		if (!allDigits(formField.value))
 		{
 			alert(message);
			formField.focus();		
			result = false;
		}
	} 
	
	return result;
}


function validInt(formField,message,required)
{
	var result = true;

	if (required && !validRequired(formField,message))
		result = false;
  
 	if (result)
 	{
 		var num = parseInt(formField.value);
 		if (isNaN(num))
 		{
 			alert(message);
			formField.focus();		
			result = false;
		}
	} 
	
	return result;
}


function validDate(formField,message,required)
{
	var result = true;

	if (required && !validRequired(formField,message))
		result = false;
  
 	if (result)
 	{
 		var elems = formField.value.split("-");
 		
 		result = (elems.length == 3); // should be three components
 		
 		if (result)
 		{
  			var day = parseInt(elems[0]);
 			var month = parseInt(elems[1]);
			var year = parseInt(elems[2]);
			result = allDigits(elems[1]) && (month > 0) && (month < 13) &&
					 allDigits(elems[0]) && (day > 0) && (day < 32) &&
					 allDigits(elems[2]) && ((elems[2].length == 2) || (elems[2].length == 4));
 		}
 		
  		if (!result)
 		{
 			alert(message);
			formField.focus();		
		}
	} 
	
	return result;
}