function returnObjById( id )
{
    if (document.getElementById)
        var returnVar = document.getElementById(id);
    else if (document.all)
        var returnVar = document.all[id];
    else if (document.layers)
        var returnVar = document.layers[id];
    return returnVar;
}

function changeform()
{
	/*
	alert('mail? ' + returnObjById('info_mailpost').checked);
	alert('offerte? ' + returnObjById('offerte').checked);
	*/
	var elem,  vis;
	
	if(returnObjById('info_mailpost').checked)
	{
		elem = returnObjById('changer_1');  
		vis = elem.style;
		vis.display = 'block';
	}
	else
	{
		returnObjById('hoeinfo_1').checked = false;
		elem = returnObjById('changer_1');  
		vis = elem.style;
		vis.display = 'none';
	}
	
	if(returnObjById('offerte').checked)
	{
		elem = returnObjById('changer_4');  
		vis = elem.style;
		vis.display = 'block';
	}
	else
	{
		elem = returnObjById('changer_4');  
		vis = elem.style;
		vis.display = 'none';
	}	
	
	if(returnObjById('contacteer').checked)
	{
		elem = returnObjById('changer_3');  
		vis = elem.style;
		vis.display = 'block';
	}
	else
	{
		elem = returnObjById('changer_3');  
		vis = elem.style;
		vis.display = 'none';
	}

	if(returnObjById('hoeinfo_1').checked)
	{
		elem = returnObjById('changer_2');  
		vis = elem.style;
		vis.display = 'block';
	}
	else
	{
		elem = returnObjById('changer_2');  
		vis = elem.style;
		vis.display = 'none';
	}
}

function checkform()
{
	var errors = '';
	if(returnObjById('bedrijfsnaam').value == "") { errors += '- there was no company name \n'; }
	// if(!returnObjById('gender_1').checked && !returnObjById('gender_2').checked && !returnObjById('gender_3').checked) { errors += '- there was no title \n'; }
	if(returnObjById('naam').value == "") { errors += '- there was no name \n'; }
	if(returnObjById('email').value == "") { errors += '- there was no e-mail \n'; }
	else
	{
	atindex = returnObjById('email').value.indexOf('@');
    if (atindex<1 || atindex==(returnObjById('email').value.length-1)) { errors+='- e-mail was not correctly formed\n'; }
	else
		{
			dotindex = returnObjById('email').value.lastIndexOf('.');
			if (dotindex<atindex || dotindex==(returnObjById('email').value.length-1)) { errors+='- e-mail was not correctly formed\n'; }
		}
	}
	if(returnObjById('telefoon').value == "") { errors += '- there was no phone number \n'; }
	if(isNaN(returnObjById('telefoon').value)) { errors += '- phone number was not a number \n'; }
	
	if(returnObjById('info_mailpost').checked && returnObjById('hoeinfo_1').checked && returnObjById('adres').value == "")
	{ errors+='- to receive information at your adress, fill in an adress\n'; }

	if(returnObjById('offerte').checked && returnObjById('project').value == "")
	{ errors+='- to receive an offerte, please fill in project details\n'; }
	
	if(errors) alert('please fill the form correctly: \n'+errors);
	document.checkreturnvalue = (errors == '');
}