function checkVelden(obj){
	velden = obj.getElementsByTagName("input");
	for(i =0; i < i.length; i++){
		if(velden[i].className.toString().indexOf("required") != -1){
			// check here the value of a normal field
		} else if(velden[i].className.toString().indexOf("required_email") != -1){
			// check here the email
		} else if(velden[i].className.toString().indexOf("required_password") != -1){
			// check here the both passwords
		}
	}
}