function check()
{

    if(document.getElementById("idVeldNaam").value == ""){
        document.getElementById("naamVerplicht").style.visibility="visible";
        return false;
    }else
        document.getElementById("naamVerplicht").style.visibility="hidden";
    if(document.getElementById("idVeldUsername").value == ""){
        document.getElementById("userNameVerplicht").style.visibility="visible";
        return false;
    }else
        document.getElementById("userNameVerplicht").style.visibility="hidden";

    if(document.getElementById("idVeldPw").value == ""){
        document.getElementById("pwVerplicht").style.visibility="visible";
        return false;
    }else
        document.getElementById("pwVerplicht").style.visibility="hidden";
    

    return true;


}