function gId(idName) {
if (!document.getElementById(idName)) { return false; }
return document.getElementById(idName);
}
function load_iframe(){
if(gId('plz') && gId('jahrgang') && gId('iframearea')){
//document.getElementById('iframearea').innerHTML = '';
document.getElementById('iframearea').innerHTML = '';
} else if(gId('iframearea')) {
document.getElementById('iframearea').innerHTML = '';
}
}