var aantalheaders = 5;

function randomheader() {
    var randomnumber = Math.floor(Math.random() * (aantalheaders));
    randomnumber += 1;
    if (randomnumber < 10) randomnumber = '0' + randomnumber;
    document.getElementById('header').style.backgroundImage = "url(media/hdr_bg" + randomnumber + ".jpg)";
}

function submitwait() {

    document.getElementById('hetform').style.display = 'none';
    document.getElementById('verzenden').style.display = 'block';
    document.getElementById('verzenden').innerHTML = "Bezig met verzenden....";
    setTimeout(" document.getElementById('verzenden').innerHTML = 'Uw bericht is verzonden'", 7000);

}