MktoForms2 :: auto-submit

HTML

<script src="//app-sj01.marketo.com/js/forms2/js/forms2.min.js"></script>
<form id="mktoForm_120"></form>
<script>MktoForms2.loadForm("//app-sj01.marketo.com", "410-XOR-673", 621,
    function(form) 
    {
        form.submit();
        form.onSuccess(function(form){
            document.body.insertAdjacentHTML('afterend','Form submitted!');
            return false;
        });
    });
</script>

CSS

.mktoForm {
    display: none;
}