Timing af events

<script type="text/javascript">
function bar() {
    alert("HeyHep");
}
function foo() {
    var elm = document.getElementById("fooBar"),
    num = elm.value;
    if (foo.timer) clearInterval(foo.timer);
    if (!(/^[0-9]+$/).test(num)) {
        alert("Du skal skrive et tal.");
        elm.focus();
        return false;
    }
    foo.timer = setInterval("bar()", parseInt(num)*1000);
}
</script>

<input id="fooBar" type="text">
<button onclick="foo()">TEST</button>

<script type="text/javascript">
function bar() {
    var thissound=document.getElementById('sound1');
    thissound.Play();
    foo.display.nodeValue = parseInt(foo.display.nodeValue)+=1;
}
function foo() {
    var elm = document.getElementById("fooBar"),
    num = elm.value;
    if (foo.timer) clearInterval(foo.timer);
    if (!foo.display) foo.display = document.getElementById("display").firstChild;
    foo.display.nodeValue = "0";
    if (!(/^[0-9]+$/).test(num)) {
        alert("Du skal skrive et tal.");
        elm.focus();
        return false;
    }
    foo.timer = setInterval("bar()", parseInt(num)*1000);
}
function fooStop() {
    if (!foo.display) return;
    clearInterval(foo.timer);
    foo.display.nodeValue = "0";
}
</script>

<span id="display">0</span>

foo.display.nodeValue = parseInt(foo.display.nodeValue)+1; // <-- Der