javascript banners freezes on first banner

<script>
    var links = ["http://site","http://site"];
    var images = ["/uploads/ad1.png","/uploads/ad2.png"];
    var i = 0;
    var renew = setInterval(function(){
        if(links.length == i){
            i = 0;
        }
        else {
            document.getElementById("bannerImage").src = images[i];
            document.getElementById("bannerLink").href = links[i];
            i++;

        }
    },500);
</script>

<div class="container"><div class="text-center"><a id="bannerLink" href="http://site" onclick="void window.open(this.href); return false;"><img id="bannerImage" src="/uploads/ad1.png" width="320" height="120" alt="some text"></a></div></div>