JS Cycle And Count Img Changes

<html>
<head>
<script>
var counterrep=0;
var banners=['ffff.png','jjj.png','ff.png'];
var counter=0;
function run(){
setInterval(cycle,2000);
}
function cycle(){
counter++;
if(counter==banners.length) {
counter=0;
}
document.getElementById("img").src=banners[counter];
counterrep++;
document.body.innerHTML=(document.body.innerHTML)+'<br>Image #:'+counterrep+'<br>';
}
</script>
<body onload="script:run();">
<img id="img" style="width:500;height:500">
</body>
</html>