javascript call php interval

I need a solution for using javascript to call a php file to refresh some part of a page with certain interval.

I googled the following code, by do not know how to make it work.

<script>
setpage();
 
function pageincrement()
{
page = page+1;
if(page>5)
{
page=1
}
 
setpage();
}
 
function setpage()
{
var url = "topicbanner.php";
setTimeout("pageincrement()", 5000);
if(mouseOnDiv ==1) return;
var pars ='cmd=pageload&htmlpage='+page;
var myAjax = new Ajax.Request(url, {method: 'get', parameters: pars, onComplete: showResponse});
}
 
function showResponse(serverResponse)
{
var response = serverResponse.responseText;
 
$('quiz_list').innerHTML = response;
}
</script>

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