How to reload a webpage after a specific time without refresh the page(address bar will not be refresh) by jquery/ajax

How to reload a webpage after a specific time without refresh the
page(address bar will not be refresh) by jquery/ajax

It will be implemented in PHP. Now it is implemented by the following way.
function timedRefresh(timeoutPeriod) {
setTimeout("location.reload(true);",timeoutPeriod);
}
Now it refreshed the addres bar...but I don't want to refresh the address
bar.....