There are times when we don’t have control over pages being cached ( IE Provides the ability of not Caching your pages). The down side of this is, when a request for a page has been made more than once and the data expected is not the same every time, The browser returns the same data as the first time.
To avoid this, add the following random key as a query string to the URL, this ensures that the URI is unique on every request. So even though caching occurs, the Browser treats each request as a new one.
var url = "status.xml?RandomKey=" + Math.random() * Date.parse(new Date());