How to detect when XHR returns a cached resource?

Question

I\'m wondering if there is a way how to detect when a response is returned from a local cache? Is it possible?

The solution should be general and work for unconditi

Answer 1

Check to see if the status code returned is 304 (not modified) in the onreadystatechange function. Something along the lines of:

xmlhttp.onreadystatechange=function()
{
  if (xmlhttp.readyState==4 && xmlhttp.status==304)
    {
      alert("Cached");
    }
}