Question

I am using a jQuery preloader for my images and I was wondering if it is possible to check if a page is already cached in a users browser before running the loader, is this possible?

The plugin runs on dom load with a function

$(document).ready(function () {
    $("body").queryLoader2();
});

Could I write something like:

$(document).ready(function () {
    if (!page_cached) {
        $("body").queryLoader2();
    }
    else {
        //do nothing
        return false;
    }
});

Appreciate your responses, thanks.

Answer 1

You could do a head request via ajax and if it returns 304 instead of 200, it would mean its there in the cache. Something in javascript would be like:

function isInCache(url)
{
  var http = new XMLHttpRequest();
  http.open('HEAD', url, false);
  http.send();
  return http.status;
}
//then
$(document).ready(function () {
    if (isInCache(your_page_url) != "304") {
        $("body").queryLoader2();
    }
    else {
        //do nothing
        return false;
    }
});

Hope it helps