Idea: Solve single-use button problem using cache busting headers

[shark0der]

By sending the Cache-control: private, max-age=0, no-cache and Expires: Thursday, 1 January 1970 00:00:00 GMT we can force the browser to send requests while reusing the background image (less state tracking).

[kkuchta]

Interesting... we may not actually need that.

So, the root issue is that if there's a single <div id='A'> and we've got:

#A:active {
  background-image: url('/img/a.jpg');
}

then on the first click, a.jpg gets loaded and on subsequent clicks, it doesn't get loaded again. I kinda assumed that if we put multiple elements with the same background image on the page, we'd only get one request. It looks like that might not be the case.

#A:active {
  background-image: url('/img/a.jpg');
}
#B:active {
  background-image: url('/img/a.jpg');
}

^ given that, even with no interesting cache headers at all, chrome will load img/a.jpg twice, once on each button click. And if we're replacing the whole DOM every button click anyway, you're right: we really only need the image url to include just the single letter being used (and probably the client_id). No more url('/img/helloworld-and-all-previous-messages-a.') XD