Preventing iframe caching in browser

I have been able to work around this bug by setting a unique name attribute on the iframe - for whatever reason, this seems to bust the cache. You can use whatever dynamic data you have as the name attribute - or simply the current ms or ns time in whatever templating language you're using. This is a nicer solution than those above because it does not directly require JS.

In my particular case, the iframe is being built via JS (but you could do the same via PHP, Ruby, whatever), so I simply use Date.now():

return '<iframe src="' + src + '" name="' + Date.now() + '" />';

This fixes the bug in my testing; probably because the window.name in the inner window changes.

As you said, the issue here is not iframe content caching, but iframe url caching.

As of September 2018, it seems the issue still occurs in Chrome but not in Firefox.

I've tried many things (adding a changing GET parameter, clearing the iframe url in onbeforeunload, detecting a "reload from cache" using a cookie, setting up various response headers) and here are the only two solutions that worked from me:

1- Easy way: create your iframe dynamically from javascript

For example:

const iframe = document.createElement('iframe')
iframe.id = ...
...
iframe.src = myIFrameUrl 
document.body.appendChild(iframe)

2- Convoluted way

Server-side, as explained here, disable content caching for the content you serve for the iframe OR for the parent page (either will do).

AND

Set the iframe url from javascript with an additional changing search param, like this:

const url = myIFrameUrl + '?timestamp=' + new Date().getTime()
document.getElementById('my-iframe-id').src = url

(simplified version, beware of other search params)

This is a bug in Firefox:

https://bugzilla.mozilla.org/show_bug.cgi?id=356558

Try this workaround:

<iframe src="webpage2.html?var=xxx" id="theframe"></iframe>
    
<script>
    var _theframe = document.getElementById("theframe");
    _theframe.contentWindow.location.href = _theframe.src;
</script>