This is an old question, but I ran into the same problem, maybe it can help someone.
offline.js creating these dom elements on page load inside the body HTML
<div class="offline-ui offline-ui-up">
<div class="offline-ui-content"></div>
<a href="" class="offline-ui-retry"></a>
</div>
The reason why offline.js not working after page change is that on-page change the body HTML replaced with the new content returned by the server and the code above removed.
This is how Turbolinks works, so page load will be not triggered and the offline.js dom elements will be not created.
One solution will be to warp the offline.js inside a function and call it on every page change, but it will cause eventually memory leak (as "offline" and "online" event listener will be added to 'window' on each change)
Other solution will be to save the 'offline-ui' HTML before the new page loaded and bring it back after load:
# will fire before page change and save offline.js UI
document.addEventListener("turbolinks:before-render", function() {
if (!document.offlineHtml) {
document.offlineHtml = $('.offline-ui');
}
});
# will fire afterload and will check if there is a UI to append to the body
document.addEventListener("turbolinks:load", function() {
if (document.offlineHtml) {
$(document.body).append(document.offlineHtml);
}
});
At the moment this is the best way that I could find to fix that.