Media galleries (carousels) were client side things at least since the original xhr implementation in IE5. Maybe well before that if changing the src of a img let the browser load the new one from the server. I can't remember.
But sites were small and even loading all the page again was not that bad.
By the way, Rails Tutbolinks [1] are a way to get the same result with the server rendering only the html body and the js code in the browser swapping it with the current one.
IIRC, Turbolinks work by loading pages in the background in response to a mouseover event - by the time a click has registered, the remote content has already been downloaded and just needs to be injected into the page. The speed-up comes from anticipating clicks, not from JavaScript tomfoolery.
I checked the README and it never mentions mouseover
> Turbolinks intercepts all clicks on <a href> links to the same domain. When you click an eligible link, Turbolinks prevents the browser from following it. Instead, Turbolinks changes the browser’s URL using the History API, requests the new page using XMLHttpRequest, and then renders the HTML response.
I think you're thinking of https://instant.page/ , which is pretty much as simple as "when link is moused over, tell browser to load the page in the background".
But sites were small and even loading all the page again was not that bad.
By the way, Rails Tutbolinks [1] are a way to get the same result with the server rendering only the html body and the js code in the browser swapping it with the current one.
[1] https://github.com/turbolinks/turbolinks