Why an AJAX history manager?

Now, I've written just a simple AJAX history script that adds back/forward buttons and changes the hash bang. But I was reading up on other history scripts that store previous AJAX requests for later, so a script doesn't have to reconstruct the requests again. These, I suppose, make the distincti开发者_开发问答on between a history script and a history manager.

My question, however, is why you'd need a manager? For example, say you did something like this: addHistory('my/funny/url', 'ajax/url');

The manager is going to store ajax/url in reference to my/funny/url. But if a user deletes the cache and goes back to my/funny/url, you're still going to have to reconstruct the url from scratch anyways. So, I don't really see the point.

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My guess would be that it is an attempt to remember the changes of server side session state at the client. And maybe they even do not consider the scenario of clearing the cache.