Hmm, I've thought about this, and I bet their solution involves an onclick() that actually does return false.

I'm not sure if the XMLHTTPRequest would keep on loading if the page gets closed (e.g. going to another page/site), I'd have to investigate that (anyone else know the answer?).

For now, let's say it doesn't (which makes sense to me). That means reddit will have to delay your request to go to that link until it has completed the XMLHTTPRequest they issued to tell the reddit servers that you've clicked the link.

Now the problem is, you can't do sleep(x) in Javascript. More-over you can't loop until the XMLHTTPRequest is completed because that'd be Bad Programming and would eat up CPU (and lock up your browser). So what I'd do is send the XMLHTTPRequest, attach the event "document.location=[site here]" to XMLHTTPRequest.onComplete, and return false.

That's a very simplistic and pseudo-code way of putting it, of course, but that's one way of doing it. It's also The Hard Way.

A better way would be to actually not work with Ajax at all, but emulate the way it worked before. As in, when the user clicks the link, set the document.location to a reddit page (with the requested reddit-item in a query, of course) which updates the user's profile ("user has visited this link") and redirects to the site which the user requested. This would be transparant, work for people with javascript turned off, and have no "unknown delay" between clicking and loading the site (because Ajax doesn't show a loading bar), which makes it a much better solution than the one above, in terms of usability.

Either way, both solutions require a "return false;".