Argh, ShareThis!

Despite it's importance, this problem with ShareThis is almost totally undocumented: if you run your webserver locally and access it via "localhost"then the ShareThis widget won't work. You have to access it by an IP instead (127.0.0.1).

So if you get "SHARETHIS is null," "SHARETHIS is undefined," or "SHARETHIS is not defined," instead of spending an hour and a half pulling your hair out, just breathe deep and remember, there are still people out there who put all their code in a monotholic try/catch and fail silently.